RewriterRuleCollection' is ambiguous in the namespace 'DotNetNuke.HttpModules.Config

Solution is:

there must be some left over from DNN 3 I guess, I assume an old .dll file in the bin folder. Check it by deta, there shall be no old dotnetnuke...dll file EXCEPT dotnetnuke.Modules...dll

IS there any DNN class to take user machine ip address? How can i take user machine ip address?

You should be able to extract the user ip from the httprequest object i.e Request.UserHostAddress

How can i remove http access and use https after the user login?

log in as a portal admin and go to admin->site settings->advanced->ssl . If you check the "ssl enforced" checkbox, dotnetnuke will ensure that any pages marked as secure can only be accessed by https.

Cathal