1.\" Copyright (c) 1985, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.Dd September 15, 2023 29.Dt PING 8 30.Os 31.Sh NAME 32.Nm ping 33.Nd send 34ICMP 35or 36ICMPv6 ECHO_REQUEST 37packets to network hosts 38.Sh SYNOPSIS 39.Nm 40.Op Fl 4AaDdfHnoQqRrv 41.Op Fl .\& Ns Ar chars 42.Op Fl C Ar pcp 43.Op Fl c Ar count 44.Op Fl G Ar sweepmaxsize 45.Op Fl g Ar sweepminsize 46.Op Fl h Ar sweepincrsize 47.Op Fl i Ar wait 48.Op Fl l Ar preload 49.Op Fl M Cm mask | time 50.Op Fl m Ar ttl 51.Op Fl P Ar policy 52.Op Fl p Ar pattern 53.Op Fl S Ar src_addr 54.Op Fl s Ar packetsize 55.Op Fl t Ar timeout 56.Op Fl W Ar waittime 57.Op Fl z Ar tos 58.Ar IPv4-host 59.Nm 60.Op Fl 4AaDdfHLnoQqRrv 61.Op Fl .\& Ns Ar chars 62.Op Fl C Ar pcp 63.Op Fl c Ar count 64.Op Fl I Ar iface 65.Op Fl i Ar wait 66.Op Fl l Ar preload 67.Op Fl M Cm mask | time 68.Op Fl m Ar ttl 69.Op Fl P Ar policy 70.Op Fl p Ar pattern 71.Op Fl S Ar src_addr 72.Op Fl s Ar packetsize 73.Op Fl T Ar ttl 74.Op Fl t Ar timeout 75.Op Fl W Ar waittime 76.Op Fl z Ar tos 77.Ar IPv4-mcast-group 78.Nm 79.Op Fl 6AaDdEfHNnOoquvYyZ 80.Op Fl .\& Ns Ar chars 81.Op Fl b Ar bufsiz 82.Op Fl C Ar pcp 83.Op Fl c Ar count 84.Op Fl e Ar gateway 85.Op Fl I Ar interface 86.Op Fl i Ar wait 87.Op Fl k Ar addrtype 88.Op Fl l Ar preload 89.Op Fl m Ar hoplimit 90.Op Fl P Ar policy 91.Op Fl p Ar pattern 92.Op Fl S Ar sourceaddr 93.Op Fl s Ar packetsize 94.Op Fl t Ar timeout 95.Op Fl W Ar waittime 96.Op Ar IPv6-hops ... 97.Ar IPv6-host 98.Sh DESCRIPTION 99The 100.Nm 101utility invoked with an IPv4 target 102.Ar ( IPv4-host 103or 104.Ar IPv4-mcast-group ) 105uses the 106ICMP 107.No protocol Ap s mandatory 108ECHO_REQUEST 109datagram to elicit an 110ICMP ECHO_RESPONSE 111from a host or gateway. 112ECHO_REQUEST 113datagrams 114.Pq Dq pings 115have an IP and 116ICMP 117header, followed by a 118.Dq struct timeval 119and then an arbitrary number of 120.Dq pad 121bytes used to fill out the packet. 122.Pp 123When invoked with an IPv6 target 124.Ar ( IPv6-host ) , 125it uses the 126ICMPv6 127protocol's mandatory 128ICMP6_ECHO_REQUEST 129datagram to elicit an 130ICMP6_ECHO_REPLY. 131ICMP6_ECHO_REQUEST 132datagrams have an IPv6 header and 133ICMPv6 134header formatted as documented in RFC 2463. 135.Pp 136When invoked with a hostname, the version to which the target is resolved first 137is used. 138In that case, the options and arguments used must be valid for the specific IP 139version, otherwise 140.Nm 141exits with an error. 142If the target is resolved to both IPv4 and IPv6, the specific IP version can be 143requested by 144.Fl 4 145or 146.Fl 6 147options, respectively. 148For backwards-compatibility, ICMPv6 can also be selected by invoking the binary 149as 150.Nm ping6 . 151.Ss Options common to both IPv4 and IPv6 targets 152.Bl -tag -width indent 153.It Fl .\& Ns Ar chars 154By default, for every 155ECHO_REQUEST 156sent, a period 157.Dq .\& 158is printed, while for every 159ECHO_REPLY 160received, a backspace is printed. 161This option takes an optional string argument listing characters 162that will be printed one by one in the provided order 163instead of the default period. 164.Pp 165Example usage: 166.Bd -literal -offset indent 167ping -.0123456789 freebsd.org 168.Ed 169.It Fl A 170Audible. 171Output a bell 172(ASCII 1730x07) 174character when no packet is received before the next packet 175is transmitted. 176To cater for round-trip times that are longer than the interval 177between transmissions, further missing packets cause a bell only 178if the maximum number of unreceived packets has increased. 179.It Fl a 180Audible. 181Include a bell 182(ASCII 1830x07) 184character in the output when any packet is received. 185.It Fl C Ar pcp 186Add an 802.1p Ethernet Priority Code Point when sending a packet. 