Up to 3 “telnet” interfaces can be configured on XRouter. The general purpose one defaults to TCP port 23. There's a sysop-only one, usually on TCP port 513, and one for machine-to-machine interactions, the so-called “Telnet Proxy”.

Here's a typical login to port 23 from a Linux terminal:

If you so desire, the “normal” telnet interface can be opened to the wider world, because connections to that port do NOT have “sysop” privileges, as can be seen by the reduced command set in the following example: