1 Implementation Note 2 3 KAME Project 4 https://www.kame.net/ 5 $KAME: IMPLEMENTATION,v 1.216 2001/05/25 07:43:01 jinmei Exp $ 6 7NOTE: The document tries to describe behaviors/implementation choices 8of the latest KAME/*BSD stack. The description here may not be 9applicable to KAME-integrated *BSD releases, as we have certain amount 10of changes between them. Still, some of the content can be useful for 11KAME-integrated *BSD releases. 12 13Table of Contents 14 15 1. IPv6 16 1.1 Conformance 17 1.2 Neighbor Discovery 18 1.3 Scope Zone Index 19 1.3.1 Kernel internal 20 1.3.2 Interaction with API 21 1.3.3 Interaction with users (command line) 22 1.4 Plug and Play 23 1.4.1 Assignment of link-local, and special addresses 24 1.4.2 Stateless address autoconfiguration on hosts 25 1.4.3 DHCPv6 26 1.5 Generic tunnel interface 27 1.6 Address Selection 28 1.6.1 Source Address Selection 29 1.6.2 Destination Address Ordering 30 1.7 Jumbo Payload 31 1.8 Loop prevention in header processing 32 1.9 ICMPv6 33 1.10 Applications 34 1.11 Kernel Internals 35 1.12 IPv4 mapped address and IPv6 wildcard socket 36 1.12.1 KAME/BSDI3 and KAME/FreeBSD228 37 1.12.2 KAME/FreeBSD[34]x 38 1.12.2.1 KAME/FreeBSD[34]x, listening side 39 1.12.2.2 KAME/FreeBSD[34]x, initiating side 40 1.12.3 KAME/NetBSD 41 1.12.3.1 KAME/NetBSD, listening side 42 1.12.3.2 KAME/NetBSD, initiating side 43 1.12.4 KAME/BSDI4 44 1.12.4.1 KAME/BSDI4, listening side 45 1.12.4.2 KAME/BSDI4, initiating side 46 1.12.5 KAME/OpenBSD 47 1.12.5.1 KAME/OpenBSD, listening side 48 1.12.5.2 KAME/OpenBSD, initiating side 49 1.12.6 More issues 50 1.12.7 Interaction with SIIT translator 51 1.13 sockaddr_storage 52 1.14 Invalid addresses on the wire 53 1.15 Node's required addresses 54 1.15.1 Host case 55 1.15.2 Router case 56 1.16 Advanced API 57 1.17 DNS resolver 58 2. Network Drivers 59 2.1 FreeBSD 2.2.x-RELEASE 60 2.2 BSD/OS 3.x 61 2.3 NetBSD 62 2.4 FreeBSD 3.x-RELEASE 63 2.5 FreeBSD 4.x-RELEASE 64 2.6 OpenBSD 2.x 65 2.7 BSD/OS 4.x 66 3. Translator 67 3.1 FAITH TCP relay translator 68 3.2 IPv6-to-IPv4 header translator 69 4. IPsec 70 4.1 Policy Management 71 4.2 Key Management 72 4.3 AH and ESP handling 73 4.4 IPComp handling 74 4.5 Conformance to RFCs and IDs 75 4.6 ECN consideration on IPsec tunnels 76 4.7 Interoperability 77 4.8 Operations with IPsec tunnel mode 78 4.8.1 RFC2401 IPsec tunnel mode approach 79 4.8.2 draft-touch-ipsec-vpn approach 80 5. ALTQ 81 6. Mobile IPv6 82 6.1 KAME node as correspondent node 83 6.2 KAME node as home agent/mobile node 84 6.3 Old Mobile IPv6 code 85 7. Coding style 86 8. Policy on technology with intellectual property right restriction 87 881. IPv6 89 901.1 Conformance 91 92The KAME kit conforms, or tries to conform, to the latest set of IPv6 93specifications. For future reference we list some of the relevant documents 94below (NOTE: this is not a complete list - this is too hard to maintain...). 95For details please refer to specific chapter in the document, RFCs, manpages 96come with KAME, or comments in the source code. 97 98Conformance tests have been performed on past and latest KAME STABLE kit, 99at TAHI project. Results can be viewed at http://www.tahi.org/report/KAME/. 100We also attended Univ. of New Hampshire IOL tests (http://www.iol.unh.edu/) 101in the past, with our past snapshots. 102 103RFC1639: FTP Operation Over Big Address Records (FOOBAR) 104 * RFC2428 is preferred over RFC1639. ftp clients will first try RFC2428, 105 then RFC1639 if failed. 106RFC1886: DNS Extensions to support IPv6 107RFC1933: (see RFC2893) 108RFC1981: Path MTU Discovery for IPv6 109RFC2080: RIPng for IPv6 110 * KAME-supplied route6d, bgpd and hroute6d support this. 111RFC2283: Multiprotocol Extensions for BGP-4 112 * so-called "BGP4+". 113 * KAME-supplied bgpd supports this. 114RFC2292: Advanced Sockets API for IPv6 115 * see RFC3542 116RFC2362: Protocol Independent Multicast-Sparse Mode (PIM-SM) 117 * RFC2362 defines the packet formats and the protcol of PIM-SM. 118RFC2373: IPv6 Addressing Architecture 119 * KAME supports node required addresses, and conforms to the scope 120 requirement. 121RFC2374: An IPv6 Aggregatable Global Unicast Address Format 122 * KAME supports 64-bit length of Interface ID. 123RFC2375: IPv6 Multicast Address Assignments 124 * Userland applications use the well-known addresses assigned in the RFC. 125RFC2428: FTP Extensions for IPv6 and NATs 126 * RFC2428 is preferred over RFC1639. ftp clients will first try RFC2428, 127 then RFC1639 if failed. 128RFC2460: IPv6 specification 129RFC2461: Neighbor discovery for IPv6 130 * See 1.2 in this document for details. 131RFC2462: IPv6 Stateless Address Autoconfiguration 132 * See 1.4 in this document for details. 133RFC2463: ICMPv6 for IPv6 specification 134 * See 1.9 in this document for details. 135RFC2464: Transmission of IPv6 Packets over Ethernet Networks 136RFC2465: MIB for IPv6: Textual Conventions and General Group 137 * Necessary statistics are gathered by the kernel. Actual IPv6 MIB 138 support is provided as patchkit for ucd-snmp. 139RFC2466: MIB for IPv6: ICMPv6 group 140 * Necessary statistics are gathered by the kernel. Actual IPv6 MIB 141 support is provided as patchkit for ucd-snmp. 142RFC2467: Transmission of IPv6 Packets over FDDI Networks 143RFC2472: IPv6 over PPP 144RFC2492: IPv6 over ATM Networks 145 * only PVC is supported. 146RFC2497: Transmission of IPv6 packet over ARCnet Networks 147RFC2545: Use of BGP-4 Multiprotocol Extensions for IPv6 Inter-Domain Routing 148RFC2553: (see RFC3493) 149RFC2671: Extension Mechanisms for DNS (EDNS0) 150 * see USAGE for how to use it. 151 * not supported on kame/freebsd4 and kame/bsdi4. 152RFC2673: Binary Labels in the Domain Name System 153 * KAME/bsdi4 supports A6, DNAME and binary label to some extent. 154 * KAME apps/bind8 repository has resolver library with partial A6, DNAME 155 and binary label support. 156RFC2675: IPv6 Jumbograms 157 * See 1.7 in this document for details. 158RFC2710: Multicast Listener Discovery for IPv6 159RFC2711: IPv6 router alert option 160RFC2732: Format for Literal IPv6 Addresses in URL's 161 * The spec is implemented in programs that handle URLs 162 (like freebsd ftpio(3) and fetch(1), or netbsd ftp(1)) 163RFC2874: DNS Extensions to Support IPv6 Address Aggregation and Renumbering 164 * KAME/bsdi4 supports A6, DNAME and binary label to some extent. 165 * KAME apps/bind8 repository has resolver library with partial A6, DNAME 166 and binary label support. 167RFC2893: Transition Mechanisms for IPv6 Hosts and Routers 168 * IPv4 compatible address is not supported. 169 * automatic tunneling (4.3) is not supported. 170 * "gif" interface implements IPv[46]-over-IPv[46] tunnel in a generic way, 171 and it covers "configured tunnel" described in the spec. 172 See 1.5 in this document for details. 173RFC2894: Router renumbering for IPv6 174RFC3041: Privacy Extensions for Stateless Address Autoconfiguration in IPv6 175RFC3056: Connection of IPv6 Domains via IPv4 Clouds 176 * So-called "6to4". 177 * "stf" interface implements it. Be sure to read 178 draft-itojun-ipv6-transition-abuse-01.txt 179 below before configuring it, there can be security issues. 180RFC3142: An IPv6-to-IPv4 transport relay translator 181 * FAITH tcp relay translator (faithd) implements this. See 3.1 for more 182 details. 183RFC3152: Delegation of IP6.ARPA 184 * libinet6 resolvers contained in the KAME snaps support to use 185 the ip6.arpa domain (with the nibble format) for IPv6 reverse 186 lookups. 187RFC3484: Default Address Selection for IPv6 188 * the selection algorithm for both source and destination addresses 189 is implemented based on the RFC, though some rules are still omitted. 190RFC3493: Basic Socket Interface Extensions for IPv6 191 * IPv4 mapped address (3.7) and special behavior of IPv6 wildcard bind 192 socket (3.8) are, 193 - supported and turned on by default on KAME/FreeBSD[34] 194 and KAME/BSDI4, 195 - supported but turned off by default on KAME/NetBSD and KAME/FreeBSD5, 196 - not supported on KAME/FreeBSD228, KAME/OpenBSD and KAME/BSDI3. 197 see 1.12 in this document for details. 198 * The AI_ALL and AI_V4MAPPED flags are not supported. 199RFC3542: Advanced Sockets API for IPv6 (revised) 200 * For supported library functions/kernel APIs, see sys/netinet6/ADVAPI. 201 * Some of the updates in the draft are not implemented yet. See 202 TODO.2292bis for more details. 203RFC4007: IPv6 Scoped Address Architecture 204 * some part of the documentation (especially about the routing 205 model) is not supported yet. 206 * zone indices that contain scope types have not been supported yet. 207 208draft-ietf-ipngwg-icmp-name-lookups-09: IPv6 Name Lookups Through ICMP 209draft-ietf-ipv6-router-selection-07.txt: 210 Default Router Preferences and More-Specific Routes 211 * router-side: both router preference and specific routes are supported. 212 * host-side: only router preference is supported. 213draft-ietf-pim-sm-v2-new-02.txt 214 A revised version of RFC2362, which includes the IPv6 specific 215 packet format and protocol descriptions. 216draft-ietf-dnsext-mdns-00.txt: Multicast DNS 217 * kame/mdnsd has test implementation, which will not be built in 218 default compilation. The draft will experience a major change in the 219 near future, so don't rely upon it. 220draft-ietf-ipngwg-icmp-v3-02.txt: ICMPv6 for IPv6 specification (revised) 221 * See 1.9 in this document for details. 222draft-itojun-ipv6-tcp-to-anycast-01.txt: 223 Disconnecting TCP connection toward IPv6 anycast address 224draft-ietf-ipv6-rfc2462bis-06.txt: IPv6 Stateless Address 225 Autoconfiguration (revised) 226draft-itojun-ipv6-transition-abuse-01.txt: 227 Possible abuse against IPv6 transition technologies (expired) 228 * KAME does not implement RFC1933/2893 automatic tunnel. 229 * "stf" interface implements some address filters. Refer to stf(4) 230 for details. Since there's no way to make 6to4 interface 100% secure, 231 we do not include "stf" interface into GENERIC.v6 compilation. 232 * kame/openbsd completely disables IPv4 mapped address support. 233 * kame/netbsd makes IPv4 mapped address support off by default. 234 * See section 1.12.6 and 1.14 for more details. 235draft-itojun-ipv6-flowlabel-api-01.txt: Socket API for IPv6 flow label field 236 * no consideration is made against the use of routing headers and such. 237 2381.2 Neighbor Discovery 239 240Our implementation of Neighbor Discovery is fairly stable. Currently 241Address Resolution, Duplicated Address Detection, and Neighbor 242Unreachability Detection are supported. In the near future we will be 243adding an Unsolicited Neighbor Advertisement transmission command as 244an administration tool. 245 246Duplicated Address Detection (DAD) will be performed when an IPv6 address 247is assigned to a network interface, or the network interface is enabled 248(ifconfig up). It is documented in RFC2462 5.4. 249If DAD fails, the address will be marked "duplicated" and message will be 250generated to syslog (and usually to console). The "duplicated" mark 251can be checked with ifconfig. It is administrators' responsibility to check 252for and recover from DAD failures. We may try to improve failure recovery 253in future KAME code. 254 255A successor version of RFC2462 (called rfc2462bis) clarifies the 256behavior when DAD fails (i.e., duplicate is detected): if the 257duplicate address is a link-local address formed from an interface 258identifier based on the hardware address which is supposed to be 259uniquely assigned (e.g., EUI-64 for an Ethernet interface), IPv6 260operation on the interface should be disabled. The KAME 261implementation supports this as follows: if this type of duplicate is 262detected, the kernel marks "disabled" in the ND specific data 263structure for the interface. Every IPv6 I/O operation in the kernel 264checks this mark, and the kernel will drop packets received on or 265being sent to the "disabled" interface. Whether the IPv6 operation is 266disabled or not can be confirmed by the ndp(8) command. See the man 267page for more details. 268 269DAD procedure may not be effective on certain network interfaces/drivers. 270If a network driver needs long initialization time (with wireless network 271interfaces this situation is popular), and the driver mistakingly raises 272IFF_RUNNING before the driver becomes ready, DAD code will try to transmit 273DAD probes to not-really-ready network driver and the packet will not go out 274from the interface. In such cases, network drivers should be corrected. 275 276Some of network drivers loop multicast packets back to themselves, 277even if instructed not to do so (especially in promiscuous mode). In 278such cases DAD may fail, because the DAD engine sees inbound NS packet 279(actually from the node itself) and considers it as a sign of 280duplicate. In this case, drivers should be corrected to honor 281IFF_SIMPLEX behavior. For example, you may need to check source MAC 282address on an inbound packet, and reject it if it is from the node 283itself. 284 285Neighbor Discovery specification (RFC2461) does not talk about neighbor 286cache handling in the following cases: 287(1) when there was no neighbor cache entry, node received unsolicited 288 RS/NS/NA/redirect packet without link-layer address 289(2) neighbor cache handling on medium without link-layer address 290 (we need a neighbor cache entry for IsRouter bit) 291For (1), we implemented workaround based on discussions on IETF ipngwg mailing 292list. For more details, see the comments in the source code and email 293thread started from (IPng 7155), dated Feb 6 1999. 294 295IPv6 on-link determination rule (RFC2461) is quite different from 296assumptions in BSD IPv4 network code. To implement the behavior in 297RFC2461 section 6.3.6 (3), the kernel needs to know the default 298outgoing interface. To configure the default outgoing interface, use 299commands like "ndp -I de0" as root. Then the kernel will have a 300"default" route to the interface with the cloning "C" bit being on. 301This default route will cause to make a neighbor cache entry for every 302destination that does not match an explicit route entry. 