Here is my _very basic_ configuration of a Cisco router running IOS. Just remember to change all {VARIABLE} to the correct value including the {} part.

This will result in an all basic configured router, running SSH and with a user you can use to log in through SSH.

Router> enable

Router# configure terminal

Router(config)# hostname {ROUTER_NAME}

Router(config)# enable secret 0 {ENABLE_PASSWORD}

Router(config)# interface fastEthernet 0/0

Router(config-if)# ip address {IP_ADDRESS} {SUBNET_MASK}

Router(config-if)# full-duplex

Router(config-if)# speed 100

Router(config-if)# no shutdown

Router(config-if)# exit

Router(config)# username {USERNAME} privilege {PRIVILEGE_LEVEL} secret 0 {USER_PASSWORD}

Router(config)# ip domain name {DOMAIN_NAME}

Router(config)# crypto key generate rsa
How many bits in the modulus [512]: 2048

Router(config)# line vty 0 4

Router(config-line)# login local

Router(config-line)# transport input ssh

Router(config-line)# exit

Router(config)# ip routing

Router(config)# exit

Router# show running-config

Router# copy running-config startup-config
Destination filename [startup-config]? [PRESS_ENTER]

Router# exit