1870..7 uses that specific PCP, -1 uses the interface default PCP (or none). 188.It Fl c Ar count 189Stop after sending 190(and receiving) 191.Ar count 192ECHO_RESPONSE 193packets. 194If this option is not specified, 195.Nm 196will operate until interrupted. 197.Pp 198For an IPv4 target, if this option is specified in conjunction with ping sweeps, 199each sweep will consist of 200.Ar count 201packets. 202.It Fl D 203Disable fragmentation. 204.It Fl d 205Set the 206.Dv SO_DEBUG 207option on the socket being used. 208.It Fl f 209Flood ping. 210Outputs packets as fast as they come back or one hundred times per second, 211whichever is more. 212Implies 213.Fl .\& 214to print a period for every 215ECHO_REQUEST 216sent and a backspace for every 217ECHO_REPLY 218received. 219This provides a rapid display of how many packets are being dropped. 220Only the super-user may use this option. 221.Bf -emphasis 222This can be very hard on a network and should be used with caution. 223.Ef 224.It Fl H 225Hostname output. 226Try to do a reverse DNS lookup when displaying addresses. 227This is the opposite of the 228.Fl n 229option. 230.It Fl I Ar iface 231For an IPv4 target, 232.Ar iface 233is an IP address indentifying an interface from which the packets will be sent. 234This flag applies only if the ping target is a multicast address. 235.Pp 236For an IPv6 target, 237.Ar iface 238is a name of an interface (e.g., `em0') from which the packets will be sent. 239This flag applies if the ping target is a multicast address, or 240link-local/site-local unicast address. 241.It Fl i Ar wait 242Wait 243.Ar wait 244seconds 245.Em between sending each packet . 246The default is to wait for one second between each packet. 247The wait time may be fractional, but only the super-user may specify 248values less than 1 second. 249This option is incompatible with the 250.Fl f 251option. 252.It Fl l Ar preload 253If 254.Ar preload 255is specified, 256.Nm 257sends that many packets as fast as possible before falling into its normal 258mode of behavior. 259Only the super-user may use this option. 260.It Fl m Ar ttl 261For an IPv4 target, set the IP Time To Live for outgoing packets. 262If not specified, the kernel uses the value of the 263.Va net.inet.ip.ttl 264MIB variable. 265.Pp 266For an IPv6 target, set the IPv6 hoplimit. 267.It Fl n 268Numeric output only. 269No attempt will be made to lookup symbolic names for host addresses. 270This is the opposite of 271.Fl H , 272and it is the default behavior. 273.It Fl o 274Exit successfully after receiving one reply packet. 275.It Fl P Ar policy 276.Ar policy 277specifies IPsec policy for the ping session. 278For details please refer to 279.Xr ipsec 4 280and 281.Xr ipsec_set_policy 3 . 282.It Fl p Ar pattern 283You may specify up to 16 284.Dq pad 285bytes to fill out the packet you send. 286This is useful for diagnosing data-dependent problems in a network. 287For example, 288.Dq Li \-p ff 289will cause the sent packet to be filled with all 290ones. 291.It Fl q 292Quiet output. 293Nothing is displayed except the summary lines at startup time and 294when finished. 295.It Fl S Ar src_addr 296Use the following IP address as the source address in outgoing packets. 297On hosts with more than one IP address, this option can be used to 298force the source address to be something other than the IP address 299of the interface the probe packet is sent on. 300.Pp 301For IPv4, if the IP address is not one of this machine's interface 302addresses, an error is returned and nothing is sent. 303.Pp 304For IPv6, the source address must be one of the unicast addresses of 305the sending node, and must be numeric. 306.It Fl s Ar packetsize 307Specify the number of data bytes to be sent. 308The default is 56, which translates into 64 309ICMP 310data bytes when combined 311with the 8 bytes of 312ICMP 313header data. 314.Pp 315For IPv4, only the super-user may specify values more than default. 