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Re: OK, Now I see what the firewall issues are with Cfengine in our envi
Mark . Burgess
Re: OK, Now I see what the firewall issues are with Cfengine in our environment
Thu, 24 Jun 2004 22:40:12 +0200 (MEST)
On 24 Jun, Scott Omar Burch wrote:
> Based on our firewall policy which generally is the following:
> 1) Return traffic from an application is allowed by a rule on a specific
> port through a firewall to a machine on the other side of the firewall.
> When an applications source port changes at random then that becomes a
> serious problem for firewall policy...basically the only way to write a
> rule for Cfengine is allow all ports to talk back to the policy server
> sitting on the other side of the firewall.
> When using simply snoop to analyze a session between the policy server
> and a client the following is observed (the snoop session is on the client).
> 1) The client connects from a random source port to port 5308 on the
> policy server (this is the problem).
> 2) The policy server responds from 5308 to the randomly chosen source
> port (this is not a problem because we allow all traffic from inside
> along the management interface.).
> So to make Cfengine work we would need a firewall rule that allows all
> ports on particular interface to pass through the firewall to the policy
> server. Seems like it wouldn't be to hard to tell cfagent to use a
> specific source port rather than randomly choosing a port number (but
> I'm probably oversimplifying the situation). I don't believe this is
> possible now, but if not any thoughts on changing that aspect of Cfengine?
is there a reason why you can't just allow random tcp ports from a
restricted address range into your firewall? CFservd also has its own
firewall-like features to eliminate unwanted traffic.
I don't know if it is possible to fix the sender port in a tcp
connection. It seems to me that it is not the port number that
matters here, but rather the IP source address of the caller.
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