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--- workshops:nanopi_m4_iptables_geoblocking [2019/03/06 19:01] – created admin
+++ workshops:nanopi_m4_iptables_geoblocking [2019/03/06 19:07] (current) – admin
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 |NanoPI M4|Michael Pope|{{ :workshops:20181029-nanopi_m4.pdf |slides}}|
 |IP validation, IPtables, and GeoBlocking|Timothy 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