I was reading some security related blogs and write ups in internet and I started going for the RFCs instead, but they are huge, therefore impossible to learn all of them. I see those below as very important ones:

  1. RFC 761 Transmission Control Protocol

  2. RFC 791 Internet Protocol

  3. RFC 792 Internet Control Message Protocol

  4. RFC 2616 Hypertext Transfer Protocol 1.1

  5. RFC 768 User Datagram Protocol

Am I missing any?

  • 3
    One shall not forget the RFC3514, an elegant solution against hacking.
    – Yuriko
    Commented Mar 9, 2016 at 8:47
  • 3
    You have just listed RFC covering a small part of communication protocols. If you are learning application security these may be (mostly) irrelevant. If you intend to learn security I would strongly recommend that while reading RFCs is useful to gain in depth knowledge of particular areas, they should not be the basis of your learning!
    – Rory Alsop
    Commented Mar 9, 2016 at 9:46

3 Answers 3


Learning Basic Networking is very important.These are protocols specific RFC's , to gaing in-depth knowledge about a particular protocol. You can approach by :

for example IP RFC 791

First study and learn IP from IP RFC,or various resoures.

After Having the knowledge of IP , you can find out what are the different security problems related to IP.

For example in its design , its header , various ways an attacker can manipulate and use IP protocol,spoofing,replay packets etc.

Than finding the safety measures required.

This may lead you to ipsec,firewall(iptables). Then finding how ipsec saves you.

For that go for IPsec RFC and find out how it solves various security problems you have encountered earlier. If ipsec is not the complete solution find out more.

You can keep on researching on DNS,HTTP etc

Hope it helps !


There is no such thing as the most important RFC's. Practically every RFC describing an actually used protocol is relevant, because often you can find security problems in the implementation of rarely used parts of the RFC or when dealing with invalid or inconsistent data.

If you want to restrict yourself to analyzing the lower layers then the RFCs for TCP, UDP, IP etc are a must. If you want to deal with common application protocols then RFC's for HTTP, SIP etc are useful and you would not even need a deeper understanding of TCP etc to analyze these application protocols. And if you are dealing with file formats then you will often don't find any RFC's at all because these have either no public documentation at all or are not documented as RFC's. Same is true for lower level protocols (Ethernet, WiFi, LTE...).


TCP/IP Stack is very important. Also check out the following: RFC 5246 (tls 1.2) and tls 1.3 which is in draft.

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