tcpdump filter not functioning correctly with igb on FreeBSD 11.1

[Eugene Grosbein]

07.02.2018 5:10, David Athay wrote:

> # /usr/local/sbin/tcpdump --version
> tcpdump version 4.9.0
> libpcap version 1.8.1
> OpenSSL 1.0.2n-freebsd  7 Dec 2017
> 
> Still same weirdness.
> 
> # /usr/local/sbin/tcpdump -ni igb0 not port 22 | less
> tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
> listening on igb0, link-type EN10MB (Ethernet), capture size 262144 bytes
> 22:03:28.941870 IP X.X.X.X.22 > 77.100.156.Y.52743: Flags [P.], seq 417632730:417632918, ack 196056259, win 1026, options [nop,nop,TS val 602028380 ecr 730520401], length 188
> 22:03:28.969328 IP 77.100.156.Y.52743 > X.X.X.X.22: Flags [.], ack 0, win 4093, options [nop,nop,TS val 730520446 ecr 602028380], length 0
> 22:03:28.969342 IP 77.100.156.Y.52743 > X.X.X.X.22: Flags [.], ack 188, win 4090, options [nop,nop,TS val 730520447 ecr 602028380], length 0
> 
> # /usr/local/sbin/tcpdump -ni igb0 not host 77.100.156.Y | less
> tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
> listening on igb0, link-type EN10MB (Ethernet), capture size 262144 bytes
> 22:05:58.807570 IP X.X.X.X.22 > 77.100.156.Y.52743: Flags [P.], seq 418507510:418507698, ack 196060707, win 1026, options [nop,nop,TS val 602178246 ecr 730669128], length 188
> 22:05:58.831887 IP 77.100.156.Y.52743 > X.X.X.X.22: Flags [.], ack 0, win 4093, options [nop,nop,TS val 730669159 ecr 602178246], length 0
> 22:05:58.838645 IP 77.100.156.Y.52743 > X.X.X.X.22: Flags [.], ack 188, win 4090, options [nop,nop,TS val 730669159 ecr 602178246], length 0
> 
> # /usr/local/sbin/tcpdump -ni igb0 host 77.100.156.Y
> tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
> listening on igb0, link-type EN10MB (Ethernet), capture size 262144 bytes
> ^C
> 0 packets captured
> 140 packets received by filter
> 0 packets dropped by kernel

802.1Q vlan header can be a reason for exactly such behaviour.
Please add -e flag to tcpdump flags and post output again.