Linux traceroute: Trace Packet Routes Across the Network

The traceroute command in Linux returns the addresses of machines and other network devices through which packets pass to reach a specific destination. This path is known as address route. 

Traceroute also has its own executable to operate on IPv6, called traceroute6.

Traceroute uses the time to live (TTL – Time To Live) of IP packets to force an ICMP TIME EXCEEDED response from each device the packet passes through to obtain the necessary information. 

Time to live determines the maximum number of devices a packet can traverse before being discarded. This parameter is necessary to prevent packets from wandering the network forever if their destination is not found. 

This command can investigate where connectivity with the ping command is failing, and when this happens, most of the time it may be a problem with the routes, or some ICMP packet filter.

The default TTL is 30 hosts.

The most common options are:

• -n: This option disables name resolution;
• -w sec: This option changes the default ICMP packet return wait time from 5 seconds;
• -f ttl: This option changes the default initial time to live value of a packet;
• -m max: Changes the default maximum number of devices that will be tested by traceroute.

Example:

$ traceroute www.kernel.orgtraceroute to www.kernel.org (204.152.189.116), 30 hops max, 40 byte packets 1  10.128.0.1  6.832 ms   8.702 ms   11.401 ms 2  10.11.0.254  13.013 ms   6.261 ms   6.993 ms 3  INF001010.enl-int.redeinfovias.net.br (200.150.1.10)  72.771 ms   71.875 ms   70.068 ms(...)13  r7-2.r8.pao1.isc.org (192.5.4.225)  236.927 ms   234.988 ms   232.748 ms14  r8-pao1.r3.sfo2.isc.org (192.5.4.233)  225.628 ms   214.758 ms   214.469 ms15  zeus-pub.kernel.org (204.152.189.116)  216.677 ms   219.898 ms   221.776 ms

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