This is a real trivial question; has anybody come across ICMP reply message !X when tracing from a Linux box to a cisco device?
---unfortunatelly I have no visibility\Access of the Cisco box---
Does someone know what it means, this reply ICMP symbol is not in the normal cisco list.
This is a UNIX specific code, it should carry the same meaning of !A in Cisco, which means that Communication administratively prohibited. The network administrator has blocked traceroute at this router using something like Access-list for example.
One more thing.. here are the list of traceroute codes that you can see in a UNIX box,
Host unreachable. The router has no route to the target system.
Source route failed. You tried to use source routing, but the router is configured to block source-routed packets.
Fragmentation needed. This indicates that the router is misconfigured.
Communication administratively prohibited. The network administrator has blocked traceroute at this router.
Sometimes, with some versions of traceroute, you will see TTL warnings after the times. This merely indicates that the TTL value on the reply packet was different from what was expected. This probably means that your route is asymmetric.