How to keep idiots out of net forums?

Hi,
An acquaintance started his own small military history discussion website/forum a while ago but is plagued by the inevitable few idiots who post assorted neo-nazi racist and pro-terrorist junk etc, and he's asked my advice how to deal with them because he's not too hot on techy matters, (and neither am I!)
Shall I tell him to try banning them by deleting their registration from his site?
Won't they get round a ban by simply re-registering under another name?
How about banning their IP address, would that be a foolproof way of permanently stopping them getting back on the same computer or would they find a way round that too?
Any advice is appreciated

Whatever ban you try to put in place could more than likely be fooled, eg if you ban IP, if i don't have a static IP when it changes, you will not be blocking me anymore but potentially a legitimate user, could also use a proxy to by-pass.

I would start by adding validation to the comments section to search for keywords/key phrases and allow/block based on that.

You don't. If your friend has a discussion forum, then it is inevitable that there are going to be opinions that are unpopular. All you can do is delete them. Of course, then it is not really a 'discussion' any more, is it?

You simply let the spammers get bored. It's all you can do. Do your best to delete their posts and ban their usernames/IP addresses because eventually they'll realize that they're not going to get anywhere by spamming you and will move on to another forum.

Also, encourage your users to not reply to spam topics at all as 99% of the time all the spammers/idiots want is attention drawn to their topic/post.

..if you ban IP, if i don't have a static IP when it changes, you will not be blocking me anymore but potentially a legitimate user, could also use a proxy to by-pass...

About what percentage of all net users have a non-static IP?
Did they get it by asking their ISP for a non-static IP?
Why would anybody want to go non-static, is it better than static in some way?

..if you ban IP, if i don't have a static IP when it changes, you will not be blocking me anymore but potentially a legitimate user, could also use a proxy to by-pass...

About what percentage of all net users have a non-static IP?
Did they get it by asking their ISP for a non-static IP?
Why would anybody want to go non-static, is it better than static in some way?

I have no idea what the percentages are, nor would I want to know. In Australia, most ISP's dish out dynamic IP's and you have to ask for a static IP (and probably pay a bit more for it).

There is no difference between static and dynamic, there are benifits of having a static, that being it's one IP you have to remember to RDP home and can run servers such as Mail and Web, not saying you can't with dynamic, you would have to update your DNS though when you IP changed.

If I were you and you did want to be stricter on forum posts, I would put a check in place when the users hit post, it will either not let them post or remove the banned words, in doing that though you would want to let the users know what you have done, why you have done it.Will more than likely lose a few users too (taking away freedom of speech etc...).

A forum's Terms of Service or Rules for posting should make clear subjects or topics not allowed,and the consequences of posting them. As Members, by joining, tacitly or directly agree to abide by these as a condition of use of the forum, the strawman issue of freedom of speech does not apply. There are several levels of actions he can take, depending on the individual instance and its seriousness.
1. Remove the post. Generally a PM to the Member reminding him of the forum rules and the main purpose of he forum will prevent further instances. Some forum software has a "warn" function that can be used; consistency and transparency is the key for this process.
2. Ban the user, especially if the first level is not effective. Only the most persistent fanatic will attempt to re-register---most will go away and find another forum in which to post. Admittedly, it may take a couple of bans until he gets the idea he is not wanted.

There is really not much you can do against a person determined to post such stuff. Registering under a different Member Name or a different IP address cannot be prevented. All you can do is to get rid of the post and reban until the person gets tired and moves on.

what forum software is he using?? Most ive worked with have a new user registration so within so many posts you can approve or deny they post and ban the user.