(29 Jan 12, 06:29PM)Dynamite Wrote: I don't really understand the CIDR ranges very well.Well, the details can get a little complicated (bitwise operations and such), but it comes down to this usually:
1) The lower the number, the more IPs are affected. /24 affects 254 IPs, /16 affects 65534.
2) The number of hosts ("IPs") affected is calculated as 2^(32-NumberBehindSlash) -2
3) Don't go higher than /16, or in really extreme cases maybe /15, because at that level you'll be banning entire ISPs. (EDIT: this is for blacklists ofc. For something like a nickname blacklist, /8 would work too)
4) Trial and error - start with something low, like /19, and if that doesn't do it, go further.
5) Complete Idiot's (a.k.a. mine) estimate on ranges (don't take this too serious):
/8 ... a country
/14 ... a (medium-sized) ISP
/16 ... a small ISP, or a big ISP's local subnet
/19 ... might still catch the guy, but often not
(29 Jan 12, 06:29PM)Dynamite Wrote: Also, how do I figure out what this guy's IP is? I have no idea, and I'm not an admin on the server./whois