1# $FreeBSD$ 2 3# 4# This is an example that shows how to send ASCII formatted control 5# messages to a node using ngctl(8). 6# 7# What we will do here create a divert(4) tap. This simply dumps 8# out all packets diverted by some ipfw(8) divert rule to the console. 9# 10# Lines that begin with ``$'' (shell prompt) or ``+'' (ngctl prompt) 11# indicate user input 12# 13 14# First, start up ngctl in interactive mode: 15 16 $ ngctl 17 Available commands: 18 connect Connects hook <peerhook> of the node at <relpath> to <hook> 19 debug Get/set debugging verbosity level 20 help Show command summary or get more help on a specific command 21 list Show information about all nodes 22 mkpeer Create and connect a new node to the node at "path" 23 msg Send a netgraph control message to the node at "path" 24 name Assign name <name> to the node at <path> 25 read Read and execute commands from a file 26 rmhook Disconnect hook "hook" of the node at "path" 27 show Show information about the node at <path> 28 shutdown Shutdown the node at <path> 29 status Get human readable status information from the node at <path> 30 types Show information about all installed node types 31 quit Exit program 32 + 33 34# Now let's create a ng_ksocket(4) node, in the family PF_INET, 35# of type SOCK_RAW, and protocol IPPROTO_DIVERT: 36 37 + mkpeer ksocket foo inet/raw/divert 38 39# Note that ``foo'' is the hook name on the socket node, which can be 40# anything. The ``inet/raw/divert'' is the hook name on the ksocket 41# node, which tells it what kind of socket to create. 42 43# Lets give our ksocket node a global name. How about ``fred'': 44 45 + name foo fred 46 47# Note that we used ngctl's ``name'' command to do this. However, 48# the following manually constructed netgraph message would have 49# accomplished the exact same thing: 50 51 + msg foo name { name="fred" } 52 53# Here we are using the ASCII <-> binary control message conversion 54# routines. ngctl does this for us automatically when we use the 55# ``msg'' command. 56 57# Now lets bind the socket associated with the ksocket node to a port 58# supplied by the system. We do this by sending the ksocket node a 59# ``bind'' control message. Again, ngctl does the conversion of the 60# control message from ASCII to binary behind the scenes. 61 62 + msg fred: bind inet/192.168.1.1 63 64# The ksocket accepts arbitrary sockaddr structures, but also has 65# special support for the PF_LOCAL and PF_INET protocol families. 66# That is why we can specify the struct sockaddr argument to the 67# ``bind'' command as ``inet/192.168.1.1'' (since we didn't specify 68# a port number, it's assumed to be zero). We could have also 69# relied on the generic sockaddr syntax and instead said this: 70 71 + msg fred: bind { family=2 len=16 data=[ 2=192 168 1 1 ] } 72 73# This is what you would have to do for protocol families other 74# that PF_INET and PF_LOCAL, at least until special handling for 75# new ones is added. 76 77# The reason for the ``2=192'' is to skip the two byte IP port number, 78# which causes it to be set to zero, the default value for integral 79# types when parsing. Now since we didn't ask for a specific port 80# number, we need to do a ``getname'' to see what port number we got: 81 82 + msg fred: getname 83 Rec'd response "getname" (5) from "fred:": 84 Args: inet/192.168.1.1:1029 85 86# As soon as we sent the message, we got back a response. Here 87# ngctl is telling us that it received a control message with the 88# NGF_RESP (response) flag set, the response was to a prior ``getname'' 89# control message, that the originator was the node addressable 90# as ``fred:''. The message arguments field is then displayed to 91# us in its ASCII form. In this case, what we get back is a struct 92# sockaddr, and there we see that our port number is 1029. 