29th October 2018

Talk Speaker Slides
NanoPI M4Michael Popeslides
IP validation, IPtables, and GeoBlockingTimothy Rice

IP Validation Notes

A couple of people asked to have a closer look at Cider, you can find it at:

https://notabug.org/cryptarch/cider

If you're interested in the Hacker News article which opened my eyes to the craziness of IP address parsing, you can find it here:

https://news.ycombinator.com/item?id=6580592

Note that the IPv4 spec acknowledges IP addresses in either octet-dot or unsigned 32-bit integer form:

https://tools.ietf.org/html/rfc791#section-2.3

Thus, the abbreviations from that Hacker News article were not anticipated and are completely implementation dependent. You can inspect how implementations can differ by comparing the respective iptables and ipset interpretations of 127.1/32

For a more recent example illustrating IP addresses in a form that seems unconventional, these will all take you to a certain popular website:

http://1000849999 http://0x3BA7C24F http://07351741117

To get started with ipset, this is the Arch Linux wiki article I referred to:

https://wiki.archlinux.org/index.php/Ipset