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
