I need to set up a firewall using slackware.

Rhe three nics are loaded nicely with
their respective modules.

ifconfig shows eth0 eth1 eth2

my problems starts when im trying to test connectivity by pinging

from my xp laptop to the slackware box and backwards.

The logical outcome promts that when all the pci cards are installed 2 of them do not
receive or ping other hosts. When i remove one of the pci network cards
everythinks works fine . Now to avoid confusion all the 3 cards load different
modules
eth0 sis900 sis
eth1 e100 intel
eth2 dmfe tulip

In the end of dmesg the following lines appear which i think are relevant :

ip_local_deliver: bad skb: PRE_ROUTING LOCAL_IN LOCAL_OUT POST_ROUTING
skb: pf=2 (unwned) dev=lo len =112
PROTO=1 192.168.0.1:0 192.168.0.1:0 L=112 S=0xC0 I =33654 F=0x0000 T=64

Thanks in advance

I found a similar thread regarding my issue which is when 3 nics are instralled cannot

ping each other some how .

it is here
thread

and here is a interesting reply.

reply


The reply reports that pinging each other host is not important since the kernel
forwords the packet to the first ethernet card. Additionaly it mentionts that
if i set a firewall ( which is my main objective ) then iptables
will to the job , to clarify packets destinations and arrivals.

Good news problem solved .

For those who have 3 nics and some of them cannot ping each other
for no reason should follow

this thread
here

in brief if

eth0 dhcd assigned
eth1 192.168.0.1
eth2 should be 192.168.1.1 MY MISTAKE WAS TO place eth2 under the same subnet as eth1

therefore the other side of eth1 should have as default gateway 192.168.0.1
and for eth2 the default gateway should be 192.168.1.1

last detail for you to reach 192.168.1.2 host which is the other side of the eth2
(you propably have assigned different ips)

type

route add 192.168.1.2 dev eth2

therefore eth2 is the default nic for the 192.168.1.2 ip
All the packets for the 192.168.1.2 will pass through eth2

Hope this might help