IP Masquerading problem

IP Masquerading problem

Post by Richard Whitcom » Thu, 04 Jun 1998 04:00:00

the  problem is IP masquerading....

I have read and followed the instructions in the HOWTO on the subject
but it still doesnt work.  Apologies if this is a little long.....

I have Redhat 5.0 with kernel 2.0.33.  It has PPP and IP masquerade
support compiled and the PPP bit works fine.

My linux PC has the following added to the bottom of the
/etc/rc.d/rc.local file (i got these from the HOWTO...):

/sbin/depmod -a
/sbin/modprobe ip_masq_ftp
/sbin/modprobe ip_masq_raudio
/sbin/modprobe ip_masq_irc
/sbin/modprobe ip_masq_quake

/sbin/ipfwadm -F -p deny
/sbin/ipfwadm -F -a m -S -D
/sbin/ipfwadm  -F -a m -S -D

where and .2 are my windows 95 boxes.  The linux PC is

The windows PC is configured as follows under Network card TCP/IP

Gateway =
IP = / subnet
DNS:  enabled
        Host = String   Domain = Home-.net
        DNS search order =
        search order = Home.Net

i have altered my Internet settings to "connect using a LAN..."

on dialing PPP  though and ensureing it works through linux i try to
connect to anything using the win95 box and it doesn work.  just times
out etc.  I have tried connecting using IP number and DNS entry with
same problem.  DNS never looks up and IP number just unable to
connect.  I've tried www and FTP sites.  Also ping doesnt work
"request timed out" although im not sure if this will work as its

If anyone can tell me what im doing wrong and how to get it to work
i;d appreciate it.

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ICQ UIN 1556459

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IP Masquerading problem

Post by Kevin Mart » Thu, 04 Jun 1998 04:00:00

Quote:>I have Redhat 5.0 with kernel 2.0.33.  It has PPP and IP masquerade
>support compiled and the PPP bit works fine.

Okay so far...

Quote:>/sbin/ipfwadm -F -p deny
>/sbin/ipfwadm -F -a m -S -D
>/sbin/ipfwadm  -F -a m -S -D

The only thing I did differently was to drop the /## mask after the -S
addresses and add -P all.  No one has yet stepped up to tell me why
that worked when all the HOWTO's said the syntax you're using is
the right one....  But it did work for me, I'm using it right now. :-)

If you have ppp dialing on demand, just running "ping" from a Windows
DOS box and pointed at your provider should be enough to make the
Linux box dial for you.  That's the fastest way I know to see that it's
working.  (The Windows "ping"s will not come back, but they will
start the dialer.)


IP Masquerading problem

Post by Dan Elio » Thu, 04 Jun 1998 04:00:00

Whoops!! Sorry the file should be /proc/sys/net/ipv4/ip_forwarding ....

See ya - Dan

* dAN eLIOT             * Computers are like air conditioning   *

* P)                    * They work fine until you open         *
*                       * WINDOZE....                           *


1. IP Firewall and IP Masquerading Problems

I have Linux 1.3.36 with IP Firewall and IP Masquerading turned on.

This machine has 20 MB of RAM, 2 Ethernet Cards, and a Cyclades board with
4 dial-ins.  

It acts as a router for the firewall portions of the nets which is on one
ethernet board and on some of the dial-ins.

About every other day and it happens in the middle of the night, the machine
dies.  I didn't get all the informations from the console but the part that
I do have reads:

        Unable to handle kernel null pointer dereference at virtual address
        current -> tss.cr3 = 0010100, %cr3 = 00101000
        *pde = 00102067


        Killing Intrupt Handler

This always seems to happen when no one is on the dial-in and I know no one
is on the 2 IP Net.  Data on the 1st IP Net si from the Internet to other
machines on that network. (ie. news, mail, ftp, web ...  each different

I started out with 12 Megs in the machine and have gone through several
versions of the kernel in the version 1.3.x series.  

I have had this also happen on another set of machines using the 1.2.X set of

Any and all help to solve this problem will be greatly appreciated.

Todd Reese

Todd Reese
Gwinnett Communications Group
Atlanta, GA

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