303 304Note that we intentionally disable configuring the default interface 305by default. This is because we found it sometimes caused inconvenient 306situation while it was rarely useful in practical usage. For example, 307consider a destination that has both IPv4 and IPv6 addresses but is 308only reachable via IPv4. Since our getaddrinfo(3) prefers IPv6 by 309default, an (TCP) application using the library with PF_UNSPEC first 310tries to connect to the IPv6 address. If we turn on RFC 2461 6.3.6 311(3), we have to wait for quite a long period before the first attempt 312to make a connection fails. If we turn it off, the first attempt will 313immediately fail with EHOSTUNREACH, and then the application can try 314the next, reachable address. 315 316The notion of the default interface is also disabled when the node is 317acting as a router. The reason is that routers tend to control all 318routes stored in the kernel and the default route automatically 319installed would rather confuse the routers. Note that the spec misuse 320the word "host" and "node" in several places in Section 5.2 of RFC 3212461. We basically read the word "node" in this section as "host," 322and thus believe the implementation policy does not break the 323specification. 324 325To avoid possible DoS attacks and infinite loops, KAME stack will accept 326only 10 options on ND packet. Therefore, if you have 20 prefix options 327attached to RA, only the first 10 prefixes will be recognized. 328If this troubles you, please contact the KAME team and/or modify 329nd6_maxndopt in sys/netinet6/nd6.c. If there are high demands we may 330provide a sysctl knob for the variable. 331 332Proxy Neighbor Advertisement support is implemented in the kernel. 333For instance, you can configure it by using the following command: 334 # ndp -s fe80::1234%ne0 0:1:2:3:4:5 proxy 335where ne0 is the interface which attaches to the same link as the 336proxy target. 337There are certain limitations, though: 338- It does not send unsolicited multicast NA on configuration. This is MAY 339 behavior in RFC2461. 340- It does not add random delay before transmission of solicited NA. This is 341 SHOULD behavior in RFC2461. 342- We cannot configure proxy NDP for off-link address. The target address for 343 proxying must be link-local address, or must be in prefixes configured to 344 node which does proxy NDP. 345- RFC2461 is unclear about if it is legal for a host to perform proxy ND. 346 We do not prohibit hosts from doing proxy ND, but there will be very limited 347 use in it. 348 349Starting mid March 2000, we support Neighbor Unreachability Detection 350(NUD) on p2p interfaces, including tunnel interfaces (gif). NUD is 351turned on by default. Before March 2000 the KAME stack did not 352perform NUD on p2p interfaces. If the change raises any 353interoperability issues, you can turn off/on NUD by per-interface 354basis. Use "ndp -i interface -nud" to turn it off. Consult ndp(8) 355for details. 356 357RFC2461 specifies upper-layer reachability confirmation hint. Whenever 358upper-layer reachability confirmation hint comes, ND process can use it 359to optimize neighbor discovery process - ND process can omit real ND exchange 360and keep the neighbor cache state in REACHABLE. 361We currently have two sources for hints: (1) setsockopt(IPV6_REACHCONF) 362defined by the RFC3542 API, and (2) hints from tcp(6)_input. 363 364It is questionable if they are really trustworthy. For example, a 365rogue userland program can use IPV6_REACHCONF to confuse the ND 366process. Neighbor cache is a system-wide information pool, and it is 367bad to allow a single process to affect others. Also, tcp(6)_input 368can be hosed by hijack attempts. It is wrong to allow hijack attempts 369to affect the ND process. 370 371Starting June 2000, the ND code has a protection mechanism against 372incorrect upper-layer reachability confirmation. The ND code counts 373subsequent upper-layer hints. If the number of hints reaches the 374maximum, the ND code will ignore further upper-layer hints and run 375real ND process to confirm reachability to the peer. sysctl 376net.inet6.icmp6.nd6_maxnudhint defines the maximum # of subsequent 377upper-layer hints to be accepted. 378(from April 2000 to June 2000, we rejected setsockopt(IPV6_REACHCONF) from 379non-root process - after a local discussion, it looks that hints are not 380that trustworthy even if they are from privileged processes) 381 382If inbound ND packets carry invalid values, the KAME kernel will 383drop these packet and increment statistics variable. See 384"netstat -sn", icmp6 section. For detailed debugging session, you can 385turn on syslog output from the kernel on errors, by turning on sysctl MIB 386net.inet6.icmp6.nd6_debug. nd6_debug can be turned on at bootstrap 387time, by defining ND6_DEBUG kernel compilation option (so you can 388debug behavior during bootstrap). nd6_debug configuration should 389only be used for test/debug purposes - for a production environment, 390nd6_debug must be set to 0. If you leave it to 1, malicious parties 391can inject broken packet and fill up /var/log partition. 392 3931.3 Scope Zone Index 394 395IPv6 uses scoped addresses. It is therefore very important to 396specify the scope zone index (link index for a link-local address, or 397site index for a site-local address) with an IPv6 address. Without a 398zone index, a scoped IPv6 address is ambiguous to the kernel, and 399the kernel would not be able to determine the outbound zone for a 400packet to the scoped address. KAME code tries to address the issue in 401several ways. 402 403The entire architecture of scoped addresses is documented in RFC4007. 404One non-trivial point of the architecture is that the link scope is 405(theoretically) larger than the interface scope. That is, two 406different interfaces can belong to a same single link. However, in a 407normal operation, we can assume that there is 1-to-1 relationship 408between links and interfaces. In other words, we can usually put 409links and interfaces in the same scope type. The current KAME 410implementation assumes the 1-to-1 relationship. In particular, we use 411interface names such as "ne1" as unique link identifiers. This would 412be much more human-readable and intuitive than numeric identifiers, 413but please keep your mind on the theoretical difference between links 414and interfaces. 415 416Site-local addresses are very vaguely defined in the specs, and both 417the specification and the KAME code need tons of improvements to 418enable its actual use. For example, it is still very unclear how we 419define a site, or how we resolve host names in a site. There is work 420underway to define behavior of routers at site border, but, we have 421almost no code for site boundary node support (neither forwarding nor 422routing) and we bet almost noone has. We recommend, at this moment, 423you to use global addresses for experiments - there are way too many 424pitfalls if you use site-local addresses. 425 4261.3.1 Kernel internal 427 428In the kernel, the link index for a link-local scope address is 429embedded into the 2nd 16bit-word (the 3rd and 4th bytes) in the IPv6 430address. 431For example, you may see something like: 432 fe80:1::200:f8ff:fe01:6317 433in the routing table and the interface address structure (struct 434in6_ifaddr). The address above is a link-local unicast address which 435belongs to a network link whose link identifier is 1 (note that it 436eqauls to the interface index by the assumption of our 437implementation). The embedded index enables us to identify IPv6 438link-local addresses over multiple links effectively and with only a 439little code change. 440 441The use of the internal format must be limited inside the kernel. In 442particular, addresses sent by an application should not contain the 443embedded index (except via some very special APIs such as routing 444sockets). Instead, the index should be specified in the sin6_scope_id 445field of a sockaddr_in6 structure. Obviously, packets sent to or 446received from must not contain the embedded index either, since the 447index is meaningful only within the sending/receiving node. 448 449In order to deal with the differences, several kernel routines are 450provided. These are available by including <netinet6/scope_var.h>. 451Typically, the following functions will be most generally used: 452 453- int sa6_embedscope(struct sockaddr_in6 *sa6, int defaultok); 454 Embed sa6->sin6_scope_id into sa6->sin6_addr. If sin6_scope_id is 455 0, defaultok is non-0, and the default zone ID (see RFC4007) is 456 configured, the default ID will be used instead of the value of the 457 sin6_scope_id field. On success, sa6->sin6_scope_id will be reset 458 to 0. 459 460 This function returns 0 on success, or a non-0 error code otherwise. 461 462- int sa6_recoverscope(struct sockaddr_in6 *sa6); 463 Extract embedded zone ID in sa6->sin6_addr and set 464 sa6->sin6_scope_id to that ID. The embedded ID will be cleared with 465 0. 466 467 This function returns 0 on success, or a non-0 error code otherwise. 468 469- int in6_clearscope(struct in6_addr *in6); 470 Reset the embedded zone ID in 'in6' to 0. This function never fails, and 471 returns 0 if the original address is intact or non 0 if the address is 472 modified. The return value doesn't matter in most cases; currently, the 473 only point where we care about the return value is ip6_input() for checking 474 whether the source or destination addresses of the incoming packet is in 475 the embedded form. 476 477- int in6_setscope(struct in6_addr *in6, struct ifnet *ifp, 478 u_int32_t *zoneidp); 479 Embed zone ID determined by the address scope type for 'in6' and the 480 interface 'ifp' into 'in6'. If zoneidp is non NULL, *zoneidp will 481 also have the zone ID. 482 483 This function returns 0 on success, or a non-0 error code otherwise. 484 485The typical usage of these functions is as follows: 486 487sa6_embedscope() will be used at the socket or transport layer to 488convert a sockaddr_in6 structure passed by an application into the 489kernel-internal form. In this usage, the second argument is often the 490'ip6_use_defzone' global variable. 491 492sa6_recoverscope() will also be used at the socket or transport layer 493to convert an in6_addr structure with the embedded zone ID into a 494sockaddr_in6 structure with the corresponding ID in the sin6_scope_id 495field (and without the embedded ID in sin6_addr). 496 497in6_clearscope() will be used just before sending a packet to the wire 498to remove the embedded ID. In general, this must be done at the last 499stage of an output path, since otherwise the address would lose the ID 500and could be ambiguous with regard to scope. 501 502in6_setscope() will be used when the kernel receives a packet from the 503wire to construct the kernel internal form for each address field in 504the packet (typical examples are the source and destination addresses 505of the packet). In the typical usage, the third argument 'zoneidp' 506will be NULL. A non-NULL value will be used when the validity of the 507zone ID must be checked, e.g., when forwarding a packet to another 508link (see ip6_forward() for this usage). 509 510An application, when sending a packet, is basically assumed to specify 511the appropriate scope zone of the destination address by the 512sin6_scope_id field (this might be done transparently from the 513application with getaddrinfo() and the extended textual format - see 514below), or at least the default scope zone(s) must be configured as a 515last resort. In some cases, however, an application could specify an 516ambiguous address with regard to scope, expecting it is disambiguated 517in the kernel by some other means. A typical usage is to specify the 518outgoing interface through another API, which can disambiguate the 519unspecified scope zone. Such a usage is not recommended, but the 520kernel implements some trick to deal with even this case. 521 522A rough sketch of the trick can be summarized as the following 523sequence. 524 525 sa6_embedscope(dst, ip6_use_defzone); 526 in6_selectsrc(dst, ..., &ifp, ...); 527 in6_setscope(&dst->sin6_addr, ifp, NULL); 528 529sa6_embedscope() first tries to convert sin6_scope_id (or the default 530zone ID) into the kernel-internal form. This can fail with an 531ambiguous destination, but it still tries to get the outgoing 532interface (ifp) in the attempt of determining the source address of 533the outgoing packet using in6_selectsrc(). If the interface is 534detected, and the scope zone was originally ambiguous, in6_setscope() 535can finally determine the appropriate ID with the address itself and 536the interface, and construct the kernel-internal form. See, for 537example, comments in udp6_output() for more concrete example. 538 539In any case, kernel routines except ones in netinet6/scope6.c MUST NOT 540directly refer to the embedded form. They MUST use the above 541interface functions. In particular, kernel routines MUST NOT have the 542following code fragment: 543 544 /* This is a bad practice. Don't do this */ 545 if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)) 546 sin6->sin6_addr.s6_addr16[1] = htons(ifp->if_index); 547 548This is bad for several reasons. First, address ambiguity is not 549specific to link-local addresses (any non-global multicast addresses 550are inherently ambiguous, and this is particularly true for 551interface-local addresses). Secondly, this is vulnerable to future 552changes of the embedded form (the embedded position may change, or the 553zone ID may not actually be the interface index). Only scope6.c 554routines should know the details. 555 556The above code fragment should thus actually be as follows: 557 558 /* This is correct. */ 559 in6_setscope(&sin6->sin6_addr, ifp, NULL); 560 (and catch errors if possible and necessary) 561 5621.3.2 Interaction with API 563 564There are several candidates of API to deal with scoped addresses 565without ambiguity. 566 567The IPV6_PKTINFO ancillary data type or socket option defined in the 568advanced API (RFC2292 or RFC3542) can specify 569the outgoing interface of a packet. Similarly, the IPV6_PKTINFO or 570IPV6_RECVPKTINFO socket options tell kernel to pass the incoming 571interface to user applications. 