This article was originally published in November, 2010.
I’m not entirely certain of the original source of this article — I found it on one site, but a quick search reveals that the original source is most likely this site, but I may be wrong. The author of that article says he took some of the info in that article (looks like more than “some” from where I sit) from this article: How to: Linux Iptables block common attacks
Related articles found on that site are Using iptables to secure a Linux based Asterisk installation against hack attempts and Securing Asterisk – Fail2Ban (and that latter article looks suspiciously similar to this one: Fail2Ban (with iptables) And Asterisk).
I don’t know how valid or useful any of this is, but if you are running iptables on your system (if you’re not sure enter iptables -V on the command line — it should show you the version of iptables that is installed, if it is installed) then you might want to check these articles out. And if you find an earlier source for any of these, let me know and I’ll include the links. I know that in the technical community sometimes information gets copied around, but would it kill you guys to give attribution and a link to the original source when you are lifting information (or even raw text) from someone else’s article?