Comment Spamming is one of the major problem faced by all the blog owners. Spammers are not interested to redirect your traffic but are trying to increase their (or their client's ) search engine ranking. By leaving comments on your site, the spammers' sites can achieve a slightly higher search engine ranking.Spammers don't want to degrade your site but they just want to get people to their sites and make a larger profit.
How to tackle this comment spamming ?
*) Don't ban specific IP address :
Once you got the spammer's IP address you would normally banned it, but it rarely helps you much as most comment-spammers make use of 'open proxies ' using which they have their spam comments, so you never be able to eradicate them from your site.
*) Don't allow to insert HTML code.
Spammers generally attack your site if you provide them any source for getting into your site such as inserting some html code or anything like that.
If you feel the need to allow the user to include links, there are a number of ways by which you can provide them this functionality, without making your site vulnerable to attack. The most common method is to inform the user that all URLs will be converted to links automatically, then convert any content that starts with http:// to a link.
*) Use Non-Descriptive Form Names.
Good programming requires the use of descriptive names, but in avoiding comment spam, you should stay away from names that describe a form's fields. Form element names like "Comment" make it too easy for spammers to access your comment system.
*) Use rel="nofollow" for All Links.
For any reason, you want to allow your visitor to include links in their comments, then don't forget to add rel="nofollow" tag, doing so you informs search engines bots to ignore the link, so the spammer gains no benefit from adding links in their comments.