572 573These options are enough to disambiguate scoped addresses of an 574incoming packet, because we can uniquely identify the corresponding 575zone of the scoped address(es) by the incoming interface. However, 576they are too strong for outgoing packets. For example, consider a 577multi-sited node and suppose that more than one interface of the node 578belongs to a same site. When we want to send a packet to the site, 579we can only specify one of the interfaces for the outgoing packet with 580these options; we cannot just say "send the packet to (one of the 581interfaces of) the site." 582 583Another kind of candidates is to use the sin6_scope_id member in the 584sockaddr_in6 structure, defined in RFC2553. The KAME kernel 585interprets the sin6_scope_id field properly in order to disambiguate scoped 586addresses. For example, if an application passes a sockaddr_in6 587structure that has a non-zero sin6_scope_id value to the sendto(2) 588system call, the kernel should send the packet to the appropriate zone 589according to the sin6_scope_id field. Similarly, when the source or 590the destination address of an incoming packet is a scoped one, the 591kernel should detect the correct zone identifier based on the address 592and the receiving interface, fill the identifier in the sin6_scope_id 593field of a sockaddr_in6 structure, and then pass the packet to an 594application via the recvfrom(2) system call, etc. 595 596However, the semantics of the sin6_scope_id is still vague and on the 597way to standardization. Additionally, not so many operating systems 598support the behavior above at this moment. 599 600In summary, 601- If your target system is limited to KAME based ones (i.e. BSD 602 variants and KAME snaps), use the sin6_scope_id field assuming the 603 kernel behavior described above. 604- Otherwise, (i.e. if your program should be portable on other systems 605 than BSDs) 606 + Use the advanced API to disambiguate scoped addresses of incoming 607 packets. 608 + To disambiguate scoped addresses of outgoing packets, 609 * if it is okay to just specify the outgoing interface, use the 610 advanced API. This would be the case, for example, when you 611 should only consider link-local addresses and your system 612 assumes 1-to-1 relationship between links and interfaces. 613 * otherwise, sorry but you lose. Please rush the IETF IPv6 614 community into standardizing the semantics of the sin6_scope_id 615 field. 616 617Routing daemons and configuration programs, like route6d and ifconfig, 618will need to manipulate the "embedded" zone index. These programs use 619routing sockets and ioctls (like SIOCGIFADDR_IN6) and the kernel API 620will return IPv6 addresses with the 2nd 16bit-word filled in. The 621APIs are for manipulating kernel internal structure. Programs that 622use these APIs have to be prepared about differences in kernels 623anyway. 624 625getaddrinfo(3) and getnameinfo(3) support an extended numeric IPv6 626syntax, as documented in RFC4007. You can specify the outgoing link, 627by using the name of the outgoing interface as the link, like 628"fe80::1%ne0" (again, note that we assume there is 1-to-1 relationship 629between links and interfaces.) This way you will be able to specify a 630link-local scoped address without much trouble. 631 632Other APIs like inet_pton(3) and inet_ntop(3) are inherently 633unfriendly with scoped addresses, since they are unable to annotate 634addresses with zone identifier. 635 6361.3.3 Interaction with users (command line) 637 638Most of user applications now support the extended numeric IPv6 639syntax. In this case, you can specify outgoing link, by using the name 640of the outgoing interface like "fe80::1%ne0" (sorry for the duplicated 641notice, but please recall again that we assume 1-to-1 relationship 642between links and interfaces). This is even the case for some 643management tools such as route(8) or ndp(8). For example, to install 644the IPv6 default route by hand, you can type like 645 # route add -inet6 default fe80::9876:5432:1234:abcd%ne0 646(Although we suggest you to run dynamic routing instead of static 647routes, in order to avoid configuration mistakes.) 648 649Some applications have command line options for specifying an 650appropriate zone of a scoped address (like "ping6 -I ne0 ff02::1" to 651specify the outgoing interface). However, you can't always expect such 652options. Additionally, specifying the outgoing "interface" is in 653theory an overspecification as a way to specify the outgoing "link" 654(see above). Thus, we recommend you to use the extended format 655described above. This should apply to the case where the outgoing 656interface is specified. 657 658In any case, when you specify a scoped address to the command line, 659NEVER write the embedded form (such as ff02:1::1 or fe80:2::fedc), 660which should only be used inside the kernel (see Section 1.3.1), and 661is not supposed to work. 662 6631.4 Plug and Play 664 665The KAME kit implements most of the IPv6 stateless address 666autoconfiguration in the kernel. 667Neighbor Discovery functions are implemented in the kernel as a whole. 668Router Advertisement (RA) input for hosts is implemented in the 669kernel. Router Solicitation (RS) output for endhosts, RS input 670for routers, and RA output for routers are implemented in the 671userland. 672 6731.4.1 Assignment of link-local, and special addresses 674 675IPv6 link-local address is generated from IEEE802 address (ethernet MAC 676address). Each of interface is assigned an IPv6 link-local address 677automatically, when the interface becomes up (IFF_UP). Also, direct route 678for the link-local address is added to routing table. 679 680Here is an output of netstat command: 681 682Internet6: 683Destination Gateway Flags Netif Expire 684fe80::%ed0/64 link#1 UC ed0 685fe80::%ep0/64 link#2 UC ep0 686 687Interfaces that has no IEEE802 address (pseudo interfaces like tunnel 688interfaces, or ppp interfaces) will borrow IEEE802 address from other 689interfaces, such as ethernet interfaces, whenever possible. 690If there is no IEEE802 hardware attached, last-resort pseudorandom value, 691which is from MD5(hostname), will be used as source of link-local address. 692If it is not suitable for your usage, you will need to configure the 693link-local address manually. 694 695If an interface is not capable of handling IPv6 (such as lack of multicast 696support), link-local address will not be assigned to that interface. 697See section 2 for details. 698 699Each interface joins the solicited multicast address and the 700link-local all-nodes multicast addresses (e.g. fe80::1:ff01:6317 701and ff02::1, respectively, on the link the interface is attached). 702In addition to a link-local address, the loopback address (::1) will be 703assigned to the loopback interface. Also, ::1/128 and ff01::/32 are 704automatically added to routing table, and loopback interface joins 705node-local multicast group ff01::1. 706 7071.4.2 Stateless address autoconfiguration on hosts 708 709In IPv6 specification, nodes are separated into two categories: 710routers and hosts. Routers forward packets addressed to others, hosts does 711not forward the packets. net.inet6.ip6.forwarding defines whether this 712node is a router or a host (router if it is 1, host if it is 0). 713 714It is NOT recommended to change net.inet6.ip6.forwarding while the node 715is in operation. IPv6 specification defines behavior for "host" and "router" 716quite differently, and switching from one to another can cause serious 717troubles. It is recommended to configure the variable at bootstrap time only. 718 719The first step in stateless address configuration is Duplicated Address 720Detection (DAD). See 1.2 for more detail on DAD. 721 722When a host hears Router Advertisement from the router, a host may 723autoconfigure itself by stateless address autoconfiguration. This 724behavior can be controlled by the net.inet6.ip6.accept_rtadv sysctl 725variable and a per-interface flag managed in the kernel. The latter, 726which we call "if_accept_rtadv" here, can be changed by the ndp(8) 727command (see the manpage for more details). When the sysctl variable 728is set to 1, and the flag is set, the host autoconfigures itself. By 729autoconfiguration, network address prefixes for the receiving 730interface (usually global address prefix) are added. The default 731route is also configured. 732 733Routers periodically generate Router Advertisement packets. To 734request an adjacent router to generate RA packet, a host can transmit 735Router Solicitation. To generate an RS packet at any time, use the 736"rtsol" command. The "rtsold" daemon is also available. "rtsold" 737generates Router Solicitation whenever necessary, and it works greatly 738for nomadic usage (notebooks/laptops). If one wishes to ignore Router 739Advertisements, use sysctl to set net.inet6.ip6.accept_rtadv to 0. 740Additionally, ndp(8) command can be used to control the behavior 741per-interface basis. 742 743To generate Router Advertisement from a router, use the "rtadvd" daemon. 744 745Note that the IPv6 specification assumes the following items and that 746nonconforming cases are left unspecified: 747- Only hosts will listen to router advertisements 748- Hosts have a single network interface (except loopback) 749This is therefore unwise to enable net.inet6.ip6.accept_rtadv on routers, 750or multi-interface hosts. A misconfigured node can behave strange 751(KAME code allows nonconforming configuration, for those who would like 752to do some experiments). 753 754To summarize the sysctl knob: 755 accept_rtadv forwarding role of the node 756 --- --- --- 757 0 0 host (to be manually configured) 758 0 1 router 759 1 0 autoconfigured host 760 (spec assumes that hosts have a single 761 interface only, autoconfigred hosts 762 with multiple interfaces are 763 out-of-scope) 764 1 1 invalid, or experimental 765 (out-of-scope of spec) 766 767The if_accept_rtadv flag is referred only when accept_rtadv is 1 (the 768latter two cases). The flag does not have any effects when the sysctl 769variable is 0. 770 771See 1.2 in the document for relationship between DAD and autoconfiguration. 772 7731.4.3 DHCPv6 774 775We supply a tiny DHCPv6 server/client in kame/dhcp6. However, the 776implementation is premature (for example, this does NOT implement 777address lease/release), and it is not in default compilation tree on 778some platforms. If you want to do some experiment, compile it on your 779own. 780 781DHCPv6 and autoconfiguration also needs more work. "Managed" and "Other" 782bits in RA have no special effect to stateful autoconfiguration procedure 783in DHCPv6 client program ("Managed" bit actually prevents stateless 784autoconfiguration, but no special action will be taken for DHCPv6 client). 785 7861.5 Generic tunnel interface 787 788GIF (Generic InterFace) is a pseudo interface for configured tunnel. 789Details are described in gif(4) manpage. 790Currently 791 v6 in v6 792 v6 in v4 793 v4 in v6 794 v4 in v4 795are available. Use "gifconfig" to assign physical (outer) source 796and destination address to gif interfaces. 797Configuration that uses same address family for inner and outer IP 798header (v4 in v4, or v6 in v6) is dangerous. It is very easy to 799configure interfaces and routing tables to perform infinite level 800of tunneling. Please be warned. 801 802gif can be configured to be ECN-friendly. See 4.5 for ECN-friendliness 803of tunnels, and gif(4) manpage for how to configure. 804 805If you would like to configure an IPv4-in-IPv6 tunnel with gif interface, 806read gif(4) carefully. You may need to remove IPv6 link-local address 807automatically assigned to the gif interface. 808 8091.6 Address Selection 810 8111.6.1 Source Address Selection 812 813The KAME kernel chooses the source address for an outgoing packet 814sent from a user application as follows: 815 8161. if the source address is explicitly specified via an IPV6_PKTINFO 817 ancillary data item or the socket option of that name, just use it. 818 Note that this item/option overrides the bound address of the 819 corresponding (datagram) socket. 820 8212. if the corresponding socket is bound, use the bound address. 822 8233. otherwise, the kernel first tries to find the outgoing interface of 824 the packet. If it fails, the source address selection also fails. 825 If the kernel can find an interface, choose the most appropriate 826 address based on the algorithm described in RFC3484. 827 828 The policy table used in this algorithm is stored in the kernel. 829 To install or view the policy, use the ip6addrctl(8) command. The 830 kernel does not have pre-installed policy. It is expected that the 831 default policy described in the draft should be installed at the 832 bootstrap time using this command. 833 834 This draft allows an implementation to add implementation-specific 835 rules with higher precedence than the rule "Use longest matching 836 prefix." KAME's implementation has the following additional rules 837 (that apply in the appeared order): 838 839 - prefer addresses on alive interfaces, that is, interfaces with 840 the UP flag being on. This rule is particularly useful for 841 routers, since some routing daemons stop advertising prefixes 842 (addresses) on interfaces that have become down. 843 844 - prefer addresses on "preferred" interfaces. "Preferred" 845 interfaces can be specified by the ndp(8) command. By default, 846 no interface is preferred, that is, this rule does not apply. 847 Again, this rule is particularly useful for routers, since there 848 is a convention, among router administrators, of assigning 849 "stable" addresses on a particular interface (typically a 850 loopback interface). 851 852 In any case, addresses that break the scope zone of the 853 destination, or addresses whose zone do not contain the outgoing 854 interface are never chosen. 855 856When the procedure above fails, the kernel usually returns 857EADDRNOTAVAIL to the application. 