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Re: Roach Motel For Packets...



On Sat, 29 Sep 2001, Peter Billson wrote:

>   I have a Linux router with two connections from different service
> providers (eth0 and eth1) coming in and want to route all traffic to go
> out eth2. Eth0 is the router's default gateway
> 
>   I assigned eth2 two ips (eth2=192.168.0.1 and eth2:0=10.0.0.1)The
> (important) routes are set to
> 
>  Network    gateway    netmask        iface
> 192.168.0.0   *       255.255.255.0    eth2
> 10.0.0.1      *       255.255.255.0    eth2
> (eth1 net)    *       255.255.255.0    eth1
> default    (eth0 ip)   0.0.0.0         eth0
> 
>   Ips have been changed to protect the innocent. All ips are really in
> the public IP space.
> 
>   I am *not* trying to load balance, do BGP or anything like that. I
> basically want the boxen on the network to respond to packets coming
> from either network.
> 
>   I'm using IPChains to get this all working nice.

Show us.

>   If I ping any of the IPs serviced by eth0 (remotely or locally)
> everything works fine. I can ping eth0, eth2 or any of the boxes on the
> network.
> 
>   From the router I can ping eth0, eth1, eth2, and IPs that should be
> serviced by eth1 on the network and I can ping the provider going out
> eth1.
> 
>   From the local network I can ping any other machine and *any* IP on
> the router.
> 
>   But if I try to ping eth1, or any of the IPs serviced by eth1, from a
> remote machine the packets come into the router and disappear. They do
> not get DENYed, ACCEPTed or FORWARDed by IPChains on any interface. The
> rules relating to eth0 and eth1 are identical.

I am not sure if I understand this exactly. It may help to have more
information.

I have a feeling your replies are being sent out but are being firewalled
by another router, since they appear to have a source address that doesn't
belong to its network (i.e. address spoofing, SMURF attack).

  Jeremy C. Reed
echo 'G014AE824B0-07CC?/JJFFFI?D64CB>D=3C427=>;>6HI2><J' |
tr /-_ :\ Sc-y./ | sed swxw`uname`w



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