"Sylvain Gitta" <[EMAIL PROTECTED]> writes
>What about backdoor issues?
>>From what I understand, with packet filters, stateful or not, a trojan
>horse could open a connection to the outside world on a given port
>(if it's permitted of course), and establish contact with the cracker's
>system.
>
>That would be less easy to do with application gateways, for which
>specific processes should be implemented.
For the same set of rules, either an application proxy or a stateful
filter cannot prevent such an attack. It might be slightly easier to
stage such an attack with a stateful packet filter, since many
installations permit all services outbound. The only way to prevent
this type of attack would be to deny all outbound services.
Smoot Carl-Mitchell
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