RE: Stopping the telnet service

From: Scott Morris (swm@emanon.com)
Date: Mon Aug 23 2004 - 16:44:56 GMT-3


The "service" is one of those built-in things. But you can control it. The
ACL listed is one way.

The other is turning off the input transport...

line vty 0 4
 password cisco
 login
 transport input none
!

Works:
Emanon-R2#telnet 24.24.24.24
Trying 24.24.24.24 ... Open

Password required, but none set

[Connection to 24.24.24.24 closed by foreign host]
(Set the PW)
Emanon-R2#telnet 24.24.24.24
Trying 24.24.24.24 ... Open

User Access Verification

Password:
Emanon-R1>Test 1 works
            ^
% Invalid input detected at '^' marker.

Emanon-R1>exit
(did the transport input none command)
[Connection to 24.24.24.24 closed by foreign host]
Emanon-R2#telnet 24.24.24.24
Trying 24.24.24.24 ...
% Connection refused by remote host

Emanon-R2#

HTH,

 
Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, CISSP,
JNCIP, et al.
IPExpert CCIE Program Manager
IPExpert Sr. Technical Instructor
swm@emanon.com/smorris@ipexpert.net
http://www.ipexpert.net
 

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
laurent.metzger@bt.com
Sent: Monday, August 23, 2004 1:06 PM
To: geert.nijs@simac.be; ccielab@groupstudy.com
Subject: RE: Stopping the telnet service

hi Geert,
 
we are doing:
 
line vty 0 16
access-class 1 in
 
access-list 1 deny any
 
This will not stop the telnet service but it will be impossible to telnet
the router.
 
Prettig avond verder, Laurent

        -----Original Message-----
        From: nobody@groupstudy.com on behalf of Geert Nijs
        Sent: Mon 8/23/2004 5:14 PM
        To: Group Study
        Cc:
        Subject: Stopping the telnet service
        
        

        Hi group,
        
        In configuring a router for SSH access only, i was wondering if you
can
        stop the telnet service on a router.
        Since, when you configure SSH access only with "transport input
ssh",
        the telnet service still runs,
        and, if you do a port scan on the router, you will notice that port
23
        can still be "seen".
        
        How can i configure the router not to respond to port 23 at all ?
        
        The best solution would be to stop the telnet service all together,
if
        possible.
        I think that configuring an ACL on all interfaces, denying telnet,
would
        also work. But i'll have to test that
        in the lab.
        
        Any other ideas ?
        
        Regards,
        Geert
        
        
        
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