316This option cannot be used with ping sweeps. 317.Pp 318For IPv6, you may need to specify 319.Fl b 320as well to extend socket buffer size. 321.It Fl t Ar timeout 322Specify a timeout, in seconds, before ping exits regardless of how 323many packets have been received. 324.It Fl v 325Verbose output. 326ICMP 327packets other than 328ECHO_RESPONSE 329that are received are listed. 330.It Fl W Ar waittime 331Time in milliseconds to wait for a reply for each packet sent. 332If a reply arrives later, the packet is not printed as replied, but 333considered as replied when calculating statistics. 334.El 335.Ss Options only for IPv4 targets 336.Bl -tag -width indent 337.It Fl 4 338Use IPv4 regardless of how the target is resolved. 339.It Fl G Ar sweepmaxsize 340Specify the maximum size of 341ICMP 342payload when sending sweeping pings. 343This option is required for ping sweeps. 344.It Fl g Ar sweepminsize 345Specify the size of 346ICMP 347payload to start with when sending sweeping pings. 348The default value is 0. 349.It Fl h Ar sweepincrsize 350Specify the number of bytes to increment the size of 351ICMP 352payload after 353each sweep when sending sweeping pings. 354The default value is 1. 355.It Fl L 356Suppress loopback of multicast packets. 357This flag only applies if the ping destination is a multicast address. 358.It Fl M Cm mask | time 359Use 360.Dv ICMP_MASKREQ 361or 362.Dv ICMP_TSTAMP 363instead of 364.Dv ICMP_ECHO . 365For 366.Cm mask , 367print the netmask of the remote machine. 368Set the 369.Va net.inet.icmp.maskrepl 370MIB variable to enable 371.Dv ICMP_MASKREPLY 372and 373.Va net.inet.icmp.maskfake 374if you want to override the netmask in the response. 375For 376.Cm time , 377print the origination, reception and transmission timestamps. 378Set the 379.Va net.inet.icmp.tstamprepl 380MIB variable to enable or disable 381.Dv ICMP_TSTAMPREPLY . 382.It Fl Q 383Somewhat quiet output. 384.No Don Ap t 385display ICMP error messages that are in response to our query messages. 386Originally, the 387.Fl v 388flag was required to display such errors, but 389.Fl v 390displays all ICMP error messages. 391On a busy machine, this output can be overbearing. 392Without the 393.Fl Q 394flag, 395.Nm 396prints out any ICMP error messages caused by its own ECHO_REQUEST 397messages. 398.It Fl R 399Record route. 400Includes the 401RECORD_ROUTE 402option in the 403ECHO_REQUEST 404packet and displays 405the route buffer on returned packets. 406Note that the IP header is only large enough for nine such routes; 407the 408.Xr traceroute 8 409command is usually better at determining the route packets take to a 410particular destination. 411If more routes come back than should, such as due to an illegal spoofed 412packet, ping will print the route list and then truncate it at the correct 413spot. 414Many hosts ignore or discard the 415RECORD_ROUTE 416option. 417.It Fl r 418Bypass the normal routing tables and send directly to a host on an attached 419network. 420If the host is not on a directly-attached network, an error is returned. 421This option can be used to ping a local host through an interface 422that has no route through it 423(e.g., after the interface was dropped by 424.Xr routed 8 ) . 425.It Fl T Ar ttl 426Set the IP Time To Live for multicasted packets. 427This flag only applies if the ping destination is a multicast address. 428.It Fl z Ar tos 429Use the specified type of service. 430.It Ar IPv4-host 431hostname or IPv4 address of the final destination node. 432.It Ar IPv4-mcast-group 433IPv4 multicast address of the final destination nodes. 434.El 435.Ss Options only for IPv6 targets 436.Bl -tag -width indent 437.It Fl 6 438Use IPv6 regardless of how the target is resolved. 