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ARP responses broken!

DISCUSSION Bingner Sam J. Contractor RSIS 1 participant 1 message Apr 17, 2001

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Bingner Sam J. Contractor RSIS

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****** Forwarded Message Follows *******

Quoted 1 line

To: "'Christopher Friesen'" <[email protected]>, Sampsa Ranta

<[email protected]>

Quoted 68 lines

From: "Bingner Sam J. Contractor RSIS" <[email protected]>
Date: Tue, 17 Apr 2001 18:07:41 -0000

I tested this with kernel version 2.2.18 and arp_filter appeared to be broken... I enabled it for /proc/sys/net/ipv4/conf/all/arp_filter, /proc/sys/net/ipv4/conf/eth0/arp_filter and /proc/sys/net/ipv4/conf/eth1/arp_filter and it did not change the arp behavior at all. I enabled hidden and it worked, is there a know problem with this functionality?

	Sam Bingner
	PACAF CSS/SCHE
	Contractor RSIS
	DSN	315 449-7889
	COMM	808 449-7889

-----Original Message-----
From: Christopher Friesen [mailto:[email protected]]
Sent: Tuesday, April 17, 2001 4:25 AM
To: Sampsa Ranta
Cc: linux-net; linux-kernel
Subject: Re: ARP responses broken!

Quoted 8 lines · Sampsa Ranta

I have two interfaces that share same subnet, I call eth0 194.29.192.37 and eth1 194.29.192.38. I have forwarding turned on, proxy arp is not neighter are redirects.

When I flush local neighbor table in other machine I use to observe the response and ping the router I get response like:

23:38:25.278848 > arp who-has 194.29.192.38 tell 194.29.192.10

(0:50:da:82:ae:9f)

Quoted 1 line

23:38:25.278988 < arp reply 194.29.192.38 is-at 0:1:2:dc:d2:64

(0:50:da:82:ae:9f)

Quoted 1 line

23:38:25.279009 < arp reply 194.29.192.38 is-at 0:1:2:dc:d2:6c

(0:50:da:82:ae:9f)

Quoted 4 lines

The second one is the valid one, but both interfaces seem to answer to the

broadcasted packet with their own ARP addresses.

This is the default Linux behaviour. It can be turned off by running the following command as root:

echo 1 > /proc/sys/net/ipv4/conf/all/arp_filter

This ensures that interfaces will only respond to arp requests for IP addresses
which are configured as belonging to that particular interface.

Chris

Signature · 10 lines
Chris Friesen                    | MailStop: 043/33/F10  
Nortel Networks                  | work: (613) 765-0557
3500 Carling Avenue              | fax:  (613) 765-2986
Nepean, ON K2H 8E9 Canada        | email: [email protected]
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