ICMP Packets.

john_smith@rd.qms.com john_smith@rd.qms.com
Fri, 05 Jun 98 08:01:19 -0600


        I knew I had seen this thread before.  Searched my personal 
     archives and came across it in the Firewalls Digest (V6 #295, #299, 
     #304 and #305) under the thread titled "what ICMP should i allow 
     through?".  Based on that discussion we modified our filter rules as 
     follows:
     
     Inbound Allow:
     
     - echo (type 8/code 0)
     - paramter-problem (12/[0|1])
     - source-quench (4/0)
     - ttl-exceeded (11/[0|1])
     
     Deny all other inbound ICMP.
     
     Outbound we allow all ICMP packets.
     
        This complies with our policy of permit all outbound and deny all 
     inbound except what is specifically permitted.  This list works *for 
     us* and does not seem to cause any connection problems (at least no 
     customer connectivity complaints).
     
        If any of you spot any obvious problems with this please point them 
     out.
     
     jcs
     
     John C. Smith
     Sys Admin/Jack-of-all-trades
     QMS, Inc.
     1 Magnum Pass
     Mobile, AL  36618, USA
     (334) 633-4300
     john_smith@rd.qms.com