93 94# So now let's add the ipfw divert rule for whatever packets we 95# want to see. How about anything from 192.168.1.129. 96 97 + ^Z 98 Suspended 99 $ ipfw add 100 divert 1029 ip from 192.168.1.129 to any 100 00100 divert 1029 ip from 192.168.1.129 to any 101 $ fg 102 103# Now watch what happens when we try to ping from that machine: 104 105 + 106 Rec'd data packet on hook "foo": 107 0000: 45 00 00 3c 57 00 00 00 20 01 bf ee c0 a8 01 81 E..<W... ....... 108 0010: c0 a8 01 01 08 00 49 5c 03 00 01 00 61 62 63 64 ......I\....abcd 109 0020: 65 66 67 68 69 6a 6b 6c 6d 6e 6f 70 71 72 73 74 efghijklmnopqrst 110 0030: 75 76 77 61 62 63 64 65 66 67 68 69 uvwabcdefghi 111 + 112 Rec'd data packet on hook "foo": 113 0000: 45 00 00 3c 58 00 00 00 20 01 be ee c0 a8 01 81 E..<X... ....... 114 0010: c0 a8 01 01 08 00 48 5c 03 00 02 00 61 62 63 64 ......H\....abcd 115 0020: 65 66 67 68 69 6a 6b 6c 6d 6e 6f 70 71 72 73 74 efghijklmnopqrst 116 0030: 75 76 77 61 62 63 64 65 66 67 68 69 uvwabcdefghi 117 + 118 Rec'd data packet on hook "foo": 119 0000: 45 00 00 3c 59 00 00 00 20 01 bd ee c0 a8 01 81 E..<Y... ....... 120 0010: c0 a8 01 01 08 00 47 5c 03 00 03 00 61 62 63 64 ......G\....abcd 121 0020: 65 66 67 68 69 6a 6b 6c 6d 6e 6f 70 71 72 73 74 efghijklmnopqrst 122 0030: 75 76 77 61 62 63 64 65 66 67 68 69 uvwabcdefghi 123 + 124 125# So we're seeing the output from the ksocket socket appear on the ``foo'' 126# hook of ngctl's socket node. Since the packets are getting diverted, 127# the 192.168.1.129 machine doesn't see any response from us. 128 129# Of course, any type of socket can be used, even TCP: 130 131 + mkpeer ksocket bar inet/stream/tcp 132 + msg bar connect inet/192.168.1.33:13 133 ngctl: send msg: Operation now in progress 134 + 135 Rec'd data packet on hook "foo": 136 0000: 4d 6f 6e 20 4e 6f 76 20 32 39 20 31 37 3a 34 38 Mon Nov 29 17:48 137 0010: 3a 33 37 20 31 39 39 39 0d 0a :37 1999.. 138 + 139 140# Or, UNIX domain: 141 142 + mkpeer ksocket bar local/stream/0 143 + msg bar bind local/"/tmp/bar.socket" 144 + 145 146# Here's an example of a more complicated ASCII control message argument. 147# If you look in /sys/netgraph/ng_message.h, you will see that a node 148# responds to a NGM_LISTHOOKS with a struct hooklist, which contains 149# an array of struct linkinfo: 150# 151# /* Structure used for NGM_LISTHOOKS */ 152# struct linkinfo { 153# char ourhook[NG_HOOKSIZ]; /* hook name */ 154# char peerhook[NG_HOOKSIZ]; /* peer hook */ 155# struct nodeinfo nodeinfo; 156# }; 157# 158# struct hooklist { 159# struct nodeinfo nodeinfo; /* node information */ 160# struct linkinfo link[0]; /* info about each hook */ 161# }; 162# 163# By sending a node the ``listhooks'' command using ngctl, we can see 164# this structure in ASCII form (lines wrapped for readability): 165 166 + msg bar bind local/"/tmp/bar.socket" 167 + msg bar listhooks 168 Rec'd response "listhooks" (7) from "bar": 169 Args: { nodeinfo={ type="ksocket" id=9 hooks=1 } 170 linkinfo=[ { ourhook="local/stream/0" peerhook="bar" 171 nodeinfo={ name="ngctl1327" type="socket" id=8 hooks=1 } } ] } 172 173 174