Through the use of reverse telnet on such a device, IP-networked users can use telnet to access serially-connected devices. In the past, reverse telnet was typically used to connect to modems or other external asynchronous devices. Today, reverse telnet is used mostly for connecting to the console port of a router, a switch or other device. When I telnet to the IP of the DSL router I am port forwarded to the Terminal Server then I reverse telnet from there and then jump around from device to device. I need to find a way to Telnet directly to the Terminal Server and bypass the DSL router without having to purchase public IPs from the ISP. Jun 01, 2004 However, a much simpler option on some Cisco routers is to connect a console cable from the 'AUX' port on the device attached to the modem, to the CON or AUX port on the second device. Then you can dial in through the modem to your first device, and reverse Telnet through the console cable to get a session on the second device. May 09, 2005 If you connect one router's aux port to another device's console port, you can telnet to the router, then use reverse telnet to connect to the other device's console via.
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#sh argh
4 years ago
Congratulations, you got an NM-32A and a cheap octal cable for that 2621XM you had sitting around. Florida custom license plate form. Now you can remotely console into ALL THE THINGS.
But hold on! Enabling reverse telnet to access the serial ports on the NM-32A is insecure. The security guy even came by and told you to turn it off. What do?
Reverse Telnet Cisco Router Setup
Would you believe me if I told you that reverse SSH is a thing?
Would you believe me if I told you it's been available since IOS 12.4?!
Reverse Telnet Cisco Router
It's true! Just do this:
How does this work? Simple, instead of telnetting to port 2000+tty number for access to your serial ports, just append the tty number to the username you're logging in as. If my username is arghcisco I just do this from a shell prompt:
But how do you get the line number? Just do this:
Bonus: this works with SSH RSA keys if you have them enabled, so you don't even have to enter a password.
Reverse Telnet From Cisco Router
Reverse Telnet Configuration Cisco Router
Note: please set this up everywhere, it's like $50-100 for up to 32 console connections. I just got back from a 120 mile drive because someone forgot to connect the console port on something important to the network.