Ethernet
Example
This is a hex dump of a TCP keepalive.
fc aa 14 30 62 b6 44 d9 e7 ff 53 63 08 00 45 00 00 34 3f 75 40 00 36 06 c4 d6 c3 c9 09 25 c0 a8 b2 e1 56 33 ee 46 d5 3a fe 23 4b 11 33 3f 80 10 01 f5 23 8d 00 00 01 01 08 0a 8e 21 17 ee ab 59 29 30