how to do Telnet to a router Cisco for UDP to port 500

[midence11]

can you help me to do Telnet to a router Cisco for UDP to port 500

[MHM Cisco World · Accepted solution]

You canot because telnet is tcp not udp.

If you decide to use tcp then nat solve your issue.

[Joseph W. Doherty]

As @MHM Cisco World correctly notes, telnet is TCP only.

However, if you have access to the utility Netcat (or one like it), it can use TCP or UDP (and different ports).

[Joseph W. Doherty]

"If you decide to use tcp then nat solve your issue."

BTW, NAT might not be needed in such cases.   I recall (?) some telnet programs will accept a destination port number, e.g. "telnet 1.2.3.4 500".