858 859In some cases, the specification explicitly requires the 860implementation to choose a particular source address. The source 861address for a Neighbor Advertisement (NA) message is an example. 862Under the spec (RFC2461 7.2.2) NA's source should be the target 863address of the corresponding NS's target. In this case we follow the 864spec rather than the above rule. 865 866If you would like to prohibit the use of deprecated address for some 867reason, configure net.inet6.ip6.use_deprecated to 0. The issue 868related to deprecated address is described in RFC2462 5.5.4 (NOTE: 869there is some debate underway in IETF ipngwg on how to use 870"deprecated" address). 871 872As documented in the source address selection document, temporary 873addresses for privacy extension are less preferred to public addresses 874by default. However, for administrators who are particularly aware of 875the privacy, there is a system-wide sysctl(3) variable 876"net.inet6.ip6.prefer_tempaddr". When the variable is set to 877non-zero, the kernel will rather prefer temporary addresses. The 878default value of this variable is 0. 879 8801.6.2 Destination Address Ordering 881 882KAME's getaddrinfo(3) supports the destination address ordering 883algorithm described in RFC3484. Getaddrinfo(3) needs to know the 884source address for each destination address and policy entries 885(described in the previous section) for the source and destination 886addresses. To get the source address, the library function opens a 887UDP socket and tries to connect(2) for the destination. To get the 888policy entry, the function issues sysctl(3). 889 8901.7 Jumbo Payload 891 892KAME supports the Jumbo Payload hop-by-hop option used to send IPv6 893packets with payloads longer than 65,535 octets. But since currently 894KAME does not support any physical interface whose MTU is more than 89565,535, such payloads can be seen only on the loopback interface(i.e. 896lo0). 897 898If you want to try jumbo payloads, you first have to reconfigure the 899kernel so that the MTU of the loopback interface is more than 65,535 900bytes; add the following to the kernel configuration file: 901 options "LARGE_LOMTU" #To test jumbo payload 902and recompile the new kernel. 903 904Then you can test jumbo payloads by the ping6 command with -b and -s 905options. The -b option must be specified to enlarge the size of the 906socket buffer and the -s option specifies the length of the packet, 907which should be more than 65,535. For example, type as follows; 908 % ping6 -b 70000 -s 68000 ::1 909 910The IPv6 specification requires that the Jumbo Payload option must not 911be used in a packet that carries a fragment header. If this condition 912is broken, an ICMPv6 Parameter Problem message must be sent to the 913sender. KAME kernel follows the specification, but you cannot usually 914see an ICMPv6 error caused by this requirement. 915 916If KAME kernel receives an IPv6 packet, it checks the frame length of 917the packet and compares it to the length specified in the payload 918length field of the IPv6 header or in the value of the Jumbo Payload 919option, if any. If the former is shorter than the latter, KAME kernel 920discards the packet and increments the statistics. You can see the 921statistics as output of netstat command with `-s -p ip6' option: 922 % netstat -s -p ip6 923 ip6: 924 (snip) 925 1 with data size < data length 926 927So, KAME kernel does not send an ICMPv6 error unless the erroneous 928packet is an actual Jumbo Payload, that is, its packet size is more 929than 65,535 bytes. As described above, KAME kernel currently does not 930support physical interface with such a huge MTU, so it rarely returns an 931ICMPv6 error. 932 933TCP/UDP over jumbogram is not supported at this moment. This is because 934we have no medium (other than loopback) to test this. Contact us if you 935need this. 936 937IPsec does not work on jumbograms. This is due to some specification twists 938in supporting AH with jumbograms (AH header size influences payload length, 939and this makes it real hard to authenticate inbound packet with jumbo payload 940option as well as AH). 941 942There are fundamental issues in *BSD support for jumbograms. We would like to 943address those, but we need more time to finalize the task. To name a few: 944- mbuf pkthdr.len field is typed as "int" in 4.4BSD, so it cannot hold 945 jumbogram with len > 2G on 32bit architecture CPUs. If we would like to 946 support jumbogram properly, the field must be expanded to hold 4G + 947 IPv6 header + link-layer header. Therefore, it must be expanded to at least 948 int64_t (u_int32_t is NOT enough). 949- We mistakingly use "int" to hold packet length in many places. We need 950 to convert them into larger numeric type. It needs a great care, as we may 951 experience overflow during packet length computation. 952- We mistakingly check for ip6_plen field of IPv6 header for packet payload 953 length in various places. We should be checking mbuf pkthdr.len instead. 954 ip6_input() will perform sanity check on jumbo payload option on input, 955 and we can safely use mbuf pkthdr.len afterwards. 956- TCP code needs careful updates in bunch of places, of course. 957 9581.8 Loop prevention in header processing 959 960IPv6 specification allows arbitrary number of extension headers to 961be placed onto packets. If we implement IPv6 packet processing 962code in the way BSD IPv4 code is implemented, kernel stack may 963overflow due to long function call chain. KAME sys/netinet6 code 964is carefully designed to avoid kernel stack overflow. Because of 965this, KAME sys/netinet6 code defines its own protocol switch 966structure, as "struct ip6protosw" (see netinet6/ip6protosw.h). 967 968In addition to this, we restrict the number of extension headers 969(including the IPv6 header) in each incoming packet, in order to 970prevent a DoS attack that tries to send packets with a massive number 971of extension headers. The upper limit can be configured by the sysctl 972value net.inet6.ip6.hdrnestlimit. In particular, if the value is 0, 973the node will allow an arbitrary number of headers. As of writing this 974document, the default value is 50. 975 976IPv4 part (sys/netinet) remains untouched for compatibility. 977Because of this, if you receive IPsec-over-IPv4 packet with massive 978number of IPsec headers, kernel stack may blow up. IPsec-over-IPv6 is okay. 979 9801.9 ICMPv6 981 982After RFC2463 was published, IETF ipngwg has decided to disallow ICMPv6 error 983packet against ICMPv6 redirect, to prevent ICMPv6 storm on a network medium. 984KAME already implements this into the kernel. 985 986RFC2463 requires rate limitation for ICMPv6 error packets generated by a 987node, to avoid possible DoS attacks. KAME kernel implements two rate- 988limitation mechanisms, tunable via sysctl: 989- Minimum time interval between ICMPv6 error packets 990 KAME kernel will generate no more than one ICMPv6 error packet, 991 during configured time interval. net.inet6.icmp6.errratelimit 992 controls the interval (default: disabled). 993- Maximum ICMPv6 error packet-per-second 994 KAME kernel will generate no more than the configured number of 995 packets in one second. net.inet6.icmp6.errppslimit controls the 996 maximum packet-per-second value (default: 200pps) 997Basically, we need to pick values that are suitable against the bandwidth 998of link layer devices directly attached to the node. In some cases the 999default values may not fit well. We are still unsure if the default value 1000is sane or not. Comments are welcome. 1001 10021.10 Applications 1003 1004For userland programming, we support IPv6 socket API as specified in 1005RFC2553/3493, RFC3542 and upcoming internet drafts. 1006 1007TCP/UDP over IPv6 is available and quite stable. You can enjoy "telnet", 1008"ftp", "rlogin", "rsh", "ssh", etc. These applications are protocol 1009independent. That is, they automatically chooses IPv4 or IPv6 1010according to DNS. 1011 10121.11 Kernel Internals 1013 1014 (*) TCP/UDP part is handled differently between operating system platforms. 1015 See 1.12 for details. 1016 1017The current KAME has escaped from the IPv4 netinet logic. While 1018ip_forward() calls ip_output(), ip6_forward() directly calls 1019if_output() since routers must not divide IPv6 packets into fragments. 1020 1021ICMPv6 should contain the original packet as long as possible up to 10221280. UDP6/IP6 port unreach, for instance, should contain all 1023extension headers and the *unchanged* UDP6 and IP6 headers. 1024So, all IP6 functions except TCP6 never convert network byte 1025order into host byte order, to save the original packet. 1026 1027tcp6_input(), udp6_input() and icmp6_input() can't assume that IP6 1028header is preceding the transport headers due to extension 1029headers. So, in6_cksum() was implemented to handle packets whose IP6 1030header and transport header is not continuous. TCP/IP6 nor UDP/IP6 1031header structure don't exist for checksum calculation. 1032 1033To process IP6 header, extension headers and transport headers easily, 1034KAME requires network drivers to store packets in one internal mbuf or 1035one or more external mbufs. A typical old driver prepares two 1036internal mbufs for 100 - 208 bytes data, however, KAME's reference 1037implementation stores it in one external mbuf. 1038 1039"netstat -s -p ip6" tells you whether or not your driver conforms 1040KAME's requirement. In the following example, "cce0" violates the 1041requirement. (For more information, refer to Section 2.) 1042 1043 Mbuf statistics: 1044 317 one mbuf 1045 two or more mbuf:: 1046 lo0 = 8 1047 cce0 = 10 1048 3282 one ext mbuf 1049 0 two or more ext mbuf 1050 1051xxx_ctlinput() calls in_mrejoin() on PRC_IFNEWADDR. We think this is 1052one of 4.4BSD implementation flaws. Since 4.4BSD keeps ia_multiaddrs 1053in in_ifaddr{}, it can't use multicast feature if the interface has no 1054unicast address. So, if an application joins to an interface and then 1055all unicast addresses are removed from the interface, the application 1056can't send/receive any multicast packets. Moreover, if a new unicast 1057address is assigned to the interface, in_mrejoin() must be called. 1058KAME's interfaces, however, have ALWAYS one link-local unicast 1059address. These extensions have thus not been implemented in KAME. 1060 10611.12 IPv4 mapped address and IPv6 wildcard socket 1062 1063RFC2553/3493 describes IPv4 mapped address (3.7) and special behavior 1064of IPv6 wildcard bind socket (3.8). The spec allows you to: 1065- Accept IPv4 connections by AF_INET6 wildcard bind socket. 1066- Transmit IPv4 packet over AF_INET6 socket by using special form of 1067 the address like ::ffff:10.1.1.1. 1068but the spec itself is very complicated and does not specify how the 1069socket layer should behave. 1070Here we call the former one "listening side" and the latter one "initiating 1071side", for reference purposes. 1072 1073Almost all KAME implementations treat tcp/udp port number space separately 1074between IPv4 and IPv6. You can perform wildcard bind on both of the address 1075families, on the same port. 1076 1077There are some OS-platform differences in KAME code, as we use tcp/udp 1078code from different origin. The following table summarizes the behavior. 1079 1080 listening side initiating side 1081 (AF_INET6 wildcard (connection to ::ffff:10.1.1.1) 1082 socket gets IPv4 conn.) 1083 --- --- 1084KAME/BSDI3 not supported not supported 1085KAME/FreeBSD228 not supported not supported 1086KAME/FreeBSD3x configurable supported 1087 default: enabled 1088KAME/FreeBSD4x configurable supported 1089 default: enabled 1090KAME/NetBSD configurable supported 1091 default: disabled 1092KAME/BSDI4 enabled supported 1093KAME/OpenBSD not supported not supported 1094 1095The following sections will give you more details, and how you can 1096configure the behavior. 1097 1098Comments on listening side: 1099 1100It looks that RFC2553/3493 talks too little on wildcard bind issue, 1101specifically on (1) port space issue, (2) failure mode, (3) relationship 1102between AF_INET/INET6 wildcard bind like ordering constraint, and (4) behavior 1103when conflicting socket is opened/closed. There can be several separate 1104interpretation for this RFC which conform to it but behaves differently. 1105So, to implement portable application you should assume nothing 1106about the behavior in the kernel. Using getaddrinfo() is the safest way. 1107Port number space and wildcard bind issues were discussed in detail 1108on ipv6imp mailing list, in mid March 1999 and it looks that there's 1109no concrete consensus (means, up to implementers). You may want to 1110check the mailing list archives. 1111We supply a tool called "bindtest" that explores the behavior of 1112kernel bind(2). The tool will not be compiled by default. 1113 1114If a server application would like to accept IPv4 and IPv6 connections, 1115it should use AF_INET and AF_INET6 socket (you'll need two sockets). 1116Use getaddrinfo() with AI_PASSIVE into ai_flags, and socket(2) and bind(2) 1117to all the addresses returned. 1118By opening multiple sockets, you can accept connections onto the socket with 1119proper address family. IPv4 connections will be accepted by AF_INET socket, 1120and IPv6 connections will be accepted by AF_INET6 socket (NOTE: KAME/BSDI4 1121kernel sometimes violate this - we will fix it). 1122 1123If you try to support IPv6 traffic only and would like to reject IPv4 1124traffic, always check the peer address when a connection is made toward 1125AF_INET6 listening socket. If the address is IPv4 mapped address, you may 1126want to reject the connection. You can check the condition by using 1127IN6_IS_ADDR_V4MAPPED() macro. This is one of the reasons the author of 1128the section (itojun) dislikes special behavior of AF_INET6 wildcard bind. 1129 1130Comments on initiating side: 1131 1132Advise to application implementers: to implement a portable IPv6 application 1133(which works on multiple IPv6 kernels), we believe that the following 1134is the key to the success: 1135- NEVER hardcode AF_INET nor AF_INET6. 