Below you will find a link for James Summers' Packet Analysis Reference Guide. James created this many years ago when preparing for his GCIA certification. Some of you have likely encountered a version of this file. Unfortunately, many instances have removed the credits sheet up front that calls out the creator/collator of this wonderful guide.
Packet Analysis Reference Guide
Below, find links to web page versions of some of the key references from the full spreadsheet linked above.
HEX/DEC/ASCII Chart IP IPv6 TCP UDP ICMP DNS
James Summers has very graciously permitted me (Seth Misenar) the use and distribution of this file as part of SANS content. Please honor his hard work by ensuring that any copies you see/have/share all include his attribution, copyright, and contact information.