Note: I've released a podcast of this article if you prefer. 

The 20 Year Anniversary of Check Point's founding has a special place in my heart. Mostly because it is how I personally made my career. How I got involved in Information Security. How I, unbeknownst to me at the time, helped a lot of people get into Information Security.

18 years ago, I had no idea what Information Security was. I was a systems administrator working for a contracting agency fresh out of college. I did some odd programming jobs which, quite frankly, I was never that great at, and eventually, an interesting contract: doing tech support for a company out of San Mateo, CA.

The product: Qualix HA, a high availability product for Sun Workstations based on a Veritas product. One of the products we also sold along with it and provided high availability for was a product called Check Point FireWall-1.

That contract turned into a full-time job and eventually, as the other people in the group kept getting hired out to do "professional services" or whatever, I had to learn FireWall-1 the hard way: by supporting customers calling for help without much of a backstop.

Back in those days, Check Point did all of their support out of Israel. SecureKnowledge didn't exist. They had a mailing list, which had a lot of questions asked on it, but not a lot of answers.

On a hidden page on the Qualix website, there was an FireWall-1 FAQ started by one of the developers at Qualix. I started writing entries on it. Eventually, I got permission from Qualix to take the content and put it on my

Qualix became Fulltime Software and got bought by Legato Systems in 1999. Before that happened, I got a job at Nokia in their IP Routing Group--the guys who make the firewall appliances that ran Check Point's firewall. 

PhoneBoy's FireWall-1 FAQ existed for the better part of 8 years as a publicly available resource containing the knowledge I collected about the Check Point products from the mailing lists and my own work with the product as a technical support guy. Obviously a lot of that knowledge also migrated itself into Nokia's Knowledge Base, which I more or less maintained during my tenure there. It also made its way into two books that I published with Addison Wesley (now Pearson Education).

In parallel, I created a moderated mailing list on FireWall-1 in June of 2000, first called FireWall-1 Wizards, then renamed to FireWall-1 Gurus after the folks who own the Firewall Wizards trademark suggested I should change the name. The mailing list lasted for about 9 years.

Around 2003 or so, I started burning out. Technical Support is a difficult job to do long term in general and I had done more than my share. I ended up moving onto other things inside Nokia's Enterprise Solutions or whatever it was back at that time. In 2005, I agreed to let Barry Stiefel take the content on and copy it onto

I kinda thought I was done with Check Point stuff by then, but I was wrong. I kept working with Nokia's Knowledgebase for the Enterprise Solutions group, which had a lot of Check Point content in it. This meant, for me, reading, writing, and re-writing this content. I kept mentoring folks in the TAC when they had issues with Check Point or just general network troubleshooting. I kept supporting other products that were somewhat Information Security related (VPN and Remote Access product as well as Sourcefire on Nokia).

When the Check Point acquisition of Nokia's Security Appliance business was announced, I wasn't sure what to expect: for a platform that I spent 10 years of my life supporting as well as my own career. When it became clearer that I had a home at Check Point, I began to start looking a bit more closely at the Check Point products again.

What I discovered was that the product hadn't changed all that much. Sure, there was NGX, the rise of Secure Platform and Check Point's own appliance offerings, and many refinements along the way, but the fundamentals of the product were basically the same.

But change was happening: I could see it before I was officially part of Check Point as I was told about the new IPS Software Blade in R70. As I started visiting the Check Point headquarters in Tel Aviv, I got to hear in more detail from the people who develop the product. I got to see the changes up close and personal. App Control, URL Filtering, Anti-Bot, the new (and old) SMB products, DLP, appliances, Gaia, I got to see it all before it was released.

Also, Check Point made a couple of key acquisitions prior to Nokia's Security Appliance business: Pointsec, which was a well-known disk encryption solution, and Zone Labs, which made the ZoneAlarm desktop firewall product. Both of which ultimately became part of Check Point's Endpoint Security offering along with the later acquired Liquid Machines to provide Document Security along with Dynasec to provide Compliance solutions to Check Point's overall product portfolio.

It's been a beautiful thing that I'm proud to say I've been a part of since nearly the beginning. And, of course, there is a lot more to come.

Let's face it: the threats to our networks have only gotten more complex, more dangerous. A lot of the fundamental issues in Information Security haven't changed, either. End Users still do unwise things. Companies don't invest enough time or money in doing the basics in security practices like segmentation, user education, changing default passwords, and a whole host of other practices.

The Information Security market has many players. Check Point plays in many spaces with different competitors in different segments but continues to grow and innovate year over year and continues to remain independent and focused on the goal of securing the Internet in a sea of acquisitions by larger, less security focused companies. 

Here's to another 20 years, Check Point. 

It's pretty obvious from looking through the number of 404s I'm seeing in Google's Webmaster tools that a lot of pages still link to old stuff I wrote about Check Point FireWall-1. I'm actually trying to "fix" these 404s now by resurrecting some of the old content.  Not updating it, of course, but at least making the links point to something semi-useful, if historical.

This is one of those articles, obviously not at it's original URL, but the original URLs will point here. What amazes me about this particular article is that it's still relevant today as NAT really hasn't fundamentally changed in the Check Point products for some time. The basic concepts are still the same, too, and other than the implementation details, is probably relevant for other security products, too. 

