Firewall rules to block unwanted protocolls on given ports

[Steven Susbauer]

On 3/19/11 8:05 AM, johhny_at_poland77 wrote:
> Does somebody has an idea, that what kind of iptables/pf rule must i use
> to achieve this?:
> 
> i only want to allow these connections [on the output chain]:
> 
> on port 53 output only allow udp - dns
> on port 80 output only allow tcp - http
> on port 443 output only allow tcp - https
> on port 993 output only allow tcp - imaps
> on port 465 output only allow tcp - smtps
> on port 22 output only allow tcp - ssh
> on port 20-21 output only allow cp - ftp
> on port 989-990 output only allow tcp - ftps
> on port 1194 output only allow udp - OpenVPN
> 
> So that e.g.: OpenVPN on port 443 would be blocked, because only HTTPS
> is allowed on port 443 outbound.
> 
> Any ideas? :\

http://l7-filter.clearfoundation.com/

iptables alone does not categorize traffic based on the application
protocol.

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