Just to toss out an idea: one thing I've seen on some blogs to discourage this sort of sock-puppetry is to display a hash of the posting IP along with either all posts or just those from unregistered / anonymous commenters. That way you know that the "dazzling witty" comment that 4 "different" commenters are all "independently" praising all came from the same source.

Actually, I had been considering doing exactly that. I hadn't seen it elsewhere (I don't read blogs much) but my plan was to make the hash so that, for example, if the first three octets of the IP match, then the first three chunks of the hash would match since many have dynamic IPs (but the hashing of each octet would depend on the previous octets so the hashing wouldn't be trivial to reverse).

I suspect even a hash of the source IP being displayed on non-anonymous nodes here would be greeted by complaints from some people. But I'd also like to discourage the "registered user pretending to be anonymous" sham. But I've also posted anonymously for good reason several times. Perhaps the ability to see the hash of the IP of non-anonymous nodes could be a level power or there could be a level power that allows comparing the source IPs of two specific nodes?

In the end, it didn't make it to the top of my to-do list in part because we've banned the IPs of the two most persistent anonymous trolls so the benefit was limited for now. I somewhat envy wikipedia's position of noting IPs of anonymous contributors from the beginning.

- tye        

...my plan was to make the hash so that, for example, if the first three octets of the IP match, then the first three chunks of the hash would match

That sounds like a nice goal, but one thing to be wary of is making brute force attacks too easy. If you publish a hash of only the first three octets of an IP address, that's a somewhat smaller range of numbers I have to plough through to guess what the original numbers are. I get an even bigger advantage if I check only the blocks that I know are registered to some organization and look first at blocks from English speaking countries, etc.

Just a thought.

If you really want to have access to multiple IP -addresses and remain fully anonymous then TOR is easily available, so even displaying a hash of the IP-address would not stop anyone from spoofing their identity.

Personally I just think it is not worth the bother. If some people wish to speak to themselves, I don't mind. The sooner you leave them alone, the faster they disappear.

CountZero

A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James