Date: Wed, 27 Jun 2012 07:41:21 +0000 (UTC) From: Joel Dahl <joel@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r237635 - head/contrib/traceroute Message-ID: <201206270741.q5R7fL9R090350@svn.freebsd.org>
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Author: joel (doc committer) Date: Wed Jun 27 07:41:21 2012 New Revision: 237635 URL: http://svn.freebsd.org/changeset/base/237635 Log: mdocify and update the traceroute(8) manual page. Reviewed by: brueffer No objection: ru, uqs Modified: head/contrib/traceroute/traceroute.8 Modified: head/contrib/traceroute/traceroute.8 ============================================================================== --- head/contrib/traceroute/traceroute.8 Wed Jun 27 06:41:14 2012 (r237634) +++ head/contrib/traceroute/traceroute.8 Wed Jun 27 07:41:21 2012 (r237635) @@ -16,113 +16,64 @@ .\" $Id: traceroute.8,v 1.19 2000/09/21 08:44:19 leres Exp $ .\" $FreeBSD$ .\" -.TH TRACEROUTE 8 "19 February 2008" -.UC 6 -.SH NAME -traceroute \- print the route packets take to network host -.SH SYNOPSIS -.na -.B traceroute -[ -.B \-adDeFISnrvx -] [ -.B \-f -.I first_ttl -] [ -.B \-g -.I gateway -] -.br -.ti +8 -[ -.B \-i -.I iface -] [ -.B \-M -.I first_ttl -] -.br -.ti +8 -[ -.B \-m -.I max_ttl -] [ -.B \-P -.I proto -] [ -.B \-p -.I port -] -.br -.ti +8 -[ -.B \-q -.I nqueries -] [ -.B \-s -.I src_addr -] [ -.B \-t -.I tos -] -.br -.ti +8 -[ -.B \-w -.I waittime -] [ -.B \-A -.I as_server -] [ -.B \-z -.I pausemsecs -] -.br -.ti +8 -.I host -[ -.I packetlen -] -.ad -.SH DESCRIPTION +.Dd June 19, 2012 +.Dt TRACEROUTE 8 +.Os +.Sh NAME +.Nm traceroute +.Nd "print the route packets take to network host" +.Sh SYNOPSIS +.Nm +.Bk -words +.Op Fl adDeFISnrvx +.Op Fl f Ar first_ttl +.Op Fl g Ar gateway +.Op Fl M Ar first_ttl +.Op Fl m Ar max_ttl +.Op Fl P Ar proto +.Op Fl p Ar port +.Op Fl q Ar nqueries +.Op Fl s Ar src_addr +.Op Fl t Ar tos +.Op Fl w Ar waittime +.Op Fl A Ar as_server +.Op Fl z Ar pausemsecs +.Ar host +.Op Ar packetlen +.Ek +.Sh DESCRIPTION The Internet is a large and complex aggregation of network hardware, connected together by gateways. Tracking the route one's packets follow (or finding the miscreant gateway that's discarding your packets) can be difficult. -.I Traceroute +.Nm utilizes the IP protocol `time to live' field and attempts to elicit an ICMP TIME_EXCEEDED response from each gateway along the path to some host. -.PP +.Pp The only mandatory parameter is the destination host name or IP number. The default probe datagram length is 40 bytes, but this may be increased by specifying a packet length (in bytes) after the destination host name. -.PP +.Pp Other options are: -.TP -.B \-a +.Bl -tag -width Ds +.It Fl a Turn on AS# lookups for each hop encountered. -.TP -.B -A +.It Fl A Ar as_server Turn on AS# lookups and use the given server instead of the default. -.TP -.B \-e +.It Fl e Firewall evasion mode. Use fixed destination ports for UDP and TCP probes. The destination port does NOT increment with each packet sent. -.TP -.B \-f +.It Fl f Ar first_ttl Set the initial time-to-live used in the first outgoing probe packet. -.TP -.B \-F +.It Fl F Set the "don't fragment" bit. -.TP -.B \-d +.It Fl d Enable socket level debugging. -.TP -.B \-D +.It Fl D When an ICMP response to our probe datagram is received, print the differences between the transmitted packet and the packet quoted by the ICMP response. @@ -133,74 +84,66 @@ Bytes that are unchanged in the quoted p Note, the IP checksum and the TTL of the quoted packet are not expected to match. By default, only one probe per hop is sent with this option. -.TP -.B \-g +.It Fl g Ar gateway Specify a loose source route gateway (8 maximum). -.TP -.B \-i +.It Fl i Ar iface Specify a network interface to obtain the source IP address for outgoing probe packets. This is normally only useful on a multi-homed host. (See the -.B \-s +.Fl s flag for another way to do this.) -.TP -.B \-I +.It Fl I Use ICMP ECHO instead of UDP datagrams. (A synonym for "-P icmp"). -.TP -.B \-M +.It Fl M Ar first_ttl