Firstly this question is about router IOS not PIX which does not support
conduits
Secondly Cisco now, and has for quite a while, supports numbered
extended access-lists which allow adding, deleting and general editing
of access-list
________________________________
From: Chris Morse [mailto:chris.morse@planexpress.net]
Sent: 10 November 2004 05:12
To: Chad@mr-lew.com; Eric McCarty; Dennis Dimka; Dan Tesch; Firewalls
Securityfocus
Subject: RE: Router config question
I have to ask, perhaps out of sheer ignorance; Why use Acces-list? Cisco
pushed them in an effort to depracate conduits, but I can enter conduits
on the fly, wothout re-entering the entire ACL everytime. I really want
outside input on this. Got a few big configs to move. Your thoughts?
________________________________
From: Chad [mailto:chad@mr-lew.com]
Sent: Mon 11/8/2004 9:07 PM
To: 'Eric McCarty'; 'Dennis Dimka'; 'Dan Tesch'; 'Firewalls
Securityfocus'
Subject: RE: Router config question
Actually, shouldn't it read more like this:
Access-list 110 permit tcp any 10.0.1.10 255.255.255.255 eq 80
Access-list 110 permit tcp any 10.0.1.11 255.255.255.255 eq 25
Access-list 110 deny ip any any
Of course you would catch it when you hit enter on the router... ;-)
-----Original Message-----
From: Eric McCarty [mailto:eric@piteduncan.com]
Sent: Monday, November 08, 2004 5:22 PM
To: Dennis Dimka; Dan Tesch; Firewalls Securityfocus
Subject: RE: Router config question
Erm... Shouldn't this read :
Access-list 110 permit tcp 80 10.0.1.10 255.255.255.255
Access-list 110 permit tcp 25 10.0.1.11 255.255.255.255
Access-list 110 deny ip any any
And as stated before those ACL Entries were for a bug in Cisco's
ISO Software, if you are running the most current IOS Version for your
Router, the issue has been long fixed and you no longer need those
ACL's. However if you are running your router as a router & Firewall in
one you should definately consider Dennis's advice and remove all ACL's
and add only permits for what you need (web, ssh, ftp, etc. etc.) and
allow the implicit deny all to drop the rest.
Eric McCarty
-----Original Message-----
From: Dennis Dimka [mailto:dennis.dimka@manna.com
<mailto:dennis.dimka@manna.com> ]
Sent: Monday, November 08, 2004 1:28 PM
To: 'Dan Tesch'; Firewalls Securityfocus
Subject: RE: Router config question
This is a little sloppy. If you don't have a dedicated firewall
(and the
2611 is essentially your firewall) you should allow only what
you need in, and deny the rest. Not only is this leaps and bounds more
secure, it mitigates the need to deny specific ports. For example, if
you have a public mail and a public web server and email server...
Access-list 110 permit tcp 80 10.0.1.10 255.255.255.255
Access-list 110 permit tcp 24 10.0.1.11 255.255.255.255 Access-list 110
deny ip any any
The last line is already implied at the end of any access list,
but having it in your ACL reminds you of this, and also shows you a
HITCOUNT.
-----Original Message-----
From: Dan Tesch [mailto:dan.tesch@comcast.net
<mailto:dan.tesch@comcast.net> ]
Sent: Monday, November 08, 2004 7:23 AM
To: Firewalls Securityfocus
Subject: Router config question
Hello, I inherited a Cisco 2611 that I have been trying to clean
up and understand the config on.
For a while I have been wondering why the following were being
specifically blocked...
access-list 110 deny 53 any any
access-list 110 deny 55 any any
access-list 110 deny 77 any any
access-list 110 deny pim any any
I was doing some reading trying to learn about PIM and found
this link which references a DOS vuln.
http://securecomputing.stanford.edu/alerts/cisco-update-17jul2003.html
<http://securecomputing.stanford.edu/alerts/cisco-update-17jul2003.html>
Was this a way to circumvent the listed vuln.? the doc
references IOS below 12.3, as I am now above that - may I safely remove
these denys?
Thanks
