> tcpdump -pnvvvi re0 host 172.16.3.23 and port 23
tcpdump: listening on re0, link-type EN10MB (Ethernet), capture size 96 bytes
13:43:05.735906 IP (tos 0x0, ttl 64, id 28336, offset 0, flags [DF], proto TCP (6), length 60, bad cksum 0 (->766e)!)
    213.108.209.9.56395 > 172.16.3.23.23: Flags [S], cksum 0x55cc (incorrect -> 0xa9a0), seq 2537770425, win 65535, options [mss 1460,nop,wscale 3,sackOK,TS val 2271281157 ecr 0], length 0
13:43:05.744175 IP (tos 0x0, ttl 61, id 60664, offset 0, flags [none], proto TCP (6), length 60)
    172.16.3.23.23 > 213.108.209.9.56395: Flags [S.], cksum 0x5225 (correct), seq 3988821645, ack 2537770426, win 8192, options [mss 1460,nop,wscale 0,nop,nop,TS val 177693 ecr 2271281157], length 0
13:43:05.744203 IP (tos 0x0, ttl 64, id 28338, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->7674)!)
    213.108.209.9.56395 > 172.16.3.23.23: Flags [.], cksum 0x55c4 (incorrect -> 0x7d5b), seq 1, ack 1, win 8326, options [nop,nop,TS val 2271281165 ecr 177693], length 0
13:43:05.752910 IP (tos 0x0, ttl 61, id 60666, offset 0, flags [none], proto TCP (6), length 55)
    172.16.3.23.23 > 213.108.209.9.56395: Flags [P.], cksum 0x65d8 (correct), seq 1:4, ack 1, win 8192, options [nop,nop,TS val 177693 ecr 2271281165], length 3 [telnet DO TERMINAL TYPE]
13:43:05.856745 IP (tos 0x0, ttl 64, id 28343, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->766f)!)
    213.108.209.9.56395 > 172.16.3.23.23: Flags [.], cksum 0x55c4 (incorrect -> 0x7ceb), seq 1, ack 4, win 8326, options [nop,nop,TS val 2271281274 ecr 177693], length 0
13:43:35.943279 IP (tos 0x0, ttl 64, id 28760, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->74ce)!)
    213.108.209.9.56395 > 172.16.3.23.23: Flags [F.], cksum 0x55c4 (incorrect -> 0x0be8), seq 1, ack 4, win 8326, options [nop,nop,TS val 2271310204 ecr 177693], length 0
13:43:35.946494 IP (tos 0x0, ttl 61, id 60668, offset 0, flags [none], proto TCP (6), length 52)
    172.16.3.23.23 > 213.108.209.9.56395: Flags [.], cksum 0x0c32 (correct), seq 4, ack 2, win 8192, options [nop,nop,TS val 177753 ecr 2271310204], length 0
13:43:35.948741 IP (tos 0x0, ttl 61, id 60670, offset 0, flags [none], proto TCP (6), length 52)
    172.16.3.23.23 > 213.108.209.9.56395: Flags [F.], cksum 0x0c31 (correct), seq 4, ack 2, win 8192, options [nop,nop,TS val 177753 ecr 2271310204], length 0
13:43:35.948756 IP (tos 0x0, ttl 64, id 28761, offset 0, flags [DF], proto TCP (6), length 52, bad cksum 0 (->74cd)!)
    213.108.209.9.56395 > 172.16.3.23.23: Flags [.], cksum 0x55c4 (incorrect -> 0x0ba7), seq 2, ack 5, win 8325, options [nop,nop,TS val 2271310209 ecr 177753], length 0