Set the initial time-to-live value used in outgoing probe packets. The default is 1, i.e., start with the first hop. -.TP -.B \-m +.It Fl m Ar max_ttl Set the max time-to-live (max number of hops) used in outgoing probe -packets. The default is -.I net.inet.ip.ttl -hops (the same default used for TCP +packets. The default is the value of the +.Va net.inet.ip.ttl +.Xr sysctl 8 +(the same default used for TCP connections). -.TP -.B \-n +.It Fl n Print hop addresses numerically rather than symbolically and numerically (saves a nameserver address-to-name lookup for each gateway found on the path). -.TP -.B \-P +.It Fl P Ar proto Send packets of specified IP protocol. The currently supported protocols are: UDP, TCP, GRE and ICMP. Other protocols may also be specified (either by name or by number), though -.I traceroute +.Nm does not implement any special knowledge of their packet formats. This option is useful for determining which router along a path may be blocking packets based on IP protocol number. But see BUGS below. -.TP -.B \-p +.It Fl p Ar port Protocol specific. For UDP and TCP, sets -the base port number used in probes (default is 33434). +the base +.Ar port +number used in probes (default is 33434). Traceroute hopes that nothing is listening on UDP ports -.I base +.Em base to -.I base + nhops * nprobes - 1 +.Em base + nhops * nprobes - 1 at the destination host (so an ICMP PORT_UNREACHABLE message will be returned to terminate the route tracing). If something is listening on a port in the default range, this option can be used to pick an unused port range. -.TP -.B \-q +.It Fl q Ar nqueries Set the number of probes per hop (default is 3, unless -.B -D +.Fl D is specified, when it is 1). -.TP -.B \-r +.It Fl r Bypass the normal routing tables and send directly to a host on an attached network. If the host is not on a directly-attached network, an error is returned. This option can be used to ping a local host through an interface that has no route through it (e.g., after the interface was dropped by -.IR routed (8C)). -.TP -.B \-s +.Xr routed 8 . +.It Fl s Ar src_addr Use the following IP address (which usually is given as an IP number, not a hostname) as the source address in outgoing probe packets. On multi-homed hosts (those with more than one IP @@ -209,15 +152,13 @@ force the source address to be something of the interface the probe packet is sent on. If the IP address is not one of this machine's interface addresses, an error is returned and nothing is sent. (See the -.B \-i +.Fl i flag for another way to do this.) -.TP -.B \-S +.It Fl S Print a summary of how many probes were not answered for each hop. -.TP -.B \-t +.It Fl t Ar tos Set the -.I type-of-service +.Em type-of-service in probe packets to the following value (default zero). The value must be a decimal integer in the range 0 to 255. This option can be used to see if different types-of-service result in different paths. (If you @@ -226,72 +167,69 @@ services like telnet and ftp don't let y Not all values of TOS are legal or meaningful \- see the IP spec for definitions. Useful values are probably -.RB ` -t -.IR 16 ' +.Fl t Ar 16 (low delay) and -.RB ` -t -.IR 8 ' +.Fl t Ar 8 (high throughput). -.TP -.B \-v -Verbose output. Received ICMP packets other than TIME_EXCEEDED and -UNREACHABLEs are listed. -.TP -.B \-w +.It Fl v +Verbose output. Received ICMP packets other than +.Dv TIME_EXCEEDED +and +.Dv UNREACHABLE Ns s +are listed. +.It Fl w Ar waittime Set the time (in seconds) to wait for a response to a probe (default 5 sec.). -.TP -.B \-x +.It Fl x Toggle ip checksums. Normally, this prevents traceroute from calculating ip checksums. In some cases, the operating system can overwrite parts of the outgoing packet but not recalculate the checksum (so in some cases the default is to not calculate checksums and using -.B \-x +.Fl x causes them to be calculated). Note that checksums are usually required for the last hop when using ICMP ECHO probes -.RB ( \-I ). +.Pq Fl I . So they are always calculated when using