I've been using ISA 2004 on a box that's been facing the internet since it's was released as a public beta. I've run other firewall "appliances" as well as both m0n0wall and pfSense (pfSense is a variant of m0n0wall optimized for use on standard PC hardware) and I've really found it to have the best featureset. I also read an article on Network Computing or Windows Magazine that put ISA2004 as one of the fastest firewalls, almost achieving "full" 1000Base-TX speeds.
I think ISA's real redemption comes from the hardware that it runs on, standard (sometimes cheap) PC components. If you get a power surge on an Ethernet card (because only in the engineer's dreamworld does the Ethernet cable get it's on surge arrestor) and blow the card, there's a $20 replacement at the local computer store. On the other hand, you have the sleek, integrated units that you have to throw away or RMA if something gets zapped, and you won't be able to troubleshoot it to the same degree you'd be able to troubleshoot an ISA server. Personally, I was able to configure the ISA2004 box to do just about everything, once I understood how the rules worked. I've got setup to demand dial a PPPoE connection, it also handles the site-to-site VPN, which was a PPTP connection at first, but then IPsec after the remote site got a sonicwall Pro 330 (which is no where near as configurable, IMO). The only real issues I've had with it are more related to windows, rather than ISA (compared to a cisco 2600, windows' routing table leaves something to be desired). m0n0wall is a nice package if you're planning to use something like a PC Engines' WRAP or a Soekris single-board computer (WRAPs are limited to about 45Mbps throughput, soekris is substantially more powerful). pfSense was forked from the m0n0wall source and developed specifically to run on standard PC hardware, it's SMP aware so there's a benefit if you need a really fast firewall. PfSense has a lot of features, but I don't think they'll all ever be as mature as the features that ISA has, which has more features than I have explored. I don't know how helpful I've been, but I figured I'd speak up since I've worked with a few different types of firewalls (I work for an ISP). -----Original Message----- From: James Eaton-Lee [mailto:[EMAIL PROTECTED] Sent: Tuesday, November 15, 2005 16:28 To: Marcos Marrero Cc: [email protected] Subject: Re: ISA Server or Firewall Appliance? On Tue, 2005-11-15 at 11:58 -0500, Marcos Marrero wrote: > Hello to all, > > I have a question to see what everyone out there thinks. Here it goes... > > Is it better to have a firewall appliance (Checkpoint, Juniper, etc) or > is ISA server enough to use as a firewall (along with all of the other > options it provides)? > > Of course the ISA server would sit facing the internet, like a firewall > would and it would have to sit on a hardened machine. > > Just want to know what everyone out there thinks about this > configuration or idea? What you have to bear in mind here is that an appliance is, generally, a hardware platform fairly similar to that which you might deploy ISA on top of, with a proprietary operating system (typically based on freebsd, or some other BSD-derived OS). Oftentimes these firewalls will run from flash memory rather than hard disks, but that aside there can be very few differences - I've seen more than one appliance (checkpoint being just one) based around a fairly standard ATX motherboard with an AthlonXP chip! Appliances have advantages in some instances and not in others. Specifically, due to the overhead of running ISA (which is harder to chop down to provide a subset of the capabilities of a simpler package) and a large, general purpose operating system, you'll almost find that an appliance will handle a greater load then ISA on a similar box, particularly if you're doing anything remotely intensive (although with modern hardware you'll frequently hit hardware limitations first). Arguably, due to the dedicated nature of an appliance, it's also securer as there are fewer running services, and there's more operating system hardening and more functionality gutted out of the operating system - less to go wrong, and less to exploit when something does. There are also disadvantages to appliances - they're, generally speaking, not designed to be administered in as comprehensive-a manner as their 'software' counterparts - meaning that when you do need to remove or add something it can be harder. This argument applies equally to adding NICs and, for instance, adding proxying capability. Specific to ISA, ISA is extremely flexible, and you'll probably find is far more capable of being deployed in different roles than, for instance, checkpoint. This is also a mixed blessing (as you don't necessary want ISA providing routing for your internet backbone, even if you can use it for this). It also benefits from domain integration, and (in my opinion), this is one of the most compelling arguments in its favour. You could also argue that if you want separation between different segments of your security strategy, this is a bad thing when compared to a set of checkpoint firewalls. You'll get a different argument on this from everyone (everyone has their favourite firewall), but hopefully that's outlined some of the broader arguments in favour of appliances vs. software firewalls. It's also worth looking (shudder the thought) at 'free' alternatives, if you're doing a comparison - and there are just as many different options here as there are in the commercial world, from the use of an operating system which provides routing/firewalling capability through kernel&userspace tools generally bundled with the OS (such as openbsd with pf, freebsd with ipfw, or linux with iproute2/netfilter) to an 'appliance' based on BSD or linux. The latter choice starts to become more appealing when you bear in mind that plenty of vendors (checkpoint, juniper and borderware being just a few) base their network devices on BSD (and some on linux, like linksys). It's another debate entirely what they add to bog-standard BSD, but the comparison is worth making. m0n0wall, ipcop, smoothwall and redwall are all worth looking at in these situations - m0n0wall being perhaps the most appropriate for deployments you may be looking at. They are worth at least looking at when in the commercial world, license fees are such a large consideration! The only last point I'd make is that I'd be hesitant in deploying ISA in an internet facing role (although I do and have done that before) - but I don't really have a justification for this aside from "it just doesn't feel quite right". Hope that helps! :) - James. > Regards > Marcos Marrero * Banking Officer * Data Security > Lloyds TSB Bank * US Information Technology > _________________________________ > Tel: (305) 347-6421 * Fax (305) 371-8607 > > > > ********************************************************************** > This Email is intended for the exclusive use of the addressee only. > If you are not the intended recipient, you should not use the > contents nor disclose them to any other person and you should > immediately notify the sender and delete the Email. > > Lloyds TSB Bank plc is registered in England and Wales Number: 2065. > Registered office: 25 Gresham Street, London EC2V 7HN. > > ********************************************************************** > > > This email has been scanned for all viruses by the MessageLabs SkyScan > service. > > --------------------------------------------------------------------------- > --------------------------------------------------------------------------- > --------------------------------------------------------------------------- --------------------------------------------------------------------------- --------------------------------------------------------------------------- ---------------------------------------------------------------------------
