From: Michael Snyder (msnyder@xxxxxxx)
Date: Sun Aug 19 2001 - 14:35:02 GMT-3
Ran across something that surprised the crap out of me. I was trying to
upload an ios image to a router behind a terminal server. Needless to say,
the escape characters and control characters blew the upload out of the
water.
So I started doing some research. Question, do you think blocking port 2001
on a terminal server Ethernet interface would block access to reverse telnet
line 1? Nope, you lose.
There's three sets of reverse telnet ports. In my case 2001-2016 are the
normal telnet ports, ports 4001-4016 are in streaming mode and ports 6001-6016
are in binary mode.
Try it. Telnet to port 4001 on your terminal server.
So what is telnet streaming and binary mode? I don't know, other than what
the names imply. My reference to steaming mode only said 'lack of telnet
flow control'.
Is there any Guru's out there who know the uses of these other reverse telnet
port sets?
BTW, I never did get the image uploaded. Did get 2 megs out of the 6 megs of
image size uploaded using port 4001 and x-modem-1k before it errored out.
Could have been my dialup connection that caused the errors. I drove 40 miles
the next day to go fix the problem.
Does anyone know the correct way to xmodem an image to a router via a terminal
server line?
BTW, in a thread last week, a question was what the other ctrl-shift-6
commands do. I found these listed as.
Ctrl^b Break
Ctrl^c Interrupt Process
Ctrl^h Erase Character
Ctrl^o Abort Output
Crtl^l Confirm you are at the host
Ctrl^u Erase Line
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