ICMP. -.TP -.B \-z +.It Fl z Ar pausemsecs Set the time (in milliseconds) to pause between probes (default 0). Some systems such as Solaris and routers such as Ciscos rate limit icmp messages. A good value to use with this this is 500 (e.g. 1/2 second). -.PP +.El +.Pp This program attempts to trace the route an IP packet would follow to some internet host by launching UDP probe packets with a small ttl (time to live) then listening for an ICMP "time exceeded" reply from a gateway. We start our probes with a ttl of one and increase by one until we get an ICMP "port unreachable" (which means we got to "host") or hit a max (which -defaults to -.I net.inet.ip.ttl -hops & can be changed with the -.B \-m +defaults to the amount of hops specified by the +.Va net.inet.ip.ttl +.Xr sysctl 8 +and can be changed with the +.Fl m flag). Three probes (change with -.B \-q +.Fl q flag) are sent at each ttl setting and a line is printed showing the ttl, address of the gateway and round trip time of each probe. If the probe answers come from different gateways, the address of each responding system will be printed. If there is no response within a 5 sec. timeout interval (changed with the -.B \-w +.Fl w flag), a "*" is printed for that probe. -.PP +.Pp We don't want the destination host to process the UDP probe packets so the destination port is set to an unlikely value (if some clod on the destination is using that value, it can be changed with the -.B \-p +.Fl p flag). -.PP +.Pp A sample use and output might be: - -.RS -.nf -[yak 71]% traceroute nis.nsf.net. +.Bd -literal -offset 4n +% traceroute nis.nsf.net. traceroute to nis.nsf.net (35.1.1.48), 64 hops max, 38 byte packet 1 helios.ee.lbl.gov (128.3.112.1) 19 ms 19 ms 0 ms 2 lilac-dmc.Berkeley.EDU (128.32.216.1) 39 ms 39 ms 19 ms @@ -304,21 +242,18 @@ traceroute to nis.nsf.net (35.1.1.48), 6 9 129.140.71.6 (129.140.71.6) 139 ms 239 ms 319 ms 10 129.140.81.7 (129.140.81.7) 220 ms 199 ms 199 ms 11 nic.merit.edu (35.1.1.48) 239 ms 239 ms 239 ms -.fi -.RE - +.Ed +.Pp Note that lines 2 & 3 are the same. This is due to a buggy kernel on the 2nd hop system \- lilac-dmc.Berkeley.EDU \- that forwards packets with a zero ttl (a bug in the distributed version of 4.3BSD). Note that you have to guess what path the packets are taking cross-country since the NSFNet (129.140) doesn't supply address-to-name translations for its NSSes. -.PP +.Pp A more interesting example is: - -.RS -.nf -[yak 72]% traceroute allspice.lcs.mit.edu. +.Bd -literal -offset 4n +% traceroute allspice.lcs.mit.edu. traceroute to allspice.lcs.mit.edu (18.26.0.115), 64 hops max 1 helios.ee.lbl.gov (128.3.112.1) 0 ms 0 ms 0 ms 2 lilac-dmc.Berkeley.EDU (128.32.216.1) 19 ms 19 ms 19 ms @@ -338,15 +273,14 @@ traceroute to allspice.lcs.mit.edu (18.2 16 * * * 17 * * * 18 ALLSPICE.LCS.MIT.EDU (18.26.0.115) 339 ms 279 ms 279 ms -.fi -.RE - +.Ed +.Pp Note that the gateways 12, 14, 15, 16 & 17 hops away either don't send ICMP "time exceeded" messages or send them with a ttl too small to reach us. 14 \- 17 are running the MIT C Gateway code that doesn't send "time exceeded"s. God only knows what's going on with 12. -.PP +.Pp The silent gateway 12 in the above may be the result of a bug in the 4.[23]BSD network code (and its derivatives): 4.x (x <= 3) sends an unreachable message using whatever ttl remains in the @@ -354,9 +288,7 @@ original datagram. Since, for gateways, zero, the ICMP "time exceeded" is guaranteed to not make it back to us. The behavior of this bug is slightly more interesting when it appears on the destination system: - -.RS -.nf +.Bd -literal -offset 4n 1 helios.ee.lbl.gov (128.3.112.1) 0 ms 0 ms 0 ms 2 lilac-dmc.Berkeley.EDU (128.32.216.1) 39 ms 19 ms 39 ms 3 lilac-dmc.Berkeley.EDU (128.32.216.1) 19 ms 39 ms 19 ms @@ -370,9 +302,8 @@ when it appears on the destination syste 11 * * * 12 * * * 13 rip.Berkeley.EDU (128.32.131.22) 59 ms ! 39 ms ! 