Telnet is "bad", this is how to enable ssh and disable telnet login, and BTW we only want ssh v2 as v1 is vulnerable to several attacks:
When asked choose a least 1024bits for the key
hostname switch ip domain-name mydomain.tld aaa new-model crypto key generate rsa ip ssh version 2 line vty 0 15 transport input ssh
Remember to add ACL, this is always a good thing
access-list 99 permit 192.0.2.0 0.0.0.255 ipv6 access-list ACL-RESTRICTED-IN permit ipv6 2001:db8::/32 any line vty 0 15 access-class 99 in ipv6 access-class ACL-RESTRICTED-IN in
when you create your ACL, remember it's even better to only accept login from your network
Source and nice explanation of the banners : http://www.cisco.com/c/en/us/support/docs/security-vpn/secure-shell-ssh/...
OH! BTW if you use clogin/rancid to log into your equipments, make sure your MOTD does not have any # or the auto-enable won't work...
I told you : MOTD (with #) + SSH + clogin = no auto enable