icmpinfo - interpret ICMP messages

icmpinfo [-v[v[v]]] [-n] [-p] [-s] [-l]

The output format is as follows (all on one line):

MMM DD HH:MM:SS ICMP_type[sub-type] < sender_ip [sender_name] > unreach_ip [unreach_name] sp=source_port dp=dest_port seq=sequence sz=packet_size

In normal operation, icmpinfo will only report on "weird" packets, mainly icmp_unreachable.

-v

Give information about all icmp packets, excepts pings.

-vv

Give about pings too (i.e. icmp_echo_reply).

-vvv

Include an ascii/hex dump of each packet

-n

Avoid name queries - just give IP addresses. (use this option when running unattended on name server hosts (to avoid possible looping))

-p

Avoid port number to service name decoding.

-s

Show the interface ip that received the packet. Usefull only if your host has several network interfaces. In this case an '- my_ip [my_name]' is added between the sender and unreach ip and name fields.

-l

Forks and use the syslog(3) facility to record events (recomended use). (root only option).