Isle of Wight computer help

Home |  Contact |  Case studies |  Computer help |  Links |  Feedback |  Sitemap | 


How to temporarily disable your Linux firewall.
This will disable your netfilter based firewall (eg. shorewall) until you reboot.

Used during troubleshooting to eliminate/narrow-down problems caused by the firewall

WARNING - after running this, your firewall will be wide open until you reboot.

You need to be root - open up a terminal and type su <enter>, then your root password and <enter> again.
The prompt should change from $ to #

Install iptables - type "urpmi iptables"

Type or copy/paste the following lines at the command line:
iptables -F
iptables -t nat -F

iptables -P INPUT  ACCEPT
iptables -P FORWARD ACCEPT
iptables -P OUTPUT ACCEPT


Then check with:
iptables -nvL
iptables -nvL -t nat

You should get a list of empty tables, something like:
(there will probably be more entries - the main thing is; INPUT, FORWARD, OUTPUT, PREROUTING and POSTROUTING chains should all say 'policy ACCEPT')

Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination

Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination


Please pass on your comments for improvements, mistakes or omissions to me - work in progress.
Chris
linux@iwpcs.co.uk