[2211] in linux-net channel archive
firewall setup problems
daemon@ATHENA.MIT.EDU (Robert Lee)
Fri Mar 22 11:55:54 1996
Date: Fri, 22 Mar 1996 10:19:42 +0000
From: leerobert@attmail.com (Robert Lee)
To: linux-net@vger.rutgers.edu
I am trying to create a firewall using ipfwadm on 1.3.66 kernel and having
some problems routing the packets. The following is the setup I have now.
Hub
+------+-+-----+
| | | |
| C B |
PC-C Linux PC-B
Hub: GVC 8 port hub
PC-C: PC with Class C address pointing to Linux-C as the default gateway.
PC-B: PC with Class B address pointing to Linux-B as the default gateway.
Linux-C: NE2000 NIC with Class C address.
Linux-B: NE2000 NIC with Class B address.
Note that Linux-C and Linux-B are single Linux machine with two NE2000 cards.
With the above setup, I thought the following sequence of events could happen:
1. PC-C pings PC-B
2. Linux-C will get the request
3. ipfwadm will allow the request to go through.
4. request is forwarded to Linux-B
5. PC-B sends reply to the ping.
6. Linux-C accepts the reply.
7. ipfwadm will allow the request to go through.
8. reply is forwarded to Linux-B.
9. PC-C get the reply.
What is happening, however, is that from the Linux box, I can ping everybody
(ie: PC-C, PC-B, Linux-C, and Linux-B), from the PC-C, I can only ping Linux-C
,and from the PC-B, I can only ping Linux-B.
Any ideas as to why PC-B cannot contact PC-C ?
Thanks in advance,
Robert S Lee
