Kerberos - Claims Based Authentication Sharepoint 2010 Get current user credentials

I have a webpart that needs to connect to another site collection (on a remote server but same domain, different port) using the current user credentials. The user exists in both site collections, they are configured as i said in the title, kerberos/claims based.

First i was getting 401 error forbidden, i then changed the web.config section :

<add key="aspnet:AllowAnonymousImpersonation" value="false" />

I don't have the 401 error anymore, but when i use debug mode,  I notice that the connected user is not my account but the system account.

What can I do to get this fixed please?