Redirect and log in to external SSL form

I'm not sure if this is possible, but have the following problem...

Have created a website which I'd like to link to an external "Members" website at https://www.memberswebsite.com/

Is it possible for user to supply login credentials on my site and then be redirected and logged in to the members website?

Was hoping to do this by posting credentials to the members website login form but I have a feeling this is not possible.

Login form on members website is also https and using NTLM authentication I'm fairly sure.

Ideas?

Th开发者_StackOverflowank you :)

It's possible, it's just not a great idea for a number of reasons:

1. App 1 is handling plain text credentials and manually recreating requests with them
2. The certificate of App 2 can't be inspected by the user before trusting the site with their credentials
3. In an NTLM environment, you want to try and defer to integrated authentication wherever possible (there are numerous SO threads on this)

I'd suggest allowing them to authenticate directly to the members site. It's not clear from your question but if they can use NTML, can they not use integrated Windows authentication on the second site? And why would you want to authenticate to App 1 and then manually pass credentials anyway?