Telnet through firewall

Hi.

If you are reading this, I would be very appreciated if you could help me.

I have a firewall socks connecting our client desktops PCs to a Cisco router (using IOS), which in turns connected to the Internet.

Right now, I am trying to find ways to telnet to my router. The problem is that each time I opened a telnet port at my socks firewall, the firewall crash.

What happened actually ?