Re: Proxies, opensource and the general market: what's wrong with us?

On 04/27/2011 10:52 PM, David Lang wrote:

> however, as proxy firewalls are dieing, new devices with the type of
> checking that proxies do are becoming more common.
> 

I don't think so. No product that I'm aware of has the same "default
deny" on the low level attacks that a proxy has. Again, the recent
"split handshake" problems are a clear example: packet filters "try to
guess" the proper session state, while there is no way to cheat a proxy
into letting a connection in if it's not permitted (up to TCP/UDP, I
mean). Packet-handling tools, be it filters, IDS or something else,
however, are probably "good enough" for the market.

> doing the checking with a proxy listening to a specific port should be
> significantly easier thatn checking for all protocols on all connections
> passing through the devices.
> 

It is, actually, if it's TCP. For what I remember as I wrote some code
in this area, UDP is much more of a nightmare. This is why I say that
proxies are good for some protocols (e.g. http) where you can benefit
from tight controls, but you still need a packet filter underneath for
other protocols: you can't punch a hole in a proxy for a new, unknown
and "essential" protocol.

ciao

- Claudio

-- 

Claudio Telmon
[email protected]
http://www.telmon.org