Hi i use sify in ubuntu ....
This is how you get your connection going
->Get your sify client for Linux ..... there are many 3rd party clients also available from independent devs , like super sify .... but i recommend the official sify client ....
->Copy your TCP/IP settings such as Subnetmask,gateway and ip address from your windows
->Enter your TCP settings and create a new connection in your Network manager (Linux) .... If its successful ,your lan should be connected
->Install your Client .... You may require some additional files as it may say that some additional files may be needed for it to work ...... You can then use it after you log in using your client