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Old 04-22-2006, 08:35 AM   #1
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Registered: Apr 2006
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problem with command "modprobe iptables" in the debian server

Hi! I want to make a home network. I have an old pentium 200 with 64 Mb Ram and 4 Giga of hard disk with two realtek network cards with an old version of debian in text form with only the essentials installed in it. Beside it I have three other computers (with os windows installed)linked to the debian server with a cheap and simple switch. Below is listed all files that I configured :

auto eth0
iface eth0 inet dhcp

auto eth1
iface eth1 inet static


/sbin/iptables -F
/sbin/iptables -t nat -F
/sbin/iptables -t mangle -F
/sbin/iptables -X

/sbin/iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
/sbin/iptables -A INPUT -m state --state NEW -i ! eth0 -j ACCEPT
/sbin/iptables -P INPUT DROP

/sbin/iptables -A FORWARD -i eth0 -o eth1 -m state --state ESTABLISHED,RELATED -j ACCEPT
/sbin/iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT

/sbin/iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

/sbin/iptables -A FORWARD -i eth0 -o eth0 -j REJECT

/etc/init.d/gateway :

#! /bin/sh

# If no rules, do nothing.
[ -f /etc/gateway.rules ] || exit 0

case "$1" in
echo -n "Turning on packet filtering:"
/sbin/modprobe iptable_nat
/sbin/modprobe ipt_MASQUERADE
/sbin/ipchains-restore < /etc/ipchains.rules || exit 1

echo 1 > /proc/sys/net/ipv4/ip_forward
echo "1" > /proc/sys/net/ipv4/ip_dynaddr

echo "."
echo -n "Turning off packet filtering:"
echo 0 > /proc/sys/net/ipv4/ip_forward

/sbin/ipchains -F
/sbin/ipchains -X
/sbin/ipchains -P input ACCEPT
/sbin/ipchains -P output ACCEPT
/sbin/ipchains -P forward ACCEPT
echo "."
echo "Usage: /etc/init.d/gateway {start|stop}"
exit 1

exit 0

I connected my server to my adsl provider using 'pppoeconf' (in /usr/sbin)

# cd /usr/sbin
# pppoeconf

and finally I was able to browse with my server (text form as I don't have the graphics installed - using ping command ).

I did the usual configurations with the internal computers (with os windows)providing them with the static IP and primary and secondary DNS Server as given by my ISP.

I conclude this long and boring letter indicating the problems that I am having :

a)my internal computers are not able to see my server
b)using command at my sever console like:

bash# modprobe ip_tables
bash# lsmod | grep ip_tables

gives me error like modprobe iptables not found!!!!
c)using make menuconfig the computer says that they are commands not defined.

I thank you for reading it all and I hope that somebody will be able to resolve my problems.

Last edited by peter_robb; 04-22-2006 at 09:51 AM.
Old 04-22-2006, 09:49 AM   #2
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Registered: Feb 2002
Location: Szczecin, Poland
Distribution: Gentoo, Debian
Posts: 2,458

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In your /etc/init.d/gateway file you make quite a few references to /sbin/ipchains.. They should be iptables.. Especially when loading the ruleset..

Start with ifconfig to see which interfaces you have..
Then dmesg to see which interface was given to the pppoe connection..
Then do route -n to see which gateway is used..
Then do iptables-save to list the currently loaded iptables rules..
and lsmod to show the currently loaded modules..

Then adjust your rules to use the interface the gateway is on as the outgoing interface.
You don't generally need to manually load iptables/netfilter modules as they load when the rule is loaded. Some do need manual loading, eg ftp and irc modules.

One rule states FORWARD -i eth0 -o eth0 -j REJECT which does nothing..
The FORWARD rules do nothing useful as the POLICY is ACCEPT anyway and no rules DROP anything..

I'd suggest a read of the iptables tutorial..

Last edited by peter_robb; 04-22-2006 at 10:08 AM.


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