Date: Thu, 17 Jan 2002 10:15:11 +0100 From: "Reto Trachsel (NetModule)" <reto.trachsel@netmodule.com> To: "'net@freebsd.org'" <net@FreeBSD.ORG> Subject: RE: ICMP Redirect Message-ID: <F58DFF990DB0D411841D000102A7CD70090BFC@tigris.pacific>
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Hi Crist
Hi, i'll describe a little more in detail:
"Router" FreeBSD-4.5-RC Machine, configured as Router with multiple
aliases on a interface
"WinHost" A Client machine with Windows 2000
"BSDHost" A FreeBSD-Current machine
Sysctl settings on Router and BSDHost:
net.inet.ip.redirect: 1 -> Sending ICMP Redirect
net.inet.icmp.drop_redirect: 0 -> Does not drop
net.inet.icmp.log_redirect: 1 -> Logging ICMP Redirect
Problem Cases:
BSDHost/WinHost and Router
The Router send a ICMP Redirect, but not only once, every time a icmp packet
is recived. The BSDHost doesn't add the routing table.
BSDHost/WinHost and Linux or CISCO Router
The Router (Linux/CISCO) send once a ICMP Redirect package. The Client add
the route to his routing table. The client side work well.
Is there a problem with ICMP Redirect on the same interface? Why doesn't
accept the clients the ICMP Redirect?
Regards
Reto Trachsel
-----Original Message-----
From: Crist J . Clark [mailto:cjc@FreeBSD.ORG]
Sent: Donnerstag, 17. Januar 2002 02:18
To: Reto Trachsel (NetModule)
Cc: 'net@freebsd.org'
Subject: Re: ICMP Redirect
On Wed, Jan 16, 2002 at 01:15:54PM +0100, Reto Trachsel (NetModule) wrote:
> Hi All
>
> I have some problems with ICMP Redirect. I'm using a FreeBSD-4.5-RC
machine
> as default Rrouter for our network. If i'm doing a ping to an external
host,
> a ICMP Redirect message is sended by the router-machine, but not only
> once... it is sended every time a ICMP echo-request is detected. The Host
> doesn't enter the route from the ICMP redirect into his table. With other
> Systems (ie RH Linux and CISCO Routers), this will work on this host
> correctly.
I am a little unclear on this. Is "router-machine" the FreeBSD router
in question? What kind of machine is "Host?" Are we trying to get
"router-machine" to stop sending redirects? Or are we trying to get
"Host" to accept and use the redirects?
> Is there a posibility to switch on/off the ICMP redirect? How can i
> configure, which hosts to redirect?
You can turn sending/receiving redirects on and off with sysctl(8),
but not on per-host basis. You could simulate this behavior to some
degree using firewalling.
> I saw the configs for sysctrl, but no way to enable or disable the sending
> of these packets. Du you have an idea?
>
> net.inet.icmp.drop_redirect = 0
A machine will ignore incoming redirects. If you want "Host" to use
the redirects, set this to one.
> net.inet.icmp.log_redirect = 1
This logs the event.
The other sysctl(8) you may be interested in is,
net.inet.ip.redirect
Which controls whether a router sends redirects.
--
Crist J. Clark | cjclark@alum.mit.edu
| cjclark@jhu.edu
http://people.freebsd.org/~cjc/ | cjc@freebsd.org
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