Firewall and user services that needs open ports

[Les Mikesell]

Callum Lerwick wrote:
> 
> 
>     Why do we need a firewall when you can easily prevent services from
>     being accessed...just stop the service!  Don't bind to the port, and
>     it won't be possible to connect to it.
> 
> 
> Yes, the correct thing to do for local security is use something like 
> selinux to prevent things from binding to interfaces/ports they 
> shouldn't be binding to in the first place.

But what you usually want to control are the ranges of 
source/destination addresses that are permitted.

> Using iptables for this is a 
> completely unsustainable hack. iptables firewalling is for machines that 
> route packets to other machines.

Unsustainable?  But it is what you need to do, not kill functionality 
completely.

> Unfortunately for some reason network devices are exempt from the 
> "everything is a file" architecture thus don't recieve the benefit of 
> the pre-existing filesystem access control architecture.

Yes, this seems like a bizarre design decision in Linux but 
realistically, everything needs network access to be useful at all these 
days and what you need to control is where on the network something 
can/can't connect.

-- 
   Les Mikesell
    lesmikesell at gmail.com