All fragmented packet is harmful?




Hello, all.


I read some documents that there are some cases that filter any fragmented packet at the border router using access-list like below.


http://www.cisconation.info/en/US/tech/tk648/tk361/technologies_tech_note09186a0080120f48.shtml


!
ip access-list extended ACL-INFRASTRUCTURE-IN
!
!--- Deny IP fragments using protocol-specific ACEs to aid in
!--- classification of attack traffic
!
deny tcp any any fragments
deny udp any any fragments
deny icmp any any fragments
deny ip any any fragments
!
!--- Deny all other IP traffic to any network device
!
deny ip any <infrastructure-address-space> <mask>
!
!--- Permit transit traffic
!
permit ip any any



So I'm not sure that it will be no problem to filter all fragmented packet or not
when my systems are web service.



Thanks in advance.

------------------------------------------------------------------------
Securing Apache Web Server with thawte Digital Certificate
In this guide we examine the importance of Apache-SSL and who needs an SSL certificate. We look at how SSL works, how it benefits your company and how your customers can tell if a site is secure. You will find out how to test, purchase, install and use a thawte Digital Certificate on your Apache web server. Throughout, best practices for set-up are highlighted to help you ensure efficient ongoing management of your encryption keys and digital certificates.

http://www.dinclinx.com/Redirect.aspx?36;4175;25;1371;0;5;946;e13b6be442f727d1
------------------------------------------------------------------------



Relevant Pages

  • Re: 3Com SuperStack 3 Firewall Content Filter Exploitable Via Telnet
    ... > The weakness exploited by this vulnerability is that the 3COM filter ... > of the HTTP request packet in order to fool the filter, ... are TCP fragments, but it's likely the box doesn't reassemble IP ...
    (Bugtraq)
  • Re: Unusual tcpdump output?
    ... > prg wrote: ... Had been using another tool past ... > I took this to mean a fragmented packet of 1432, ... You are getting the fragments as revealed by: ...
    (comp.os.linux.networking)
  • Re: VB Winsock OCX Error during Bind
    ... And it requires an additional filter to filter ... : packet fragments. ... The website owner's email address is not functional either. ...
    (microsoft.public.vb.general.discussion)