i want my users to acess unix server through internet,using telnet or netterm. i hade a microwave 64 kbps dedicated link for internet .my internet connection is connected to a router ,that router is the gateway.the isp has provided a static ip for acessing internet which is defined at the serial port of cisco(2500)router .if i hade to assign a static ip where would i asign,either on serial port of router or on lan card of server. all the users want is just to put ip in tellnet and connect to server after connecting to internet,and server ask for authentication,after putting there id:pasword they can acess.

You don't need to assign any static route if the server is directly attached to your ethernet interface on your cisco router. There must be an ip address on your e0 interface on the router then it will already know about the directly attached network. Just make sure your server has an ip address on it. If it doesn't then you should give it one. Both the router interface and your server both need ip address!