Firewall Wizards mailing list archives
Re: Proxy and Stateful together ??
From: Bennett Todd <bet () rahul net>
Date: Mon, 18 Nov 2002 11:21:49 -0500
2002-11-18-10:45:14 R. DuFresne:
On Mon, 18 Nov 2002, Bennett Todd wrote: [ on running snort on a bastion firewall ] Though you have packets traversing two rounds of 'filtering/inspection', making for a DOS perhaps in heavy attack streams, yes? Or am I missing something. My first thought here was as you mention, seperation of the two inspection produsts, if only to reduce the chances of systems overload.
As you indicate, the two wildlly different handlings of packets --- snort, sniffing the raw stream, attempting some reassembly and URI normalization and whatnot, and doing pattern matching against the results; and the normal bastion host's IP stack, with some stateful packet filtering in front of application level proxies --- offer diversity. If performance is an issue, yes, get more boxes. Take a box so old and slow as to be regarded as completely unusable trash by today's standards --- can't run Windows, can't run Gnome+KDE+Mozilla+blechyuckgag.... Lessay, an old slow pentium with 32MB RAM. Many's the company that ran application proxy firewalls on that grade of gear for a T1, and had no firewall performance problems even when that T1 was loaded. Snort wants a bit more RAM than that, at least if you have the conversation and protscan2 preprocessors enabled, but no more CPU. If you've got better than 100Mbps of connectivity to the internet, and you routinely saturate it, then you'll be needing to have multiple big fast boxes to completely serve that traffic --- but they'll still cost less than one months telecomms charge. While I didn't say so explicitly, I kinda figured that the initial question that launched this thread --- hybrid firewall with stateful packet filtering and application proxies on one box --- was motivated by a small shop, for which a big industrial scale firewall plant wasn't justified. It's easy to fling enough hardware at small problems to prevent performance from being a problem. -Bennett
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Current thread:
- Proxy and Stateful together ?? Jean Caron (Nov 15)
- Re: Proxy and Stateful together ?? Bennett Todd (Nov 16)
- Re: Proxy and Stateful together ?? Paul D. Robertson (Nov 16)
- Re: Proxy and Stateful together ?? Jean Caron (Nov 16)
- Re: Proxy and Stateful together ?? Bennett Todd (Nov 18)
- Re: Proxy and Stateful together ?? R. DuFresne (Nov 18)
- Re: Proxy and Stateful together ?? Bennett Todd (Nov 18)
- Re: Proxy and Stateful together ?? Jean Caron (Nov 18)
- Re: Proxy and Stateful together ?? Bennett Todd (Nov 18)
- Re: Proxy and Stateful together ?? Paul D. Robertson (Nov 16)
- Re: Proxy and Stateful together ?? Bennett Todd (Nov 16)
- Re: Proxy and Stateful together ?? Bennett Todd (Nov 18)
- Re: Proxy and Stateful together ?? OpenBSD Paul D. Robertson (Nov 16)