testing firewall

[James Gray]

On 06/07/2008, at 5:09 AM, Jim Douglas wrote:

> The Firewall Builder install said it was successful, my System  
> Services does not show the Firewall Builder so I can't stop/start  
> it.  It configured IPTables, IPTables does not show either under  
> System Services.
>
> How can I test my Firewall?
>
> Jim

sudo iptables -L

...will show you what rules are active in the INPUT/OUTPUT/FORWARD/etc  
tables.  To see a specific table (such as pre/post-route and mangle)  
use this:

sudo iptables -L -t mangle

Assuming you added some log rules, you should see the rule hits  
(rejects?) in /var/log/messages and/or /var/log/kern.log.

If you're asking for a basic smoke-test of your firewall rules, try  
Gibson Research's "Shields Up!" service at https://www.grc.com/. I'm  
not a huge fan of Steve Gibson, but his "Shields Up!" is a reasonable  
smoke test for critical services (ports 0-1055).  Why port 1055?!?  I  
have NFI as it is an unprivileged port....but there you go; Steve  
Gibson has his own take on these sort of things.

HTH,

James