Check out the following thread as preliminary info. You may also need additional equipment such as AUI/Ethernet transcievers, a switch, straight through and/or crossover Category-5 patch cables, and Cisco console kit.
»Setting up Cisco 2514 as DSL Firewall
Keep in mind that Ethernet ports (Ethernet interfaces) of any 2500 series router are the AUI ports, NOT the RJ-45 ports. The RJ-45 ports are for CONSOLE and AUX (Auxilary) access which are for totally different situation. This is where the AUI/Ethernet transcievers come in handy.
You may also need the latest IOS and the maximum size of DRAM and flash memory (16/16 MB). It is suggested to always max out the DRAM and flash memory size before installing latest IOS. This way there should be no encounter problem of insufficient memory space.
»ssh configuration help