traceroute

SYNOPSIS

       traceroute [-46dFITUnrAV] [-f first_ttl] [-g gate,...]
               [-i device] [-m max_ttl] [-p port] [-s src_addr]
               [-q nqueries] [-N squeries] [-t tos]
               [-l flow_label] [-w waittime] [-z sendwait]
               host [packetlen]
       traceroute6  [options]
       tracert  [options]
       tcptraceroute  [options]

DESCRIPTION

       traceroute  tracks the route packets take across an IP network on their
       way to a given host. It utilizes the IP protocol's time to  live  (TTL)
       field  and  attempts to elicit an ICMP TIME_EXCEEDED response from each
       gateway along the path to the host.

       traceroute6 equivalents to traceroute -6
       tracert equivalents to traceroute -I
       tcptraceroute equivalents to traceroute -T -p 80

OPTIONS

       The only required parameter is the name or IP address of  the  destina-
       tion  host.  This  paremeter can be followed by the size of the probing
       packet sent to that host (40 by  default).  Varying  the  size  of  the
       packet  in  conjunction  with  the  -F  parameter can be used to obtain
       information about the MTU of individual network hops. (The size parame-
       ter is useless for TCP probes).

       Additional options are:

       --help Print help info and exit.

       -4, -6 Explicitly  force IPv4 or IPv6 traceouting. By default, the pro-
              gram will try to resolve the name given, and choose  the  appro-
              priate  protocol automatically. If resolving a host name returns
              both IPv4 and IPv6 addresses, traceroute will use IPv4.

       -I     Use ICMP ECHO for probes

       -T     Use TCP SYN for probes

       -U     Use UDP datagrams for probes (it is default). Only UDP method is
              allowed for unprivileged users.

       -d     Enable  socket  level  debugging (when the Linux kernel supports
              it)

       -F     Set the "Don't Fragment" bit. This  tells  intermediate  routers
              not  to  fragment  the  packet when they find it's too big for a
              network hop's MTU.

       -f first_ttl
              Specifies  the  maximum  number of hops (max time-to-live value)
              traceroute will probe. The default is 30.

       -N squeries
              Specifies the number of probe packets sent  out  simultaneously.
              Sending several probes concurrently can speed up traceroute con-
              siderably. The default value is 15.
              Note that some routers and hosts can use ICMP  rate  throttling.
              In such a situation specifying too large number can lead to loss
              of some responses.

       -n     Do not try to map IP addresses to  host  names  when  displaying
              them.

       -p port
              For  UDP tracing, specifies the destination port base traceroute
              will use (the destination port number  will  be  incremented  by
              each probe).
              For  ICMP  tracing,  specifies  the  initial icmp sequence value
              (incremented by each probe too).
              For TCP specifies just the (constant) destination port  to  con-
              nect.

       -t tos For  IPv4,  set  the Type of Service (TOS) and Precedence value.
              Useful values are 16 (low delay) and 8 (high  throughput).  Note
              that in order to use some TOS precendence values, you have to be
              super user.
              For IPv6, set the Traffic Control value.

       -w waittime
              Set the time (in seconds) to wait for  a  response  to  a  probe
              (default 5.0 sec).

       -q nqueries
              Sets the number of probe packets per hop. The default is 3.

       -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.

       -s source_addr
              Chooses an alternative source address. Note that you must select
              the address of one of the interfaces.  By default,  the  address
              of the outgoing interface is used.

       -z sendwait
              Minimal  time interval between probes (default 0).  If the value
              is more than 10, then it specifies  a  number  in  milliseconds,
              else it is a number of seconds (float point values allowed too).
              Useful when some routers use rate-limit for icmp messages.

       responding system will be printed.  If there is no  response  within  a
       5.0 (default) seconds, a "*" is printed for that probe.

       We  don't want the destination host to process the UDP probe packets so
       the destination port is set to an unlikely value  (you  can  change  it
       with  the -p flag). There is no such problem for ICMP or TCP tracerout-
       ing (for TCP we close sessions immediately after connect).

       After the time some additional annotation can be printed: !H, !N, or !P
       (host,  network  or protocol unreachable), !S (source route failed), !F
       (fragmentation needed), !X (communication administratively prohibited),
       !V  (host  precedence  violation), !C (precedence cutoff in effect), or
       !<num> (ICMP unreachable code <num>).  If almost all the probes  result
       in some kind of unreachable, traceroute will give up and exit.

SEE ALSO

       ping(8), ping6(8), tracepath(8), netstat(8).

Fedora Project 11 October 2006 TRACEROUTE(8)