03-26-2009 01:32 AM - edited 03-11-2019 08:10 AM
Hi guys,
telnet x.x.x.x 20yy
yy is the decimal line number to which you want to connect and 20 is default.
What's that 20 means?
May I know please?
Thanks!
=)
03-26-2009 07:39 AM
It's the virtual line number assigned by the device. A show line will show the virtual lines on the system.
Hope that helps.
03-26-2009 06:50 PM
Yes, a show line command will show the virtual lines on the system, but once you ping the IP address it will also show you the virtual line WITH THAT NUMBER 20 inside a parenthesis. Am I right?
If it's line 34 it will say, when you're trying to ping, 2034.. Is that default number 20 (with virtual line 34) assigned by the device? Is that what you mean? Well, I still didn't get it. Apologize.
Thanks.. =)
03-27-2009 02:17 AM
Hi guys please I need a little help.. Thanks.. =)
03-27-2009 03:02 AM
Hi,
The number 20yy (ie 2034) is the TCP port number that you're connecting to
Normally when you telnet you go to port 23 but if you put a port number on the end you'll connect to another TCP socket. ie
telnet 10.1.1.1 goes to port 23
telnet 10.1.1.1 25 goes to smtp
telnet 10.1.1.1 80 goes to http
etc.
TCP ports 0-1023 are well known reserved port numbers and so cisco have just added 20 to the front of the line number in order to aviod the lower range of TCP ports.
Therefore the number 20 is just arbitary. See link below for a full list of TCP ports
http://www.iana.org/assignments/port-numbers
Regards
03-27-2009 06:31 AM
When you install a card with A/S lines, new lines are installed (ie 20-27 for an 8 port card). Here's a link on the line numbering by platform.
http://www.cisco.com/en/US/products/hw/routers/ps274/products_tech_note09186a00801ca70b.shtml
To establish a reverse Telnet session to an asynchronous line, determine the IP address of your LAN (Ethernet) interface or loopback address, then enter a Telnet command to port 2000 + n on the access server, where n is the installed asynchronous line number. For example, to connect to the console of the router attached to line 1 (which is really asynchronous line 20)-
router# telnet 172.16.1.10 2020
Trying 172.16.1.10, 2020 ... Open
router1>
The 2000 is something decided to use and AFAIK you can't change it.
Hope that helps.
03-30-2009 02:10 AM
Thanks guys!
Thanks so much... =)
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