Sample ICMP Denied

[denilsonsa]

Migrating this from https://bitbucket.org/denilsonsa/small_scripts/issues/5/sample-icmp-denied

Justin Novack created an issue 2013-10-21

The following is a sample output from OSX 10.8.5 when ICMP is explicitly filtered by a rule on a router.

Request timeout for icmp_seq 1
76 bytes from 10.15.37.33: Communication prohibited by filter
Vr HL TOS  Len   ID Flg  off TTL Pro  cks      Src      Dst
 4  5  00 5400 42ba   0 0000  3a  01 0fb4 10.13.12.25  10.19.22.25

(IPs have been changed to protect the guilty)

The sample is provided to help you with "TODO: Detect the following kinds of message and avoid printing it repeatedly."

Denilson Sá Maia commented 2013-10-21

Do you mean... This pack of 4 lines gets repeated for each ping?

Can you post a little more output, just to give me more context?

Justin Novack commented 2013-10-21

This is the response from "ping xx.xx.xx.xx" when an ACL on an intermediate router drops the ping packet or filters the reply packet.

The full FOUR (4) lines are displayed on each packet.

It won't happen often, but was just something I wanted to include in case you wanted to capture it.