How To Detect Traceroute Attempts on your System

You can detect that an attacker is performing a traceroute on your system, if you see the following symptoms:

1. If you observe port scans on very high UDP ports. This symptom means that the attacker has performed a traceroute on your system. However, it could also mean a simply port scan. Either way, it signifies the fact that your system is being scanned.

2. If the packet-monitoring tool installed in your network, picks up several outgoing TTL-exceeding messages, then it is yet another sign that someone is doing a traceroute on your system.

3. If in these log files, you also observer an outgoing ICMP port unreachable error message, then it means that since a traceroute was done on your system and as the target system i.e. your system, was reached, it responded with this error message.

You can also find our more information on the attacker (if he performs a traceroute on your system) by simply studying the sniffer log files. If you observer the TTL values, then we can easily figure out the following information on the attacker by making use of OS detection techniques discussed earlier in this white paper:

1. The Operating System running on the attacker’s target system.
2. Number of hops away, the attacker is from you.