Re: Stopping the Shorewall firewall stops my Internet connection

[Mihira Fernando <mihiratheace@gmail.com>]

On 03/04/2011 09:38 AM, Jason Hsu wrote:
> My setup:
> Modem ->  Firewall/server computer ->  Ethernet switch ->  Main computer
>
> The firewall/server computer has Shorewall (firewall), DNSMasq, DHCP3 Server, and SSH.
>
> I'm trying to troubleshoot why I'm unable to connect to my network from another location by using SSH.  But that's not the subject of this post.  This problem is what led me to try stopping the Shorewall firewall.
>
> When I stop the Shorewall firewall, I'm unable to connect to the Internet from the main computer.  However, I'm still able to connect to the Internet from the firewall/server computer.  (I'm able to ping yahoo.com from the firewall/server computer with 0% packet loss.  However, when I try to ping yahoo.com from the main computer, I get 100% packet loss.)
>
> When I start the Shorewall firewall, the main computer's Internet access is restored.
>
> What's going on?  How can turning OFF a firewall block Internet access?  I thought that the purpose of a firewall is to BLOCK connections, not MAKE connections.
How are you stoping shorewall ? if you issue a shorewall stop, it goes 
in to a lockdown mode. You have to issue a shorewall clear to allow all 
traffic.

See : http://www.shorewall.net/starting_and_stopping_shorewall.htm

Mihira.