RE: ip alias

From: ccie2be (ccie2be@nyc.rr.com)
Date: Thu May 26 2005 - 10:34:45 GMT-3


Live and learn.
 
Thanks Bob.
 
I like that. Much less cutting and pasting than the show ip int brief which
I had been using before.
 
Very Cool.
 
Tim
 
  _____

From: Bob Sinclair [mailto:bsin@cox.net]
Sent: Thursday, May 26, 2005 8:44 AM
To: ccie2be; '22Cent@gmail.com'; 'Group Study'
Subject: Re: ip alias
 
Tim,
 
I like to use the command SHOW IP ALIAS in order to get a short listing of
the IP addresses on each router.
 
For example:
 
R1#sh ip alias
Address Type IP Address Port
Interface 192.168.0.100
Interface 50.50.50.1
Interface 172.16.8.1
Interface 172.16.7.1
Interface 172.16.1.1
Interface 172.16.101.1
 
 I then past the list into notepad, and do a search-and-replace to get rid
of
 
"Interface "
 
Results in a nice list of IP addresses I can use for my TCL script.
 
Just to confirm your explanation, I added the following command to R1:
 
R1(config)#ip alias 192.168.0.105 23
 
And I was then able to telnet to the 105 address. Here is the subsequent
output:
 
R1#sh ip alias
Address Type IP Address Port
Alias 192.168.0.105 23
Interface 192.168.0.100
Interface 50.50.50.1
Interface 172.16.8.1
Interface 172.16.7.1
Interface 172.16.1.1
Interface 172.16.101.1
 
Thanks!
 
Bob Sinclair
CCIE #10427, CCSI 30427, CISSP
www.netmasterclass.net
----- Original Message -----
From: ccie2be <mailto:ccie2be@nyc.rr.com>
To: 'Bob Sinclair' <mailto:bsin@cox.net> ; '22Cent@gmail.com' ; 'Group
<mailto:ccielab@groupstudy.com> Study'
Sent: Thursday, May 26, 2005 8:11 AM
Subject: RE: ip alias
 
Ray,

I think this command falls into the "Stupid Router Tricks" category.
However, nothing in the lab blueprints excludes such things so it could be
there.

That said, here are my notes on it.

Its possible to have a router accept telnet requests to an ip host address
that doesn't exist on any of the router's interfaces. For example, assume
that the dns entry for a router is entered with the wrong ip address. If
you configure ip alias <wrong ip> 23, the router will accept that. (See IE
lab 4) The wrong ip address should only be wrong in the host portion of the
address- the subnet should exist on the router. Another possible way to
achieve the same effect is to use 2ndary addressing on an interface. (See
IE lab 7)

Bob,

Any chance you could post an example of how to use this command to collect
addresses for a TCL script? Am I missing something obvious cause I don't
see how this command would help?

TIA, Tim

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Bob
Sinclair
Sent: Wednesday, May 25, 2005 9:25 PM
To: 22Cent@gmail.com; Group Study
Subject: Re: ip alias

Not sure of its intended use. I use it to collect IP addresses for my TCL
scripts. Seems to minimize unnecessary characters. It also displays
dynamic
addresses, those configured via static NAT or DHCP.

Bob Sinclair
CCIE #10427, CCSI 30427, CISSP
www.netmasterclass.net

  ----- Original Message -----
  From: 22Cent@gmail.com
  To: Group Study
  Sent: Wednesday, May 25, 2005 9:15 PM
  Subject: ip alias

  Hi group,
  What is the correct usage of the ip alias command. I was once told it
  can be useful in the lab. Any thoughts?

  TIA
  Ray

  R1(config)#ip alias ?
  A.B.C.D IP address to alias to a port

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