2009 Oct 11 - Sun

Traceroute Methods

Traceroute, in a nutshell, is about iteratively sending packets to the network with specific TTL (Time To Live) settings. The first round of packets uses a TTL of 1. The second uses a value of 2. The values are adjusted upwards each iteration until the destination responds, or the maximum number of hops has been evaluated.

The traditional form of pinging is to send out an ICMP type 8 packet. There are other forms:

• Windows 'tracert' uses ICMP type 8 with incrementing TTL
• Unix 'traceroute' uses UDP packets starting port 33434 through (33434 + - 1)
• TcpTraceRoute which uses TCP syn packets to penetrate firewalls and NAT systems

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