439.It Fl b Ar bufsiz 440Set socket buffer size. 441.It Fl e Ar gateway 442Specifies to use 443.Ar gateway 444as the next hop to the destination. 445The gateway must be a neighbor of the sending node. 446.It Fl k Ar addrtype 447Generate ICMPv6 Node Information Node Addresses query, rather than echo-request. 448.Ar addrtype 449must be a string constructed of the following characters. 450.Bl -tag -width Ds -compact 451.It Ic a 452requests unicast addresses from all of the responder's interfaces. 453If the character is omitted, 454only those addresses which belong to the interface which has the 455responder's address are requests. 456.It Ic c 457requests responder's IPv4-compatible and IPv4-mapped addresses. 458.It Ic g 459requests responder's global-scope addresses. 460.It Ic s 461requests responder's site-local addresses. 462.It Ic l 463requests responder's link-local addresses. 464.It Ic A 465requests responder's anycast addresses. 466Without this character, the responder will return unicast addresses only. 467With this character, the responder will return anycast addresses only. 468Note that the specification does not specify how to get responder's 469anycast addresses. 470This is an experimental option. 471.El 472.It Fl N 473Probe node information multicast group address 474.Pq Li ff02::2:ffxx:xxxx . 475.Ar host 476must be string hostname of the target 477(must not be a numeric IPv6 address). 478Node information multicast group will be computed based on given 479.Ar host , 480and will be used as the final destination. 481Since node information multicast group is a link-local multicast group, 482outgoing interface needs to be specified by 483.Fl I 484option. 485.Pp 486When specified twice, the address 487.Pq Li ff02::2:xxxx:xxxx 488is used instead. 489The former is in RFC 4620, the latter is in an old Internet Draft 490draft-ietf-ipngwg-icmp-name-lookup. 491Note that KAME-derived implementations including 492.Fx 493use the latter. 494.It Fl O 495Generate ICMPv6 Node Information supported query types query, 496rather than echo-request. 497.Fl s 498has no effect if 499.Fl O 500is specified. 501.It Fl u 502By default, 503.Nm 504asks the kernel to fragment packets to fit into the minimum IPv6 MTU. 505The 506.Fl u 507option 508will suppress the behavior in the following two levels: 509when the option is specified once, the behavior will be disabled for 510unicast packets. 511When the option is more than once, it will be disabled for both 512unicast and multicast packets. 513.It Fl Y 514Same as 515.Fl y , 516but with old packet format based on 03 draft. 517This option is present for backward compatibility. 518.Fl s 519has no effect if 520.Fl y 521is specified. 522.It Fl y 523Generate ICMPv6 Node Information DNS Name query, rather than echo-request. 524.Fl s 525has no effect if 526.Fl y 527is specified. 528.It Ar IPv6-hops 529IPv6 addresses for intermediate nodes, 530which will be put into type 0 routing header. 531.It Ar IPv6-host 532IPv6 address of the final destination node. 533.El 534.Ss Experimental options only for IPv6 target 535.Bl -tag -width indent 536.It Fl E 537Enables transport-mode IPsec encapsulated security payload. 538.It Fl Z 539Enables transport-mode IPsec authentication header. 540.El 541.Pp 542When using 543.Nm 544for fault isolation, it should first be run on the local host, to verify 545that the local network interface is up and running. 546Then, hosts and gateways further and further away should be 547.Dq pinged . 548Round-trip times and packet loss statistics are computed. 549If duplicate packets are received, they are not included in the packet 550loss calculation, although the round trip time of these packets is used 551in calculating the round-trip time statistics. 