Subject: RE: traceroute - again
From: Jim Gribbin (jewelrysupplier@gci.net)
Date: Wed Jan 29 2003 - 11:21:27 AKST
Is this ICMP Echo-Reply something commonly filtered (blocked)out by
router/firewalls such as the Linksys routers, or is it a function of the
ISP?
I ask this because I notice that I have to use the '-I' switch at work
too where I am behind a Linksys router on a GCI DSL modem.
Jim Gribbin
On Wed, 2003-01-29 at 09:03, Leif Sawyer wrote:
> PING : Uses ICMP Echo, ICMP Echo-Reply to establish host awareness
>
> TRACEROUTE: Uses UDP port 33434 as a probe (because 33434 is usually
> not 'listening' for connections
> as well as ICMP Timeout.
>
> If you don't have ICMP Timeouts enabled on your firewall (as well as udp
> port 33434), traceroute
> will not work for you..
>
>
>
> > -----Original Message-----
> > From: Jim Gribbin [mailto:jgribbin@alaska.net]
> > Sent: Monday, January 27, 2003 11:23 PM
> > To: AKLUG
> > Subject: traceroute - again
> >
> >
> >
> > I got traceroute to work, still don't quite understand.
> >
> > I used traceroute with '-I' which tell it to use ICMP ECHO instead of
> > UDP datagrams. I don't know enough (yet) to know the difference.
> >
> > BTW - ICMP is specifically allowed on my router by default, it can be
> > turned off.
> >
> > Jim Gribbin
> >
> >
> >
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> >
>
>
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This archive was generated by hypermail 2a23 : Wed Jan 29 2003 - 11:21:03 AKST