39 ms ! -.fi -.RE - +.Ed +.Pp Notice that there are 12 "gateways" (13 is the final destination) and exactly the last half of them are "missing". What's really happening is that rip (a Sun-3 running Sun OS3.5) @@ -383,77 +314,82 @@ ICMP's) until we probe with a ttl that's length. I.e., rip is really only 7 hops away. A reply that returns with a ttl of 1 is a clue this problem exists. Traceroute prints a "!" after the time if the ttl is <= 1. -Since vendors ship a lot of obsolete (DEC's Ultrix, Sun 3.x) or -non-standard (HPUX) software, expect to see this problem +Since vendors ship a lot of obsolete +.Pf ( Tn DEC Ns \'s +Ultrix, Sun 3.x) or +non-standard +.Pq Tn HP-UX +software, expect to see this problem frequently and/or take care picking the target host of your probes. - -Other possible annotations after the time are -.BR !H , -.BR !N , -or -.B !P -(host, network or protocol unreachable), -.B !S -(source route failed), -.B !F\-<pmtu> -(fragmentation needed \- the RFC1191 Path MTU Discovery value is displayed), -.B !U -or -.B !W -(destination network/host unknown), -.B !I -(source host is isolated), -.B !A -(communication with destination network administratively prohibited), -.B !Z -(communication with destination host administratively prohibited), -.B !Q -(for this ToS the destination network is unreachable), -.B !T -(for this ToS the destination host is unreachable), -.B !X -(communication administratively prohibited), -.B !V -(host precedence violation), -.B !C -(precedence cutoff in effect), or -.B !<num> -(ICMP unreachable code <num>). +.Pp +Other possible annotations after the time are: +.Bl -hang -offset indent -width 12n +.It Sy !H +Host unreachable. +.It Sy !N +Network unreachable. +.It Sy !P +Protocol unreachable. +.It Sy !S +Source route failed. +.It Sy !F\-<pmtu> +Fragmentation needed. +The RFC1191 Path MTU Discovery value is displayed. +.It Sy !U +Destination network unknown. +.It Sy !W +Destination host unknown. +.It Sy !I +Source host is isolated. +.It Sy !A +Communication with destination network administratively prohibited. +.It Sy !Z +Communication with destination host administratively prohibited. +.It Sy !Q +For this ToS the destination network is unreachable. +.It Sy !T +For this ToS the destination host is unreachable. +.It Sy !X +Communication administratively prohibited. +.It Sy !V +Host precedence violation. +.It Sy !C +Precedence cutoff in effect. +.It Sy !<num> +ICMP unreachable code <num>. +.El +.Pp These are defined by RFC1812 (which supersedes RFC1716). -If almost all the probes result in some kind of unreachable, traceroute +If almost all the probes result in some kind of unreachable, +.Nm will give up and exit. -.PP +.Pp This program is intended for use in network testing, measurement and management. It should be used primarily for manual fault isolation. Because of the load it could impose on the network, it is unwise to use -.I traceroute +.Nm during normal operations or from automated scripts. -.SH SEE ALSO -pathchar(8), netstat(1), ping(8) -.SH AUTHOR +.Sh SEE ALSO +.Xr netstat 1 , +.Xr ping 8 , +.Xr ping6 8 , +.Xr traceroute6 8 . +.Sh AUTHORS Implemented by Van Jacobson from a suggestion by Steve Deering. Debugged by a cast of thousands with particularly cogent suggestions or fixes from C. Philip Wood, Tim Seaver and Ken Adelman. -.LP -The current version is available via anonymous ftp: -.LP -.RS -.I ftp://ftp.ee.lbl.gov/traceroute.tar.gz -.RE -.SH BUGS +.Sh BUGS When using protocols other than UDP, functionality is reduced. In particular, the last packet will often appear to be lost, because even though it reaches the destination host, there's no way to know that because no ICMP message is sent back. In the TCP case, -.I traceroute +.Nm should listen for a RST from the destination host (or an intermediate router that's filtering packets), but this is not implemented yet. -.PP -Please send bug reports to traceroute@ee.lbl.gov. -.PP +.Pp The AS number capability reports information that may sometimes be inaccurate due to discrepancies between the contents of the routing database server and the current state of the Internet.
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