552When the specified number of packets have been sent 553(and received) 554or if the program is terminated with a 555.Dv SIGINT , 556a brief summary is displayed, showing the number of packets sent and 557received, and the minimum, mean, maximum, and standard deviation of 558the round-trip times. 559.Pp 560If 561.Nm 562receives a 563.Dv SIGINFO 564(see the 565.Cm status 566argument for 567.Xr stty 1 ) 568signal, the current number of packets sent and received, and the 569minimum, mean, maximum, and standard deviation of the round-trip times 570will be written to the standard output. 571.Pp 572This program is intended for use in network testing, measurement and 573management. 574Because of the load it can impose on the network, it is unwise to use 575.Nm 576during normal operations or from automated scripts. 577.Sh ICMP PACKET DETAILS 578An IP header without options is 20 bytes. 579An 580ICMP 581ECHO_REQUEST 582packet contains an additional 8 bytes worth of 583ICMP 584header followed by an arbitrary amount of data. 585When a 586.Ar packetsize 587is given, this indicated the size of this extra piece of data 588(the default is 56). 589Thus the amount of data received inside of an IP packet of type 590ICMP 591ECHO_REPLY 592will always be 8 bytes more than the requested data space 593(the 594ICMP 595header). 596.Pp 597If the data space is at least eight bytes large, 598.Nm 599uses the first eight bytes of this space to include a timestamp which 600it uses in the computation of round trip times. 601If less than eight bytes of pad are specified, no round trip times are 602given. 603.Sh DUPLICATE AND DAMAGED PACKETS 604The 605.Nm 606utility will report duplicate and damaged packets. 607Duplicate packets should never occur when pinging a unicast address, 608and seem to be caused by 609inappropriate link-level retransmissions. 610Duplicates may occur in many situations and are rarely 611(if ever) 612a good sign, although the presence of low levels of duplicates may not 613always be cause for alarm. 614Duplicates are expected when pinging a broadcast or multicast address, 615since they are not really duplicates but replies from different hosts 616to the same request. 617.Pp 618Damaged packets are obviously serious cause for alarm and often 619indicate broken hardware somewhere in the 620.Nm 621packet's path (in the network or in the hosts). 622.Sh TRYING DIFFERENT DATA PATTERNS 623The 624(inter)network 625layer should never treat packets differently depending on the data 626contained in the data portion. 627Unfortunately, data-dependent problems have been known to sneak into 628networks and remain undetected for long periods of time. 629In many cases the particular pattern that will have problems is something 630that does not have sufficient 631.Dq transitions , 632such as all ones or all zeros, or a pattern right at the edge, such as 633almost all zeros. 634It is not 635necessarily enough to specify a data pattern of all zeros (for example) 636on the command line because the pattern that is of interest is 637at the data link level, and the relationship between what you type and 638what the controllers transmit can be complicated. 639.Pp 640This means that if you have a data-dependent problem you will probably 641have to do a lot of testing to find it. 642If you are lucky, you may manage to find a file that either 643cannot 644be sent across your network or that takes much longer to transfer than 645other similar length files. 646You can then examine this file for repeated patterns that you can test 647using the 648.Fl p 649option of 650.Nm . 651.Sh IPv4 TTL DETAILS 652The 653TTL 654value of an IP packet represents the maximum number of IP routers 655that the packet can go through before being thrown away. 656In current practice you can expect each router in the Internet to decrement 657the 658TTL 659field by exactly one. 660.Pp 661The 662TCP/IP 663specification recommends setting the 664TTL 665field for 666IP 667packets to 64. 