Created On 09/26/18 13:49 PM - Last Modified 02/07/19 23:45 PM
tracepath is a Unix/Linux-based utility similar to traceroute. However, the differences between the two are
tracepath does not require users to have root privilege.
tracepath uses (and only uses) UDP with random high port. traceroute (on Unix/Linux) by default also uses UDP with range destination port 33434-33534, but has an option to switch to ICMP (Windows traceroute always use ICMP).
Note: This is applicable for PAN-OS 5.0 or later.
If a security rule only allows application "traceroute" and service "application-default" and there is no other subsequent rule to permit tracepath traffic then its UDP packet will get dropped.
Explanation: This is because tracepath uses UDP with random high port. If a service is set to "application-default", tracepath could get denied because in App-ID signature the standard port range for traceroute only includes icmp/any and udp/33434-33534.
There are two possible solutions:
1) Configure the security rule to allow application "traceroute" and service "any". You will also need to allow application "icmp" and "ping" as well because these two are application dependency for traceroute.
2) Instruct users to run tracepath with a specific "starting" destination port 33434. Note in the traffic log, the destination port increments from 33434 for each hop. Again, allowing application icmp & ping is still needed due to the traceroute application dependency.