Can someone pls explain to me what is the purpose of port numbers 2000, 3000, 4000? For example, I know if I use port 2097 (2000 + 97) using the example below, I can do a reverse telnet with serial3/0 interface. Are the port numbers (2000/3000/4000) user definable? When should I use 2000 or 3000 or 4000? Thank you.
# telnet a.b.c.d 2097
description Connected to TNT GHU
no ip address
transport preferred telnet
transport input telnet
transport output telnet
Tty Typ Tx/Rx A Modem Roty AccO AccI Uses Noise Overruns Int
0 CTY - - - - - 0 0 0/0 -
97 TTY 2400/2400 - inout - - - 52 3 0/0 Se3/0
line numbering is platform dependent.
in C3600 should be from 0 to N with 32 positions for each slot so 97 and line 3/0 are a good match
in older routers it was different and aux number changed depending on router effective installed modules.
for 1800,2800, 3800
you should use 2000+line# for reverse telnet, the other port ranges 3000, 4000 have different use
I couldn't find a link at the moment but this is sure
they may be used for X.25 or LAT protocol translation
Hope to help
I found an example of port 4321 used for Stream TCP (see below). Is the port number range 4000 meant for Stream TCP?
In the following procedure, a line is configured so that any connection into it is automatically connected using Stream TCP to the application server at the specified IP address and TCP port (IP address 10.1.2.3 and TCP port 4321 in the examples).
I found a previous posting. It answers my question.
2000 normal TELNET (full options negotiations, remote echo)
see RFC-854, also stuff on TELNET in RFC-1123
3000 normal TELNET to rotary
4000 raw TCP (stream) - no TELNET NVT. See RFC-793.
5000 raw TCP (stream) to rotary
6000 TELNET binary mode - see RFC-856
7000 TELNET binary mode to rotary
8000 forward Xremote
9000 reverse Xremote
10000 reverse Xremote to rotary
telnet = CR LF
binary = CR NULL 6000
stream = No negotiations 4000
Stream would usually be to a printer; binary would usually be to a host application that is running.