R: Removing ping/icmp from a network

["Vega - Brunello Ivan" <I.Brunello () vegaspa it>]

I let icmp flowing into internal network, but usually don't like to let outside ping my published servers.

A user could blame on "cannot open web page", but I expect an average network troubleshooter don't rely on ping on 
internet:
after all, I find LOTS of routers in my path to remote sites which drop traceroutes.

Everyone in between is either a script kiddie, or somebody just playing around with ping sweep/basic portscan.


I use icmp on internet just to check whether my ISP has problems going out (as it happens quite frequently :( ), 
thus stopping after the 4th-5th hop.

Idserve (from www.grc.com) is out there, and at worst, you can make some sort of "tcp ping" (e.g. a telnet on port 80).

Ivan

-----Messaggio originale-----
Da: listbounce () securityfocus com [mailto:listbounce () securityfocus com] Per conto di Mark Owen
Inviato: giovedì 27 marzo 2008 18.09
A: Jason
Cc: Ansgar -59cobalt- Wiechers; security-basics () securityfocus com
Oggetto: Re: Removing ping/icmp from a network

On Thu, Mar 27, 2008 at 12:25 PM, Jason <securitux () gmail com> wrote:
*snip*
>  The idea is to limit your Internet footprint to make it as difficult  
> as possible for an attacker. There is no need for a web server to  
> respond to ping from the Internet for example.

It is very critical that your web server responds to ICMP on the Internet.  If you go out of the way and ignore 
essential protocols for IP over a public network, you're just going to create a headache for all of us.

Without ICMP, it is very difficult for us to determine where a problem exists when our clients complain about slow load 
times or inaccessibility to your website.  No ICMP means no basic trace routing, no basic latency checks, and no basic 
error reporting.  So even if the problem is somewhere in our infrastructure that limits or prevents access to your 
site, you're going to get the blame and bad reputation of an unstable server.  If it doesn't respond to ping, and can't 
be traced, its not our fault that our client can't access your site, it's yours.

--
Mark Owen