yesterday I have visited one link exchange network (I am not specifying name here) which provides guaranty of good link exchange partner and good ranking. I have gone into detail and checked how it works. They generally ask you to add one notepad or html file with read, write permission, that means they can add links to this file and can edit without your permission. After that they can create and search link partner form the data which has been specified by any user and which can also be wrong.

There is a big hidden danger in doing link exchange this way. it is necessary to analyze the quality of each website with you are making an exchange. So if you will join this kind of network, they will automatically add your links with their criteria which will be wrong in most cases. So my advise is not to use this kind of network or services

Very good information by doing automatic link exchange your site will get penalized by search engines.

I really appreciate this useful help,
Google also don't like software.