I have a parent portal which gets the username/password via login page. From results of user and role the user will be able to link to other child portal sites. How can I pass the login information to the child portal site so user does not have to login in yet again. Thanks.

You will need to add a module that enables "single signon" to a group of DotNetNuke portals. Data Springs' Dynamic Login module will do this for you.

I've never implemented this sort of solution on a site, so know only what I read. But, Data Springs is known as a quality developer, and Dynamic Login is known as a high quality module. If you Google "DotNetNuke Single Sign On" you will find some other solutions. But, I can't vouch for any of them, simply because I am not familiar with the modules.

I was going to ask this question myself, so thanks again, Joseph. Actually, I think Lee has done a tutorial on the Dynamic Springs Login module (if memory serves me correctly) but I've never got around to viewing it, so will do that now.