Hi All,
How i can make liferay portal site available on internet but user login , publishing content ,content approval process should be only for intranet users.

End users can view only portal site.Sign in portlet should be only available for intranet user so they can login ,publish content ,upload documents, approve content

Both site should be sync. If content is approved from intranet it should reflect into internet site.

could anybody give guidance how i can achieve.

Outside of Liferay you could probably setup a redirect to the login page if they are coming from within the network.

Inside of Liferay an option would be to set the Virtual Host for an "admin" organization. Then add the login page on the organization and a hook on login to redirect to your regular organization. Then internal users would use the different url.

mysite.com - regular organization/website
login.mysite.com or admin.mysite.com - login/admin site.

Personally I wouldn't want the distinction...

Sure, most of the time I'm in the office and access the site via the intranet.

But sometimes I'm travelling and would still want the ability to make the changes.

By limiting this ability to folks on the intranet, I wouldn't be able to admin on the road (without VPN in, etc.).

This is a common scenario. If intranet and Internet users are different, why not just create different roles?

I Do aggree with David and Hitoshi . but my requirment is content publishing and approval process should be through only intranet due to security reasons. if signIn button is avaiable on any pages then might be end user will also try to login. so i want to show signin page only for Intranet users not internet users.
could you please suggest me how i can check request is comming from intranet or internet.