VTY stands for Virtual TeletYpe interface. It means you can connect to the daemon via the telnet protocol.
To enable a VTY interface, you have to setup a VTY password. If there is no VTY password, one cannot connect to the VTY interface at all.
% telnet localhost 2601 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. Hello, this is zebra (version 0.96) Copyright 1997-2000 Kunihiro Ishiguro User Access Verification Password: XXXXX Router> ? enable Turn on privileged commands exit Exit current mode and down to previous mode help Description of the interactive help system list Print command list show Show running system information who Display who is on a vty Router> enable Password: XXXXX Router# configure terminal Router(config)# interface eth0 Router(config-if)# ip address 10.0.0.1/8 Router(config-if)# ^Z Router#
'?' is very useful for looking up commands.