1136- Use getaddrinfo() and getnameinfo() throughout the system. 1137 Never use gethostby*(), getaddrby*(), inet_*() or getipnodeby*(). 1138- If you would like to connect to destination, use getaddrinfo() and try 1139 all the destination returned, like telnet does. 1140- Some of the IPv6 stack is shipped with buggy getaddrinfo(). Ship a minimal 1141 working version with your application and use that as last resort. 1142 1143If you would like to use AF_INET6 socket for both IPv4 and IPv6 outgoing 1144connection, you will need tweaked implementation in DNS support libraries, 1145as documented in RFC2553/3493 6.1. KAME libinet6 includes the tweak in 1146getipnodebyname(). Note that getipnodebyname() itself is not recommended as 1147it does not handle scoped IPv6 addresses at all. For IPv6 name resolution 1148getaddrinfo() is the preferred API. getaddrinfo() does not implement the 1149tweak. 1150 1151When writing applications that make outgoing connections, story goes much 1152simpler if you treat AF_INET and AF_INET6 as totally separate address family. 1153{set,get}sockopt issue goes simpler, DNS issue will be made simpler. We do 1154not recommend you to rely upon IPv4 mapped address. 1155 11561.12.1 KAME/BSDI3 and KAME/FreeBSD228 1157 1158The platforms do not support IPv4 mapped address at all (both listening side 1159and initiating side). AF_INET6 and AF_INET sockets are totally separated. 1160 1161Port number space is totally separate between AF_INET and AF_INET6 sockets. 1162 1163It should be noted that KAME/BSDI3 and KAME/FreeBSD228 are not conformant 1164to RFC2553/3493 section 3.7 and 3.8. It is due to code sharing reasons. 1165 11661.12.2 KAME/FreeBSD[34]x 1167 1168KAME/FreeBSD3x and KAME/FreeBSD4x use shared tcp4/6 code (from 1169sys/netinet/tcp*) and shared udp4/6 code (from sys/netinet/udp*). 1170They use unified inpcb/in6pcb structure. 1171 11721.12.2.1 KAME/FreeBSD[34]x, listening side 1173 1174The platform can be configured to support IPv4 mapped address/special 1175AF_INET6 wildcard bind (enabled by default). There is no kernel compilation 1176option to disable it. You can enable/disable the behavior with sysctl 1177(per-node), or setsockopt (per-socket). 1178 1179Wildcard AF_INET6 socket grabs IPv4 connection if and only if the following 1180conditions are satisfied: 1181- there's no AF_INET socket that matches the IPv4 connection 1182- the AF_INET6 socket is configured to accept IPv4 traffic, i.e. 1183 getsockopt(IPV6_V6ONLY) returns 0. 1184 1185(XXX need checking) 1186 11871.12.2.2 KAME/FreeBSD[34]x, initiating side 1188 1189KAME/FreeBSD3x supports outgoing connection to IPv4 mapped address 1190(::ffff:10.1.1.1), if the node is configured to accept IPv4 connections 1191by AF_INET6 socket. 1192 1193(XXX need checking) 1194 11951.12.3 KAME/NetBSD 1196 1197KAME/NetBSD uses shared tcp4/6 code (from sys/netinet/tcp*) and shared 1198udp4/6 code (from sys/netinet/udp*). The implementation is made differently 1199from KAME/FreeBSD[34]x. KAME/NetBSD uses separate inpcb/in6pcb structures, 1200while KAME/FreeBSD[34]x uses merged inpcb structure. 1201 1202It should be noted that the default configuration of KAME/NetBSD is not 1203conformant to RFC2553/3493 section 3.8. It is intentionally turned off by 1204default for security reasons. 1205 1206The platform can be configured to support IPv4 mapped address/special AF_INET6 1207wildcard bind (disabled by default). Kernel behavior can be summarized as 1208follows: 1209- default: special support code will be compiled in, but is disabled by 1210 default. It can be controlled by sysctl (net.inet6.ip6.v6only), 1211 or setsockopt(IPV6_V6ONLY). 1212- add "INET6_BINDV6ONLY": No special support code for AF_INET6 wildcard socket 1213 will be compiled in. AF_INET6 sockets and AF_INET sockets are totally 1214 separate. The behavior is similar to what described in 1.12.1. 1215 1216sysctl setting will affect per-socket configuration at in6pcb creation time 1217only. In other words, per-socket configuration will be copied from sysctl 1218configuration at in6pcb creation time. To change per-socket behavior, you 1219must perform setsockopt or reopen the socket. Change in sysctl configuration 1220will not change the behavior or sockets that are already opened. 1221 12221.12.3.1 KAME/NetBSD, listening side 1223 1224Wildcard AF_INET6 socket grabs IPv4 connection if and only if the following 1225conditions are satisfied: 1226- there's no AF_INET socket that matches the IPv4 connection 1227- the AF_INET6 socket is configured to accept IPv4 traffic, i.e. 1228 getsockopt(IPV6_V6ONLY) returns 0. 1229 1230You cannot bind(2) with IPv4 mapped address. This is a workaround for port 1231number duplicate and other twists. 1232 12331.12.3.2 KAME/NetBSD, initiating side 1234 1235When getsockopt(IPV6_V6ONLY) is 0 for a socket, you can make an outgoing 1236traffic to IPv4 destination over AF_INET6 socket, using IPv4 mapped 1237address destination (::ffff:10.1.1.1). 1238 1239When getsockopt(IPV6_V6ONLY) is 1 for a socket, you cannot use IPv4 mapped 1240address for outgoing traffic. 1241 12421.12.4 KAME/BSDI4 1243 1244KAME/BSDI4 uses NRL-based TCP/UDP stack and inpcb source code, 1245which was derived from NRL IPv6/IPsec stack. We guess it supports IPv4 mapped 1246address and speical AF_INET6 wildcard bind. The implementation is, again, 1247different from other KAME/*BSDs. 1248 12491.12.4.1 KAME/BSDI4, listening side 1250 1251NRL inpcb layer supports special behavior of AF_INET6 wildcard socket. 1252There is no way to disable the behavior. 1253 1254Wildcard AF_INET6 socket grabs IPv4 connection if and only if the following 1255condition is satisfied: 1256- there's no AF_INET socket that matches the IPv4 connection 1257 12581.12.4.2 KAME/BSDI4, initiating side 1259 1260KAME/BSDi4 supports connection initiation to IPv4 mapped address 1261(like ::ffff:10.1.1.1). 1262 12631.12.5 KAME/OpenBSD 1264 1265KAME/OpenBSD uses NRL-based TCP/UDP stack and inpcb source code, 1266which was derived from NRL IPv6/IPsec stack. 1267 1268It should be noted that KAME/OpenBSD is not conformant to RFC2553/3493 section 12693.7 and 3.8. It is intentionally omitted for security reasons. 1270 12711.12.5.1 KAME/OpenBSD, listening side 1272 1273KAME/OpenBSD disables special behavior on AF_INET6 wildcard bind for 1274security reasons (if IPv4 traffic toward AF_INET6 wildcard bind is allowed, 1275access control will become much harder). KAME/BSDI4 uses NRL-based TCP/UDP 1276stack as well, however, the behavior is different due to OpenBSD's security 1277policy. 1278 1279As a result the behavior of KAME/OpenBSD is similar to KAME/BSDI3 and 1280KAME/FreeBSD228 (see 1.12.1 for more detail). 1281 12821.12.5.2 KAME/OpenBSD, initiating side 1283 1284KAME/OpenBSD does not support connection initiation to IPv4 mapped address 1285(like ::ffff:10.1.1.1). 1286 12871.12.6 More issues 1288 1289IPv4 mapped address support adds a big requirement to EVERY userland codebase. 1290Every userland code should check if an AF_INET6 sockaddr contains IPv4 1291mapped address or not. This adds many twists: 1292 1293- Access controls code becomes harder to write. 1294 For example, if you would like to reject packets from 10.0.0.0/8, 1295 you need to reject packets to AF_INET socket from 10.0.0.0/8, 1296 and to AF_INET6 socket from ::ffff:10.0.0.0/104. 1297- If a protocol on top of IPv4 is defined differently with IPv6, we need to be 1298 really careful when we determine which protocol to use. 1299 For example, with FTP protocol, we can not simply use sa_family to determine 1300 FTP command sets. The following example is incorrect: 1301 if (sa_family == AF_INET) 1302 use EPSV/EPRT or PASV/PORT; /*IPv4*/ 1303 else if (sa_family == AF_INET6) 1304 use EPSV/EPRT or LPSV/LPRT; /*IPv6*/ 1305 else 1306 error; 1307 The correct code, with consideration to IPv4 mapped address, would be: 1308 if (sa_family == AF_INET) 1309 use EPSV/EPRT or PASV/PORT; /*IPv4*/ 1310 else if (sa_family == AF_INET6 && IPv4 mapped address) 1311 use EPSV/EPRT or PASV/PORT; /*IPv4 command set on AF_INET6*/ 1312 else if (sa_family == AF_INET6 && !IPv4 mapped address) 1313 use EPSV/EPRT or LPSV/LPRT; /*IPv6*/ 1314 else 1315 error; 1316 It is too much to ask for every body to be careful like this. 1317 The problem is, we are not sure if the above code fragment is perfect for 1318 all situations. 1319- By enabling kernel support for IPv4 mapped address (outgoing direction), 1320 servers on the kernel can be hosed by IPv6 native packet that has IPv4 1321 mapped address in IPv6 header source, and can generate unwanted IPv4 packets. 1322 draft-itojun-ipv6-transition-abuse-01.txt, draft-cmetz-v6ops-v4mapped-api- 1323 harmful-00.txt, and draft-itojun-v6ops-v4mapped-harmful-01.txt 1324 has more on this scenario. 1325 1326Due to the above twists, some of KAME userland programs has restrictions on 1327the use of IPv4 mapped addresses: 1328- rshd/rlogind do not accept connections from IPv4 mapped address. 1329 This is to avoid malicious use of IPv4 mapped address in IPv6 native 1330 packet, to bypass source-address based authentication. 1331- ftp/ftpd assume that you are on dual stack network. IPv4 mapped address 1332 will be decoded in userland, and will be passed to AF_INET sockets 1333 (in other words, ftp/ftpd do not support SIIT environment). 1334 13351.12.7 Interaction with SIIT translator 1336 1337SIIT translator is specified in RFC2765. KAME node cannot become a SIIT 1338translator box, nor SIIT end node (a node in SIIT cloud). 1339 1340To become a SIIT translator box, we need to put additional code for that. 1341We do not have the code in our tree at this moment. 1342 1343There are multiple reasons that we are unable to become SIIT end node. 1344(1) SIIT translators require end nodes in the SIIT cloud to be IPv6-only. 1345Since we are unable to compile INET-less kernel, we are unable to become 1346SIIT end node. (2) As presented in 1.12.6, some of our userland code assumes 1347dual stack network. (3) KAME stack filters out IPv6 packets with IPv4 1348mapped address in the header, to secure non-SIIT case (which is much more 1349common). Effectively KAME node will reject any packets via SIIT translator 1350box. See section 1.14 for more detail about the last item. 1351 1352There are documentation issues too - SIIT document requires very strange 1353things. For example, SIIT document asks IPv6-only (meaning no IPv4 code) 1354node to be able to construct IPv4 IPsec headers. If a node knows how to 1355construct IPv4 IPsec headers, that is not an IPv6-only node, it is a dual-stack 1356node. The requirements imposed in SIIT document contradict with the other 1357part of the document itself. 1358 13591.13 sockaddr_storage 1360 1361When RFC2553 was about to be finalized, there was discussion on how struct 1362sockaddr_storage members are named. One proposal is to prepend "__" to the 1363members (like "__ss_len") as they should not be touched. The other proposal 1364was that don't prepend it (like "ss_len") as we need to touch those members 1365directly. There was no clear consensus on it. 1366 1367As a result, RFC2553 defines struct sockaddr_storage as follows: 1368 struct sockaddr_storage { 1369 u_char __ss_len; /* address length */ 1370 u_char __ss_family; /* address family */ 1371 /* and bunch of padding */ 1372 }; 1373On the contrary, XNET draft defines as follows: 1374 struct sockaddr_storage { 1375 u_char ss_len; /* address length */ 1376 u_char ss_family; /* address family */ 1377 /* and bunch of padding */ 1378 }; 1379 1380In December 1999, it was agreed that RFC2553bis (RFC3493) should pick the 1381latter (XNET) definition. 1382 1383KAME kit prior to December 1999 used RFC2553 definition. KAME kit after 1384December 1999 (including December) will conform to XNET definition, 1385based on RFC3493 discussion. 1386 1387If you look at multiple IPv6 implementations, you will be able to see 1388both definitions. As an userland programmer, the most portable way of 1389dealing with it is to: 1390(1) ensure ss_family and/or ss_len are available on the platform, by using 1391 GNU autoconf, 1392(2) have -Dss_family=__ss_family to unify all occurrences (including header 1393 file) into __ss_family, or 1394(3) never touch __ss_family. cast to sockaddr * and use sa_family like: 1395 struct sockaddr_storage ss; 1396 family = ((struct sockaddr *)&ss)->sa_family 1397 13981.14 Invalid addresses on the wire 1399 1400Some of IPv6 transition technologies embed IPv4 address into IPv6 address. 1401These specifications themselves are fine, however, there can be certain 1402set of attacks enabled by these specifications. Recent specification 1403documents covers up those issues, however, there are already-published RFCs 1404that does not have protection against those (like using source address of 1405::ffff:127.0.0.1 to bypass "reject packet from remote" filter). 1406 1407To name a few, these address ranges can be used to hose an IPv6 implementation, 1408or bypass security controls: 1409- IPv4 mapped address that embeds unspecified/multicast/loopback/broadcast 1410 IPv4 address (if they are in IPv6 native packet header, they are malicious) 1411 ::ffff:0.0.0.0/104 ::ffff:127.0.0.0/104 1412 ::ffff:224.0.0.0/100 ::ffff:255.0.0.0/104 1413- 6to4 (RFC3056) prefix generated from unspecified/multicast/loopback/ 1414 broadcast/private IPv4 address 1415 2002:0000::/24 2002:7f00::/24 2002:e000::/24 1416 2002:ff00::/24 2002:0a00::/24 2002:ac10::/28 1417 2002:c0a8::/32 1418- IPv4 compatible address that embeds unspecified/multicast/loopback/broadcast 1419 IPv4 address (if they are in IPv6 native packet header, they are malicious). 1420 Note that, since KAME doe snot support RFC1933/2893 auto tunnels, KAME nodes 1421 are not vulnerable to these packets. 1422 ::0.0.0.0/104 ::127.0.0.0/104 ::224.0.0.0/100 ::255.0.0.0/104 1423 1424Also, since KAME does not support RFC1933/2893 auto tunnels, seeing IPv4 1425compatible is very rare. You should take caution if you see those on the wire. 1426 1427If we see IPv6 packets with IPv4 mapped address (::ffff:0.0.0.0/96) in the 1428header in dual-stack environment (not in SIIT environment), they indicate 1429that someone is trying to impersonate IPv4 peer. The packet should be dropped. 