traceroute - print route packets take to network host
traceroute [-adnruvAMOQ] [-w wait_time] [-S start_ttl] [-m max_ttl] [-p port] [-q nqueries] [-g gateway] [-t tos] [-s src_addr] [-g router] host [packet size]
Traceroute attempts to trace the route an ip packet follows to some internet host. We find out intermediate hops by launching probe packets with a small ttl (time to live) and then listening for an icmp reply of "time exceeded" from an intermediate router. We start our probes with a ttl of one and then increment by one until we get an icmp "port unreachable", which means we got to "host", or hit the max ttl, which defaults to 30 hops and can be changed with the -m flag. Three probes are sent to each intermediate host (change with -q flag) and a line showing the ttl, network address, and round trip time of each probe is printed. If there is no response within the timeout period (defaults to 5 seconds, changed with -w flag), a "*" is printed for that "hop".
The only mandatory argument is "HOST".

Other options are:

-a: Abort after 10 consecutive drops
-d: Socket level debugging
-g: Use this gateway as an intermediate hop (uses LSRR)
-S: Set start TTL (default 1)
-m: Set maximum TTL (default 30)
-n: Report IP addresses only (not hostnames)
-p: Use an alternate UDP port
-q: Set the number of queries at each TTL (default 3)
-r: Set Dont Route option
-s: Set your source address
-t: Set the IP TOS field (default 0)
-u: Use microsecond timestamps
-v: Verbose
-w: Set timeout for replies (default 5 sec)
-A: Report AS# at each hop (from GRR)
-M: Do RFC1191 path MTU discovery
-O: Report owner at each hop (from DNS)
-P: Parallel probing
-Q: Report delay statistics at each hop (min/avg+-stddev/max) (ms)
-T: Terminator (line end terminator)
-U: Go to next hop on any success

This is not the "normal" version of traceroute, this is the traceroute program maintained by Ehud Gavron at It is based on the Van Jacobson/BSD traceroute with additional features including AS lookup, TOS support, microsecond timestamps, path MTU discovery, and parallel probing.