How do I disable telnet sessions from the wan adapter but allowing telnet access from the lan network.
VTY is short for "Virtual Terminal" (old system name for terminals is TTY).
VTY handles Telnet and SSH (for IOS that supports SSH)
Line Console is the serial port on the front.
1) Add an ACL to your WAN interface
ip access-list ext InboundACL
deny tcp any any eq telnet
permit ip any any
int s 1/0
access-g InboundACL in
2) Create an ACL and apply it to the Line VTY.
access-list 10 permit 10.1.1.0 0.0.0.255
line vty 0 4
access-class 10 in
That should do it for a rough sketch, although you'll need to modify for your environment. I would recommend disabling telnet altogether and going with SSH, too.
Hope this helps, rate if it does,