Packet filter to watch ICMP (ping) packets

August 20, 1999

SUMMARY:

This packet filter will show all pings arriving at or passing through the PortMaster(TM).

This tool is useful in debugging routing problems since often a ping's echo request will arrive at the destined host but the echo reply will have trouble returning. Using this packet trace filter at different points along the path can be very revealing in pinpointing the problem.

Command> add filter p
New Filter successfully added
Command> set filter p 1 permit icmp
Filter p updated
Command> set console
Setting CONSOLE to admin session
Command> ptrace p ext
Packet Tracing Enabled

# Example ptrace output of pings arriving at PortMaster
icmp from 192.168.148.1 to 10.0.0.3 type Echo Request
icmp from 192.168.148.1 to 10.0.0.3 type Echo Request
icmp from 192.168.148.1 to 10.0.0.3 type Echo Request

# Example ptrace output of pings passing a through PortMaster
icmp from 192.168.148.1 to 10.0.0.15 type Echo Request
icmp from 10.0.0.15 to 192.168.148.1 type Echo Reply

To disable the ptrace, enter the following commands: 

Command> ptrace
Packet Tracing Disabled
Command> reset console
Console RESET