LFS211 Lab 4.1

fsierra

the Lab instructs to use:
# tcpdump -i lo proto ICMP

If localhost is getting resolved to IPv6 (::1), tcpdump won't show any traffic
Following has to be used instead:
# tcpdump -i lo icmp6

using proto, or uppercase results in an error:

$ sudo tcpdump -i lo proto ICMP6
tcpdump: unknown ip proto 'ICMP6'
 
$ sudo tcpdump -i lo proto icmp6
tcpdump: can't parse filter expression: syntax error

Tested on Debian 12, tcpdump version 4.99.3, libpcap version 1.10.3 (with TPACKET_V3)