1430 1431IPv6 specifications do not talk very much about IPv6 unspecified address (::) 1432in the IPv6 source address field. Clarification is in progress. 1433Here are couple of comments: 1434- IPv6 unspecified address can be used in IPv6 source address field, if and 1435 only if we have no legal source address for the node. The legal situations 1436 include, but may not be limited to, (1) MLD while no IPv6 address is assigned 1437 to the node and (2) DAD. 1438- If IPv6 TCP packet has IPv6 unspecified address, it is an attack attempt. 1439 The form can be used as a trigger for TCP DoS attack. KAME code already 1440 filters them out. 1441- The following examples are seemingly illegal. It seems that there's general 1442 consensus among ipngwg for those. (1) Mobile IPv6 home address option, 1443 (2) offlink packets (so routers should not forward them). 1444 KAME implements (2) already. 1445 1446KAME code is carefully written to avoid such incidents. More specifically, 1447KAME kernel will reject packets with certain source/destination address in IPv6 1448base header, or IPv6 routing header. Also, KAME default configuration file 1449is written carefully, to avoid those attacks. 1450 1451draft-itojun-ipv6-transition-abuse-01.txt, draft-cmetz-v6ops-v4mapped-api- 1452harmful-00.txt and draft-itojun-v6ops-v4mapped-harmful-01.txt has more on 1453this issue. 1454 14551.15 Node's required addresses 1456 1457RFC2373 section 2.8 talks about required addresses for an IPv6 1458node. The section talks about how KAME stack manages those required 1459addresses. 1460 14611.15.1 Host case 1462 1463The following items are automatically assigned to the node (or the node will 1464automatically joins the group), at bootstrap time: 1465- Loopback address 1466- All-nodes multicast addresses (ff01::1) 1467 1468The following items will be automatically handled when the interface becomes 1469IFF_UP: 1470- Its link-local address for each interface 1471- Solicited-node multicast address for link-local addresses 1472- Link-local allnodes multicast address (ff02::1) 1473 1474The following items need to be configured manually by ifconfig(8) or prefix(8). 1475Alternatively, these can be autoconfigured by using stateless address 1476autoconfiguration. 1477- Assigned unicast/anycast addresses 1478- Solicited-Node multicast address for assigned unicast address 1479 1480Users can join groups by using appropriate system calls like setsockopt(2). 1481 14821.15.2 Router case 1483 1484In addition to the above, routers needs to handle the following items. 1485 1486The following items need to be configured manually by using ifconfig(8). 1487o The subnet-router anycast addresses for the interfaces it is configured 1488 to act as a router on (prefix::/64) 1489o All other anycast addresses with which the router has been configured 1490 1491The router will join the following multicast group when rtadvd(8) is available 1492for the interface. 1493o All-Routers Multicast Addresses (ff02::2) 1494 1495Routing daemons will join appropriate multicast groups, as necessary, 1496like ff02::9 for RIPng. 1497 1498Users can join groups by using appropriate system calls like setsockopt(2). 1499 15001.16 Advanced API 1501 1502Current KAME kernel implements RFC3542 API. It also implements RFC2292 API, 1503for backward compatibility purposes with *BSD-integrated codebase. 1504KAME tree ships with RFC3542 headers. 1505*BSD-integrated codebase implements either RFC2292, or RFC3542, API. 1506see "COVERAGE" document for detailed implementation status. 1507 1508Here are couple of issues to mention: 1509- *BSD-integrated binaries, compiled for RFC2292, will work on KAME kernel. 1510 For example, OpenBSD 2.7 /sbin/rtsol will work on KAME/openbsd kernel. 1511- KAME binaries, compiled using RFC3542, will not work on *BSD-integrated 1512 kenrel. For example, KAME /usr/local/v6/sbin/rtsol will not work on 1513 OpenBSD 2.7 kernel. 1514- RFC3542 API is not compatible with RFC2292 API. RFC3542 #define symbols 1515 conflict with RFC2292 symbols. Therefore, if you compile programs that 1516 assume RFC2292 API, the compilation itself goes fine, however, the compiled 1517 binary will not work correctly. The problem is not KAME issue, but API 1518 issue. For example, Solaris 8 implements RFC3542 API. If you compile 1519 RFC2292-based code on Solaris 8, the binary can behave strange. 1520 1521There are few (or couple of) incompatible behavior in RFC2292 binary backward 1522compatibility support in KAME tree. To enumerate: 1523- Type 0 routing header lacks support for strict/loose bitmap. 1524 Even if we see packets with "strict" bit set, those bits will not be made 1525 visible to the userland. 1526 Background: RFC2292 document is based on RFC1883 IPv6, and it uses 1527 strict/loose bitmap. RFC3542 document is based on RFC2460 IPv6, and it has 1528 no strict/loose bitmap (it was removed from RFC2460). KAME tree obeys 1529 RFC2460 IPv6, and lacks support for strict/loose bitmap. 1530 1531The RFC3542 documents leave some particular cases unspecified. The 1532KAME implementation treats them as follows: 1533- The IPV6_DONTFRAG and IPV6_RECVPATHMTU socket options for TCP 1534 sockets are ignored. That is, the setsocktopt() call will succeed 1535 but the specified value will have no effect. 1536 15371.17 DNS resolver 1538 1539KAME ships with modified DNS resolver, in libinet6.a. 1540libinet6.a has a couple of extensions against libc DNS resolver: 1541- Can take "options insecure1" and "options insecure2" in /etc/resolv.conf, 1542 which toggles RES_INSECURE[12] option flag bit. 1543- EDNS0 receive buffer size notification support. It can be enabled by 1544 "options edns0" in /etc/resolv.conf. See USAGE for details. 1545- IPv6 transport support (queries/responses over IPv6). Most of BSD official 1546 releases now has it already. 1547- Partial A6 chain chasing/DNAME/bit string label support (KAME/BSDI4). 1548 1549 15502. Network Drivers 1551 1552KAME requires three items to be added into the standard drivers: 1553 1554(1) (freebsd[234] and bsdi[34] only) mbuf clustering requirement. 1555 In this stable release, we changed MINCLSIZE into MHLEN+1 for all the 1556 operating systems in order to make all the drivers behave as we expect. 1557 1558(2) multicast. If "ifmcstat" yields no multicast group for a 1559 interface, that interface has to be patched. 1560 1561To avoid troubles, we suggest you to comment out the device drivers 1562for unsupported/unnecessary cards, from the kernel configuration file. 1563If you accidentally enable unsupported drivers, some of the userland 1564tools may not work correctly (routing daemons are typical example). 1565 1566In the following sections, "official support" means that KAME developers 1567are using that ethernet card/driver frequently. 1568 1569(NOTE: In the past we required all pcmcia drivers to have a call to 1570in6_ifattach(). We have no such requirement any more) 1571 15722.1 FreeBSD 2.2.x-RELEASE 1573 1574Here is a list of FreeBSD 2.2.x-RELEASE drivers and its conditions: 1575 1576 driver mbuf(1) multicast(2) official support? 1577 --- --- --- --- 1578 (Ethernet) 1579 ar looks ok - - 1580 cnw ok ok yes (*) 1581 ed ok ok yes 1582 ep ok ok yes 1583 fe ok ok yes 1584 sn looks ok - - (*) 1585 vx looks ok - - 1586 wlp ok ok - (*) 1587 xl ok ok yes 1588 zp ok ok - 1589 (FDDI) 1590 fpa looks ok ? - 1591 (ATM) 1592 en ok ok yes 1593 (Serial) 1594 lp ? - not work 1595 sl ? - not work 1596 sr looks ok ok - (**) 1597 1598You may want to add an invocation of "rtsol" in "/etc/pccard_ether", 1599if you are using notebook computers and PCMCIA ethernet card. 1600 1601(*) These drivers are distributed with PAO (http://www.jp.freebsd.org/PAO/). 1602 1603(**) There was some report says that, if you make sr driver up and down and 1604then up, the kernel may hang up. We have disabled frame-relay support from 1605sr driver and after that this looks to be working fine. If you need 1606frame-relay support to come back, please contact KAME developers. 1607 16082.2 BSD/OS 3.x 1609 1610The following lists BSD/OS 3.x device drivers and its conditions: 1611 1612 driver mbuf(1) multicast(2) official support? 1613 --- --- --- --- 1614 (Ethernet) 1615 cnw ok ok yes 1616 de ok ok - 1617 df ok ok - 1618 eb ok ok - 1619 ef ok ok yes 1620 exp ok ok - 1621 mz ok ok yes 1622 ne ok ok yes 1623 we ok ok - 1624 (FDDI) 1625 fpa ok ok - 1626 (ATM) 1627 en maybe ok - 1628 (Serial) 1629 ntwo ok ok yes 1630 sl ? - not work 1631 appp ? - not work 1632 1633You may want to use "@insert" directive in /etc/pccard.conf to invoke 1634"rtsol" command right after dynamic insertion of PCMCIA ethernet cards. 1635 16362.3 NetBSD 1637 1638The following table lists the network drivers we have tried so far. 1639 1640 driver mbuf(1) multicast(2) official support? 1641 --- --- --- --- 1642 (Ethernet) 1643 awi pcmcia/i386 ok ok - 1644 bah zbus/amiga NG(*) 1645 cnw pcmcia/i386 ok ok yes 1646 ep pcmcia/i386 ok ok - 1647 fxp pci/i386 ok(*2) ok - 1648 tlp pci/i386 ok ok - 1649 le sbus/sparc ok ok yes 1650 ne pci/i386 ok ok yes 1651 ne pcmcia/i386 ok ok yes 1652 rtk pci/i386 ok ok - 1653 wi pcmcia/i386 ok ok yes 1654 (ATM) 1655 en pci/i386 ok ok - 1656 1657(*) This may need some fix, but I'm not sure what arcnet interfaces assume... 1658 16592.4 FreeBSD 3.x-RELEASE 1660 1661Here is a list of FreeBSD 3.x-RELEASE drivers and its conditions: 1662 1663 driver mbuf(1) multicast(2) official support? 1664 --- --- --- --- 1665 (Ethernet) 1666 cnw ok ok -(*) 1667 ed ? ok - 1668 ep ok ok - 1669 fe ok ok yes 1670 fxp ?(**) 1671 lnc ? ok - 1672 sn ? ? -(*) 1673 wi ok ok yes 1674 xl ? ok - 1675 1676(*) These drivers are distributed with PAO as PAO3 1677 (http://www.jp.freebsd.org/PAO/). 1678(**) there were trouble reports with multicast filter initialization. 1679 1680More drivers will just simply work on KAME FreeBSD 3.x-RELEASE but have not 1681been checked yet. 1682 16832.5 FreeBSD 4.x-RELEASE 1684 1685Here is a list of FreeBSD 4.x-RELEASE drivers and its conditions: 1686 1687 driver multicast 1688 --- --- 1689 (Ethernet) 1690 lnc/vmware ok 1691 16922.6 OpenBSD 2.x 1693 1694Here is a list of OpenBSD 2.x drivers and its conditions: 1695 1696 driver mbuf(1) multicast(2) official support? 1697 --- --- --- --- 1698 (Ethernet) 1699 de pci/i386 ok ok yes 1700 fxp pci/i386 ?(*) 1701 le sbus/sparc ok ok yes 1702 ne pci/i386 ok ok yes 1703 ne pcmcia/i386 ok ok yes 1704 wi pcmcia/i386 ok ok yes 1705 1706(*) There seem to be some problem in driver, with multicast filter 1707configuration. This happens with certain revision of chipset on the card. 1708Should be fixed by now by workaround in sys/net/if.c, but still not sure. 1709 17102.7 BSD/OS 4.x 1711 1712The following lists BSD/OS 4.x device drivers and its conditions: 1713 1714 driver mbuf(1) multicast(2) official support? 1715 --- --- --- --- 1716 (Ethernet) 1717 de ok ok yes 1718 exp (*) 1719 1720You may want to use "@insert" directive in /etc/pccard.conf to invoke 1721"rtsol" command right after dynamic insertion of PCMCIA ethernet cards. 1722 1723(*) exp driver has serious conflict with KAME initialization sequence. 1724A workaround is committed into sys/i386/pci/if_exp.c, and should be okay by now. 1725 1726 17273. Translator 1728 1729We categorize IPv4/IPv6 translator into 4 types. 1730 1731Translator A --- It is used in the early stage of transition to make 1732it possible to establish a connection from an IPv6 host in an IPv6 1733island to an IPv4 host in the IPv4 ocean. 1734 1735Translator B --- It is used in the early stage of transition to make 1736it possible to establish a connection from an IPv4 host in the IPv4 1737ocean to an IPv6 host in an IPv6 island. 1738 1739Translator C --- It is used in the late stage of transition to make it 1740possible to establish a connection from an IPv4 host in an IPv4 island 1741to an IPv6 host in the IPv6 ocean. 1742 1743Translator D --- It is used in the late stage of transition to make it 1744possible to establish a connection from an IPv6 host in the IPv6 ocean 1745to an IPv4 host in an IPv4 island. 1746 1747KAME provides an TCP relay translator for category A. This is called 1748"FAITH". We also provide IP header translator for category A. 1749 17503.1 FAITH TCP relay translator 1751 1752FAITH system uses TCP relay daemon called "faithd" helped by the KAME kernel. 1753FAITH will reserve an IPv6 address prefix, and relay TCP connection 1754toward that prefix to IPv4 destination. 1755 1756For example, if the reserved IPv6 prefix is 3ffe:0501:0200:ffff::, and 1757the IPv6 destination for TCP connection is 3ffe:0501:0200:ffff::163.221.202.12, 1758the connection will be relayed toward IPv4 destination 163.221.202.12. 1759 1760 destination IPv4 node (163.221.202.12) 1761 ^ 1762 | IPv4 tcp toward 163.221.202.12 1763 FAITH-relay dual stack node 1764 ^ 1765 | IPv6 TCP toward 3ffe:0501:0200:ffff::163.221.202.12 1766 source IPv6 node 1767 1768faithd must be invoked on FAITH-relay dual stack node. 1769 1770For more details, consult kame/kame/faithd/README and RFC3142. 1771 17723.2 IPv6-to-IPv4 header translator 1773 1774(to be written) 1775 1776 17774. IPsec 1778 1779IPsec is implemented as the following three components. 1780 1781(1) Policy Management 1782(2) Key Management 1783(3) AH, ESP and IPComp handling in kernel 1784 1785Note that KAME/OpenBSD does NOT include support for KAME IPsec code, 1786as OpenBSD team has their home-brew IPsec stack and they have no plan 1787to replace it. IPv6 support for IPsec is, therefore, lacking on KAME/OpenBSD. 1788 1789http://www.netbsd.org/Documentation/network/ipsec/ has more information 1790including usage examples. 1791 17924.1 Policy Management 1793 1794The kernel implements experimental policy management code. There are two ways 1795to manage security policy. One is to configure per-socket policy using 1796setsockopt(3). In this cases, policy configuration is described in 1797ipsec_set_policy(3). The other is to configure kernel packet filter-based 1798policy using PF_KEY interface, via setkey(8). 1799 1800The policy entry will be matched in order. The order of entries makes 1801difference in behavior. 