668.Pp 669The maximum possible value of this field is 255, and some 670.Ux 671systems set 672the 673TTL 674field of 675ICMP ECHO_REQUEST 676packets to 255. 677This is why you will find you can 678.Dq ping 679some hosts, but not reach them with 680.Xr telnet 1 681or 682.Xr ftp 1 . 683.Pp 684In normal operation 685.Nm 686prints the ttl value from the packet it receives. 687When a remote system receives a ping packet, it can do one of three things 688with the 689TTL 690field in its response: 691.Bl -bullet 692.It 693Not change it; this is what 694.Bx 695systems did before the 696.Bx 4.3 tahoe 697release. 698In this case the 699TTL 700value in the received packet will be 255 minus the 701number of routers in the round-trip path. 702.It 703Set it to 64; this is what current 704.Fx 705systems do. 706In this case the 707TTL 708value in the received packet will be 64 minus the 709number of routers in the path 710.Em from 711the remote system 712.Em to 713the 714.Nm Ns Em ing 715host. 716.It 717Set it to some other value. 718Some machines use the same value for 719ICMP 720packets that they use for 721TCP 722packets, for example either 30 or 60. 723Others may use completely wild values. 724.El 725.Sh EXIT STATUS 726The 727.Nm 728utility exits with one of the following values: 729.Bl -tag -width indent 730.It 0 731At least one response was heard from the specified 732.Ar host . 733.It 2 734The transmission was successful but no responses were received. 735.It any other value 736An error occurred. 737.El 738.Sh EXAMPLES 739The following will send ICMPv6 echo request to 740.Li dst.example.com . 741.Bd -literal -offset indent 742ping -6 -n dst.example.com 743.Ed 744.Pp 745The following will probe hostnames for all nodes on the network link attached to 746.Li wi0 747interface. 748The address 749.Li ff02::1 750is named the link-local all-node multicast address, and the packet would 751reach every node on the network link. 752.Bd -literal -offset indent 753ping -6 -y ff02::1%wi0 754.Ed 755.Pp 756The following will probe addresses assigned to the destination node, 757.Li dst.example.com . 758.Bd -literal -offset indent 759ping -6 -k agl dst.example.com 760.Ed 761.Sh SEE ALSO 762.Xr netstat 1 , 763.Xr icmp 4 , 764.Xr icmp6 4 , 765.Xr inet6 4 , 766.Xr ip6 4 , 767.Xr ifconfig 8 , 768.Xr routed 8 , 769.Xr traceroute 8 , 770.Xr traceroute6 8 771.Rs 772.%A A. Conta 773.%A S. Deering 774.%T "Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification" 775.%N RFC 2463 776.%D December 1998 777.Re 778.Rs 779.%A Matt Crawford 780.%T "IPv6 Node Information Queries" 781.%N draft-ietf-ipngwg-icmp-name-lookups-09.txt 782.%D May 2002 783.%O work in progress material 784.Re 785.Sh HISTORY 786The 787.Nm 788utility appeared in 789.Bx 4.3 . 790The 791.Nm ping6 792utility with IPv6 support first appeared in the WIDE Hydrangea IPv6 793protocol stack kit. 794.Pp 795IPv6 and IPsec support based on the KAME Project 796.Pq Pa https://www.kame.net/ 797stack was initially integrated into 798.Fx 4.0 . 799.Pp 800The 801.Nm ping6 802utility was merged to 803.Nm 804in Google Summer of Code 2019. 805.Sh AUTHORS 806The original 807.Nm 808utility was written by 809.An Mike Muuss 810while at the US Army Ballistics 811Research Laboratory. 812.Sh BUGS 813Many Hosts and Gateways ignore the IPv4 814RECORD_ROUTE 815option. 816.Pp 817The maximum IP header length is too small for options like 818RECORD_ROUTE 819to be completely useful. 820.No There Ap s 821not much that can be done about this, however. 822.Pp 823Flood pinging is not recommended in general, and flood pinging the 824broadcast address should only be done under very controlled conditions. 825.Pp 826The 827.Fl v 828option is not worth much on busy hosts. 829