1802 18034.2 Key Management 1804 1805The key management code implemented in this kit (sys/netkey) is a 1806home-brew PFKEY v2 implementation. This conforms to RFC2367. 1807 1808The home-brew IKE daemon, "racoon" is included in the kit (kame/kame/racoon, 1809or usr.sbin/racoon). 1810Basically you'll need to run racoon as daemon, then setup a policy 1811to require keys (like ping -P 'out ipsec esp/transport//use'). 1812The kernel will contact racoon daemon as necessary to exchange keys. 1813 1814In IKE spec, there's ambiguity about interpretation of "tunnel" proposal. 1815For example, if we would like to propose the use of following packet: 1816 IP AH ESP IP payload 1817some implementation proposes it as "AH transport and ESP tunnel", since 1818this is more logical from packet construction point of view. Some 1819implementation proposes it as "AH tunnel and ESP tunnel". 1820Racoon follows the latter route (previously it followed the former, and 1821the latter interpretation seems to be popular/consensus). 1822This raises real interoperability issue. We hope this to be resolved quickly. 1823 1824racoon does not implement byte lifetime for both phase 1 and phase 2 1825(RFC2409 page 35, Life Type = kilobytes). 1826 18274.3 AH and ESP handling 1828 1829IPsec module is implemented as "hooks" to the standard IPv4/IPv6 1830processing. When sending a packet, ip{,6}_output() checks if ESP/AH 1831processing is required by checking if a matching SPD (Security 1832Policy Database) is found. If ESP/AH is needed, 1833{esp,ah}{4,6}_output() will be called and mbuf will be updated 1834accordingly. When a packet is received, {esp,ah}4_input() will be 1835called based on protocol number, i.e. (*inetsw[proto])(). 1836{esp,ah}4_input() will decrypt/check authenticity of the packet, 1837and strips off daisy-chained header and padding for ESP/AH. It is 1838safe to strip off the ESP/AH header on packet reception, since we 1839will never use the received packet in "as is" form. 1840 1841By using ESP/AH, TCP4/6 effective data segment size will be affected by 1842extra daisy-chained headers inserted by ESP/AH. Our code takes care of 1843the case. 1844 1845Basic crypto functions can be found in directory "sys/crypto". ESP/AH 1846transform are listed in {esp,ah}_core.c with wrapper functions. If you 1847wish to add some algorithm, add wrapper function in {esp,ah}_core.c, and 1848add your crypto algorithm code into sys/crypto. 1849 1850Tunnel mode works basically fine, but comes with the following restrictions: 1851- You cannot run routing daemon across IPsec tunnel, since we do not model 1852 IPsec tunnel as pseudo interfaces. 1853- Authentication model for AH tunnel must be revisited. We'll need to 1854 improve the policy management engine, eventually. 1855- Path MTU discovery does not work across IPv6 IPsec tunnel gateway due to 1856 insufficient code. 1857 1858AH specification does not talk much about "multiple AH on a packet" case. 1859We incrementally compute AH checksum, from inside to outside. Also, we 1860treat inner AH to be immutable. 1861For example, if we are to create the following packet: 1862 IP AH1 AH2 AH3 payload 1863we do it incrementally. As a result, we get crypto checksums like below: 1864 AH3 has checksum against "IP AH3' payload". 1865 where AH3' = AH3 with checksum field filled with 0. 1866 AH2 has checksum against "IP AH2' AH3 payload". 1867 AH1 has checksum against "IP AH1' AH2 AH3 payload", 1868Also note that AH3 has the smallest sequence number, and AH1 has the largest 1869sequence number. 1870 1871To avoid traffic analysis on shorter packets, ESP output logic supports 1872random length padding. By setting net.inet.ipsec.esp_randpad (or 1873net.inet6.ipsec6.esp_randpad) to positive value N, you can ask the kernel 1874to randomly pad packets shorter than N bytes, to random length smaller than 1875or equal to N. Note that N does not include ESP authentication data length. 1876Also note that the random padding is not included in TCP segment 1877size computation. Negative value will turn off the functionality. 1878Recommended value for N is like 128, or 256. If you use a too big number 1879as N, you may experience inefficiency due to fragmented packets. 1880 18814.4 IPComp handling 1882 1883IPComp stands for IP payload compression protocol. This is aimed for 1884payload compression, not the header compression like PPP VJ compression. 1885This may be useful when you are using slow serial link (say, cell phone) 1886with powerful CPU (well, recent notebook PCs are really powerful...). 1887The protocol design of IPComp is very similar to IPsec, though it was 1888defined separately from IPsec itself. 1889 1890Here are some points to be noted: 1891- IPComp is treated as part of IPsec protocol suite, and SPI and 1892 CPI space is unified. Spec says that there's no relationship 1893 between two so they are assumed to be separate in specs. 1894- IPComp association (IPCA) is kept in SAD. 1895- It is possible to use well-known CPI (CPI=2 for DEFLATE for example), 1896 for outbound/inbound packet, but for indexing purposes one element from 1897 SPI/CPI space will be occupied anyway. 1898- pfkey is modified to support IPComp. However, there's no official 1899 SA type number assignment yet. Portability with other IPComp 1900 stack is questionable (anyway, who else implement IPComp on UN*X?). 1901- Spec says that IPComp output processing must be performed before AH/ESP 1902 output processing, to achieve better compression ratio and "stir" data 1903 stream before encryption. The most meaningful processing order is: 1904 (1) compress payload by IPComp, (2) encrypt payload by ESP, then (3) attach 1905 authentication data by AH. 1906 However, with manual SPD setting, you are able to violate the ordering 1907 (KAME code is too generic, maybe). Also, it is just okay to use IPComp 1908 alone, without AH/ESP. 1909- Though the packet size can be significantly decreased by using IPComp, no 1910 special consideration is made about path MTU (spec talks nothing about MTU 1911 consideration). IPComp is designed for serial links, not ethernet-like 1912 medium, it seems. 1913- You can change compression ratio on outbound packet, by changing 1914 deflate_policy in sys/netinet6/ipcomp_core.c. You can also change outbound 1915 history buffer size by changing deflate_window_out in the same source code. 1916 (should it be sysctl accessible, or per-SAD configurable?) 1917- Tunnel mode IPComp is not working right. KAME box can generate tunnelled 1918 IPComp packet, however, cannot accept tunneled IPComp packet. 1919- You can negotiate IPComp association with racoon IKE daemon. 1920- KAME code does not attach Adler32 checksum to compressed data. 1921 see ipsec wg mailing list discussion in Jan 2000 for details. 1922 19234.5 Conformance to RFCs and IDs 1924 1925The IPsec code in the kernel conforms (or, tries to conform) to the 1926following standards: 1927 "old IPsec" specification documented in rfc182[5-9].txt 1928 "new IPsec" specification documented in: 1929 rfc240[1-6].txt rfc241[01].txt rfc2451.txt rfc3602.txt 1930 IPComp: 1931 RFC2393: IP Payload Compression Protocol (IPComp) 1932IKE specifications (rfc240[7-9].txt) are implemented in userland 1933as "racoon" IKE daemon. 1934 1935Currently supported algorithms are: 1936 old IPsec AH 1937 null crypto checksum (no document, just for debugging) 1938 keyed MD5 with 128bit crypto checksum (rfc1828.txt) 1939 keyed SHA1 with 128bit crypto checksum (no document) 1940 HMAC MD5 with 128bit crypto checksum (rfc2085.txt) 1941 HMAC SHA1 with 128bit crypto checksum (no document) 1942 HMAC RIPEMD160 with 128bit crypto checksum (no document) 1943 old IPsec ESP 1944 null encryption (no document, similar to rfc2410.txt) 1945 DES-CBC mode (rfc1829.txt) 1946 new IPsec AH 1947 null crypto checksum (no document, just for debugging) 1948 keyed MD5 with 96bit crypto checksum (no document) 1949 keyed SHA1 with 96bit crypto checksum (no document) 1950 HMAC MD5 with 96bit crypto checksum (rfc2403.txt 1951 HMAC SHA1 with 96bit crypto checksum (rfc2404.txt) 1952 HMAC SHA2-256 with 96bit crypto checksum (draft-ietf-ipsec-ciph-sha-256-00.txt) 1953 HMAC SHA2-384 with 96bit crypto checksum (no document) 1954 HMAC SHA2-512 with 96bit crypto checksum (no document) 1955 HMAC RIPEMD160 with 96bit crypto checksum (RFC2857) 1956 AES XCBC MAC with 96bit crypto checksum (RFC3566) 1957 new IPsec ESP 1958 null encryption (rfc2410.txt) 1959 DES-CBC with derived IV 1960 (draft-ietf-ipsec-ciph-des-derived-01.txt, draft expired) 1961 DES-CBC with explicit IV (rfc2405.txt) 1962 3DES-CBC with explicit IV (rfc2451.txt) 1963 BLOWFISH CBC (rfc2451.txt) 1964 CAST128 CBC (rfc2451.txt) 1965 RIJNDAEL/AES CBC (rfc3602.txt) 1966 AES counter mode (rfc3686.txt) 1967 1968 each of the above can be combined with new IPsec AH schemes for 1969 ESP authentication. 1970 IPComp 1971 RFC2394: IP Payload Compression Using DEFLATE 1972 1973The following algorithms are NOT supported: 1974 old IPsec AH 1975 HMAC MD5 with 128bit crypto checksum + 64bit replay prevention 1976 (rfc2085.txt) 1977 keyed SHA1 with 160bit crypto checksum + 32bit padding (rfc1852.txt) 1978 1979The key/policy management API is based on the following document, with fair 1980amount of extensions: 1981 RFC2367: PF_KEY key management API 1982 19834.6 ECN consideration on IPsec tunnels 1984 1985KAME IPsec implements ECN-friendly IPsec tunnel, described in 1986draft-ietf-ipsec-ecn-02.txt. 1987Normal IPsec tunnel is described in RFC2401. On encapsulation, 1988IPv4 TOS field (or, IPv6 traffic class field) will be copied from inner 1989IP header to outer IP header. On decapsulation outer IP header 1990will be simply dropped. The decapsulation rule is not compatible 1991with ECN, since ECN bit on the outer IP TOS/traffic class field will be 1992lost. 1993To make IPsec tunnel ECN-friendly, we should modify encapsulation 1994and decapsulation procedure. This is described in 1995draft-ietf-ipsec-ecn-02.txt, chapter 3.3. 1996 1997KAME IPsec tunnel implementation can give you three behaviors, by setting 1998net.inet.ipsec.ecn (or net.inet6.ipsec6.ecn) to some value: 1999- RFC2401: no consideration for ECN (sysctl value -1) 2000- ECN forbidden (sysctl value 0) 2001- ECN allowed (sysctl value 1) 2002Note that the behavior is configurable in per-node manner, not per-SA manner 2003(draft-ietf-ipsec-ecn-02 wants per-SA configuration, but it looks too much 2004for me). 2005 2006The behavior is summarized as follows (see source code for more detail): 2007 2008 encapsulate decapsulate 2009 --- --- 2010RFC2401 copy all TOS bits drop TOS bits on outer 2011 from inner to outer. (use inner TOS bits as is) 2012 2013ECN forbidden copy TOS bits except for ECN drop TOS bits on outer 2014 (masked with 0xfc) from inner (use inner TOS bits as is) 2015 to outer. set ECN bits to 0. 2016 2017ECN allowed copy TOS bits except for ECN use inner TOS bits with some 2018 CE (masked with 0xfe) from change. if outer ECN CE bit 2019 inner to outer. is 1, enable ECN CE bit on 2020 set ECN CE bit to 0. the inner. 2021 2022General strategy for configuration is as follows: 2023- if both IPsec tunnel endpoint are capable of ECN-friendly behavior, 2024 you'd better configure both end to "ECN allowed" (sysctl value 1). 2025- if the other end is very strict about TOS bit, use "RFC2401" 2026 (sysctl value -1). 2027- in other cases, use "ECN forbidden" (sysctl value 0). 2028The default behavior is "ECN forbidden" (sysctl value 0). 2029 2030For more information, please refer to: 2031 draft-ietf-ipsec-ecn-02.txt 2032 RFC2481 (Explicit Congestion Notification) 2033 KAME sys/netinet6/{ah,esp}_input.c 2034 2035(Thanks goes to Kenjiro Cho <kjc@csl.sony.co.jp> for detailed analysis) 2036 20374.7 Interoperability 2038 2039IPsec, IPComp (in kernel) and IKE (in userland as "racoon") has been tested 2040at several interoperability test events, and it is known to interoperate 2041with many other implementations well. Also, KAME IPsec has quite wide 2042coverage for IPsec crypto algorithms documented in RFC (we do not cover 2043algorithms with intellectual property issues, though). 2044 2045Here are (some of) platforms we have tested IPsec/IKE interoperability 2046in the past, no particular order. Note that both ends (KAME and 2047others) may have modified their implementation, so use the following 2048list just for reference purposes. 2049 6WIND, ACC, Allied-telesis, Altiga, Ashley-laurent (vpcom.com), 2050 BlueSteel, CISCO IOS, Checkpoint FW-1, Compaq Tru54 UNIX 2051 X5.1B-BL4, Cryptek, Data Fellows (F-Secure), Ericsson, 2052 F-Secure VPN+ 5.40, Fitec, Fitel, FreeS/WAN, HITACHI, HiFn, 2053 IBM AIX 5.1, III, IIJ (fujie stack), Intel Canada, Intel 2054 Packet Protect, MEW NetCocoon, MGCS, Microsoft WinNT/2000/XP, 2055 NAI PGPnet, NEC IX5000, NIST (linux IPsec + plutoplus), 2056 NetLock, Netoctave, Netopia, Netscreen, Nokia EPOC, Nortel 2057 GatewayController/CallServer 2000 (not released yet), 2058 NxNetworks, OpenBSD isakmpd on OpenBSD, Oullim information 2059 technologies SECUREWORKS VPN gateway 3.0, Pivotal, RSA, 2060 Radguard, RapidStream, RedCreek, Routerware, SSH, SecGo 2061 CryptoIP v3, Secure Computing, Soliton, Sun Solaris 8, 2062 TIS/NAI Gauntret, Toshiba, Trilogy AdmitOne 2.6, Trustworks 2063 TrustedClient v3.2, USAGI linux, VPNet, Yamaha RT series, 2064 ZyXEL 2065 2066Here are (some of) platforms we have tested IPComp/IKE interoperability 2067in the past, in no particular order. 2068 Compaq, IRE, SSH, NetLock, FreeS/WAN, F-Secure VPN+ 5.40 2069 2070VPNC (vpnc.org) provides IPsec conformance tests, using KAME and OpenBSD 2071IPsec/IKE implementations. Their test results are available at 2072http://www.vpnc.org/conformance.html, and it may give you more idea 2073about which implementation interoperates with KAME IPsec/IKE implementation. 2074 20754.8 Operations with IPsec tunnel mode 2076 2077First of all, IPsec tunnel is a very hairy thing. It seems to do a neat thing 2078like VPN configuration or secure remote accesses, however, it comes with lots 2079of architectural twists. 2080 2081RFC2401 defines IPsec tunnel mode, within the context of IPsec. RFC2401 2082defines tunnel mode packet encapsulation/decapsulation on its own, and 2083does not refer other tunnelling specifications. Since RFC2401 advocates 2084filter-based SPD database matches, it would be natural for us to implement 2085IPsec tunnel mode as filters - not as pseudo interfaces. 2086 2087There are some people who are trying to separate IPsec "tunnel mode" from 2088the IPsec itself. They would like to implement IPsec transport mode only, 2089and combine it with tunneling pseudo devices. The prime example is found 2090in draft-touch-ipsec-vpn-01.txt. However, if you really define pseudo 2091interfaces separately from IPsec, IKE daemons would need to negotiate 2092transport mode SAs, instead of tunnel mode SAs. Therefore, we cannot 2093really mix RFC2401-based interpretation and draft-touch-ipsec-vpn-01.txt 2094interpretation. 2095 2096The KAME stack implements can be configured in two ways. You may need 2097to recompile your kernel to switch the behavior. 2098- RFC2401 IPsec tunnel mode approach (4.8.1) 2099- draft-touch-ipsec-vpn approach (4.8.2) 2100 Works in all kernel configuration, but racoon(8) may not interoperate. 2101 2102There are pros and cons on these approaches: 2103 2104RFC2401 IPsec tunnel mode (filter-like) approach 2105 PRO: SPD lookup fits nicely with packet filters (if you integrate them) 2106 CON: cannot run routing daemons across IPsec tunnels 2107 CON: it is very hard to control source address selection on originating 2108 cases 2109 ???: IPv6 scope zone is kept the same 2110draft-touch-ipsec-vpn (transportmode + Pseudo-interface) approach 2111 PRO: run routing daemons across IPsec tunnels 2112 PRO: source address selection can be done normally, by looking at 2113 IPsec tunnel pseudo devices 2114 CON: on outbound, possibility of infinite loops if routing setup 2115 is wrong 2116 CON: due to differences in encap/decap logic from RFC2401, it may not 2117 interoperate with very picky RFC2401 implementations 2118 (those who check TOS bits, for example) 2119 CON: cannot negotiate IKE with other IPsec tunnel-mode devices 2120 (the other end has to implement 2121 ???: IPv6 scope zone is likely to be different from the real ethernet 2122 interface 2123 2124The recommendation is different depending on the situation you have: 2125- use draft-touch-ipsec-vpn if you have the control over the other end. 2126 this one is the best in terms of simplicity. 2127- if the other end is normal IPsec device with RFC2401 implementation, 2128 you need to use RFC2401, otherwise you won't be able to run IKE. 2129- use RFC2401 approach if you just want to forward packets back and forth 2130 and there's no plan to use IPsec gateway itself as an originating device. 2131 21324.8.1 RFC2401 IPsec tunnel mode approach 2133 2134To configure your device as RFC2401 IPsec tunnel mode endpoint, you will 2135use "tunnel" keyword in setkey(8) "spdadd" directives. Let us assume the 2136following topology (A and B could be a network, like prefix/length): 2137 2138 ((((((((((((The internet)))))))))))) 2139 | | 2140 |C (global) |D 2141 your device peer's device 2142 |A (private) |B 2143 ==+===== VPN net ==+===== VPN net 2144 2145The policy configuration directive is like this. You will need manual 2146SAs, or IKE daemon, for actual encryption: 2147 2148 # setkey -c <<EOF 2149 spdadd A B any -P out ipsec esp/tunnel/C-D/use; 2150 spdadd B A any -P in ipsec esp/tunnel/D-C/use; 2151 ^D 2152 2153The inbound/outbound traffic is monitored/captured by SPD engine, which works 2154just like packet filters. 2155 2156With this, forwarding case should work flawlessly. However, troubles arise 2157when you have one of the following requirements: 2158- When you originate traffic from your VPN gateway device to VPN net on the 2159 other end (like B), you want your source address to be A (private side) 2160 so that the traffic would be protected by the policy. 2161 With this approach, however, the source address selection logic follows 2162 normal routing table, and C (global side) will be picked for any outgoing 2163 traffic, even if the destination is B. The resulting packet will be like 2164 this: 2165 IP[C -> B] payload 2166 and will not match the policy (= sent in clear). 2167- When you want to run routing protocols on top of the IPsec tunnel, it is 2168 not possible. As there is no pseudo device that identifies the IPsec tunnel, 2169 you cannot identify where the routing information came from. As a result, 2170 you can't run routing daemons. 2171 21724.8.2 draft-touch-ipsec-vpn approach 2173 2174With this approach, you will configure gif(4) tunnel interfaces, as well as 2175IPsec transport mode SAs. 2176 2177 # gifconfig gif0 C D 2178 # ifconfig gif0 A B 2179 # setkey -c <<EOF 2180 spdadd C D any -P out ipsec esp/transport//use; 2181 spdadd D C any -P in ipsec esp/transport//use; 2182 ^D 2183 2184Since we have a pseudo-interface "gif0", and it affects the routes and 2185the source address selection logic, we can have source address A, for 2186packets originated by the VPN gateway to B (and the VPN cloud). 2187We can also exchange routing information over the tunnel (gif0), as the tunnel 2188is represented as a pseudo interface (dynamic routes points to the 2189pseudo interface). 2190 2191There is a big drawbacks, however; with this, you can use IKE if and only if 2192the other end is using draft-touch-ipsec-vpn approach too. Since racoon(8) 2193grabs phase 2 IKE proposals from the kernel SPD database, you will be 2194negotiating IPsec transport-mode SAs with the other end, not tunnel-mode SAs. 2195Also, since the encapsulation mechanism is different from RFC2401, you may not 2196be able to interoperate with a picky RFC2401 implementations - if the other 2197end checks certain outer IP header fields (like TOS), you will not be able to 2198interoperate. 2199 2200 22015. ALTQ 2202 2203KAME kit includes ALTQ, which supports FreeBSD3, FreeBSD4, FreeBSD5 2204NetBSD. OpenBSD has ALTQ merged into pf and its ALTQ code is not 2205compatible with other platforms so that KAME's ALTQ is not used for 2206OpenBSD. For BSD/OS, ALTQ does not work. 2207ALTQ in KAME supports IPv6. 2208(actually, ALTQ is developed on KAME repository since ALTQ 2.1 - Jan 2000) 2209 2210ALTQ occupies single character device number. For FreeBSD, it is officially 2211allocated. For OpenBSD and NetBSD, we use the number which is not 2212currently allocated (will eventually get an official number). 2213The character device is enabled for i386 architecture only. To enable and 2214compile ALTQ-ready kernel for other architectures, take the following steps: 2215- assume that your architecture is FOOBAA. 2216- modify sys/arch/FOOBAA/FOOBAA/conf.c (or somewhere that defines cdevsw), 2217 to include a line for ALTQ. look at sys/arch/i386/i386/conf.c for 2218 example. The major number must be same as i386 case. 2219- copy kernel configuration file (like ALTQ.v6 or GENERIC.v6) from i386, 2220 and modify accordingly. 2221- build a kernel. 2222- before building userland, change netbsd/{lib,usr.sbin,usr.bin}/Makefile 2223 (or openbsd/foobaa) so that it will visit altq-related sub directories. 2224 2225 22266. Mobile IPv6 2227 22286.1 KAME node as correspondent node 2229 2230Default installation recognizes home address option (in destination 2231options header). No sub-options are supported. Interaction with 2232IPsec, and/or 2292bis API, needs further study. 2233 22346.2 KAME node as home agent/mobile node 2235 2236KAME kit includes Ericsson mobile-ip6 code. The integration is just started 2237(in Feb 2000), and we will need some more time to integrate it better. 2238 2239See kame/mip6config/{QUICKSTART,README_MIP6.txt} for more details. 2240 2241The Ericsson code implements revision 09 of the mobile-ip6 draft. There 2242are other implementations available: 2243 NEC: http://www.6bone.nec.co.jp/mipv6/internal-dist/ (-13 draft) 2244 SFC: http://neo.sfc.wide.ad.jp/~mip6/ (-13 draft) 2245 22467. Coding style 2247 2248The KAME developers basically do not make a bother about coding 2249style. However, there is still some agreement on the style, in order 2250to make the distributed development smooth. 2251 2252- follow *BSD KNF where possible. note: there are multiple KNF standards. 2253- the tab character should be 8 columns wide (tabstops are at 8, 16, 24, ... 2254 column). With vi, use ":set ts=8 sw=8". 2255 With GNU Emacs 20 and later, the easiest way is to use the "bsd" style of 2256 cc-mode with the variable "c-basic-offset" being 8; 2257 (add-hook 'c-mode-common-hook 2258 (function 2259 (lambda () 2260 (c-set-style "bsd") 2261 (setq c-basic-offset 8) ; XXX for Emacs 20 only 2262 ))) 2263 The "bsd" style in GNU Emacs 21 sets the variable to 8 by default, 2264 so the line marked by "XXX" is not necessary if you only use GNU 2265 Emacs 21. 2266- each line should be within 80 characters. 2267- keep a single open/close bracket in a comment such as in the following 2268 line: 2269 putchar('('); /* ) */ 2270 without this, some vi users would have a hard time to match a pair of 2271 brackets. Although this type of bracket seems clumsy and is even 2272 harmful for some other type of vi users and Emacs users, the 2273 agreement in the KAME developers is to allow it. 2274- add the following line to the head of every KAME-derived file: 2275 /* (dollar)KAME(dollar) */ 2276 where "(dollar)" is the dollar character ($), and around "$" are tabs. 2277 (this is for C. For other language, you should use its own comment 2278 line.) 2279 Once committed to the CVS repository, this line will contain its 2280 version number (see, for example, at the top of this file). This 2281 would make it easy to report a bug. 2282- when creating a new file with the WIDE copyright, tap "make copyright.c" at 2283 the top-level, and use copyright.c as a template. KAME RCS tag will be 2284 included automatically. 2285- when editing a third-party package, keep its own coding style as 2286 much as possible, even if the style does not follow the items above. 2287- it is recommended to always wrap an expression containing 2288 bitwise operators by parentheses, especially when the expression is 2289 combined with relational operators, in order to avoid unintentional 2290 mismatch of operators. Thus, we should write 2291 if ((a & b) == 0) /* (A) */ 2292 or 2293 if (a & (b == 0)) /* (B) */ 2294 instead of 2295 if (a & b == 0) /* (C) */ 2296 even if the programmer's intention was (C), which is equivalent to 2297 (B) according to the grammar of the language C. 2298 Thus, we should write a code to test if a bit-flag is set for a 2299 given variable as follows: 2300 if ((flag & FLAG_A) == 0) /* (D) the FLAG_A is NOT set */ 2301 if ((flag & FLAG_A) != 0) /* (E) the FLAG_A is set */ 2302 Some developers in the KAME project rather prefer the following style: 2303 if (!(flag & FLAG_A)) /* (F) the FLAG_A is NOT set */ 2304 if ((flag & FLAG_A)) /* (G) the FLAG_A is set */ 2305 because it would be more intuitive in terms of the relationship 2306 between the negation operator (!) and the semantics of the 2307 condition. The KAME developers have discussed the style, and have 2308 agreed that all the styles from (D) to (G) are valid. So, when you 2309 see styles like (D) and (E) in the KAME code and feel a bit strange, 2310 please just keep them. They are intentional. 2311- When inserting a separate block just to define some intra-block 2312 variables, add the level of indentation as if the block was in a 2313 control statement such as if-else, for, or while. For example, 2314 foo () 2315 { 2316 int a; 2317 2318 { 2319 int internal_a; 2320 ... 2321 } 2322 } 2323 should be used, instead of 2324 foo () 2325 { 2326 int a; 2327 2328 { 2329 int internal_a; 2330 ... 2331 } 2332 } 2333- Do not use printf() or log() in the packet input path of the kernel code. 2334 They can make the system vulnerable to packet flooding attacks (results in 2335 /var overflow). 2336- (not a style issue) 2337 To disable a module that is mistakenly imported (by CVS), just 2338 remove the source tree in the repository. Note, however, that the 2339 removal might annoy other developers who have already checked the 2340 module out, so you should announce the removal as soon as possible. 2341 Also, be 100% sure not to remove other modules. 2342 2343When you want to contribute something to the KAME project, and if *you 2344do not mind* the agreement, it would be helpful for the project to 2345keep these rules. Note, however, that we would never intend to force 2346you to adopt our rules. We would rather regard your own style, 2347especially when you have a policy about the style. 2348 2349 23508. Policy on technology with intellectual property right restriction 2351 2352There are quite a few IETF documents/whatever which has intellectual property 2353right (IPR) restriction. KAME's stance is stated below. 2354 2355 The goal of KAME is to provide freely redistributable, BSD-licensed, 2356 implementation of Internet protocol technologies. 2357 For this purpose, we implement protocols that (1) do not need license 2358 contract with IPR holder, and (2) are royalty-free. 2359 The reason for (1) is, even if KAME contracts with the IPR holder in 2360 question, the users of KAME stack (usually implementers of some other 2361 codebase) would need to make a license contract with the IPR holder. 2362 It would damage the "freely redistributable" status of KAME codebase. 2363 2364 By doing so KAME is (implicitly) trying to advocate no-license-contract, 2365 royalty-free, release of IPRs. 2366 2367Note however, as documented in README, we do not guarantee that KAME code 2368is free of IPR infringement, you MUST check it if you are to integrate 2369KAME into your product (or whatever): 2370 READ CAREFULLY: Several countries have legal enforcement for 2371 export/import/use of cryptographic software. Check it before playing 2372 with the kit. We do not intend to be your legalese clearing house 2373 (NO WARRANTY). If you intend to include KAME stack into your product, 2374 you'll need to check if the licenses on each file fit your situations, 2375 and/or possible intellectual property right issues. 2376 2377 <end of IMPLEMENTATION> 2378