Bottom line: NAT only works if the firewall is in the path of the communication. How do you know? Follow the bouncing packet, otherwise known as Troubleshooting 101. 

Hit the break to see this old FAQ in all its ASCII network mapped glory.

When implementing address translation, the unspoken assumption is the firewall will always be between the two machines talking to each other. For external machines accessing internal machines, this is a safe assumption. In the case where internal hosts are accessing internal hosts, this is not always the case.

Another important thing to note is that NAT rules are processed in the order they are listed. Once a packet matches a rule in the rulebase, subsequent rules are not processed for that packet. NAT rules are not applied cumulatively.

To demonstrate these principles in action, here is an example network:

Internet Segment (204.32.38.x)
-------------------------------- (
                         (        (
                             |                  |
       Segment A (10.1.x.x)  |                  | Segment B (10.3.x.x)
                             |                  | 

The firewall has two interfaces: and The router has three interfaces:,, and Each interface of the router has a class B netmask (

Let's assume an "Externally" accessible SMTP server is at and it has an external address of (via NAT). There is some other internal SMTP server ( that tries to access the "external" SMTP server via the external address. Assume the following NAT rules:

  Original Translated
No Source Destination Service Source Destination Service
1 Any Any Orig Orig
2 10.x.x.x Any Any Orig Orig tries to initate a connection to Routing will eventually take this packet to the firewall. The packet is accepted by the firewall's security policy and is then processed by NAT. The first rule that matches is rule 1, which translates the destination of the packet from to The "source" of the packet is not changed (rule 1 says not to touch it). The packet will then be routed to, then

When sends its "reply," it will be sent to (the "source" of the connection attempt). The reply is routed to and then directly to is expecting replies from (who it thinks it tried to connect to), not, so they are dropped (as they should be). If a machine on 10.1.x.x were to access, the same thing would happen except the packet would travel one less hop.

What would happen if the rules were reversed (i.e. rule 2 was listed before rule 1)? When tries to access, the packet gets routed to the firewall and passes through the rulebase. NAT then would rewrite the source of the packet to be The destination of the packet would still be (i.e. it does not get translated), but gets routed out the internal interface (or at least it should if you've configured NAT correctly. ;-). The internet router sees this packet and routes it back to the firewall (it's an external address, after all). The packet would ping pong back and forth until the TTL expires.

One reason why you might connect to the translated IP address is because your internal client's DNS server points to it. You can resolve this problem by implementing split-horizon DNS, i.e. different DNS servers for the internal and external networks. An internal DNS server reflects the internal IP address for a host and the external DNS server reflects the externally resolvable IP addresses for the host. Internal clients will use the internal DNS server. You can also put a host entry on the local system pointing at the internal address.

Other than implementing split-horizon DNS, can you get around this problem? There are two methods you can use to get around this problem, which I have documented below.

Put Externally Accessible Hosts on a DMZ

This actually makes more sense from a security standpoint because you can provide more control over access if externally accessible host are all on their own segment. To create a DMZ, you would have to add a third interface to your firewall with a different logical subnet and move the accessible hosts to that subnet.

Internet Segment (204.32.38.x)
-------------------------------- (          DMZ segment (172.31.0.x)
                                   FireWall (
                         (        (
                             |                  |
       Segment A (10.1.x.x)  |                  | Segment B (10.3.x.x)
                             |                  | 

This puts the firewall between the client and the server, thus solving the NAT problem.

The Dual-NAT Trick

The success or failure of this trick is dependent on the OS that you use for your firewall and may even depend on the environment. In most cases, it does not work. When a packet is received in one interface and is routed out that same interface, the OS's TCP/IP stack will instead issue an ICMP Redirect with the system's untranslated IP address. Depending on the circumstances, this connection may either never take place or take a long time to establish. FireWall-1 can't do anything about this. Assuming my trick does work for you, you are effectively doubling the amount of traffic that the connection would generate and add additional, unnecessary load to the firewall. The best way to resolve this problem is to simply not use the translated IP address in the internal network.

In order to insure that the firewall stays between the connection between the two hosts, you will need to create dual NAT rule. The NAT rule will look at both the source and destination of the packet and translate both the source and the destination of the packet. Because the rules are processed in order, the dual NAT rule must come before both your "HIDE" rule and your SMTP server's translation rule as below:

  Original Translated
No. Source Destination Service Source Destination Service
1 10.x.x.x Any Orig
2 Any Any Orig Orig
3 10.x.x.x Any Any Orig Orig

What will this do?

  • All traffic coming from 10.x.x.x that is destined for will get hidden behind (the internal IP address of the firewall) and have a destination of
  • All other traffic coming to will keep the original source and have a destination of
  • All other traffic coming from 10.x.x.x will get hidden behind (the external IP of the firewall) and keep the original destination.

The side effect of this is that for each connection to your "internal" SMTP server using the external IP address, you will see the network connection traverse your internal network twice:

  1. Once between the "server" and the FireWall
  2. Once between the firewall and the "client"

If you have done this and you still can not access the host in question, use a packet sniffer to determine what is going on. In cases where it will not work, the firewall system will send an ICMP redirect to the client pointing them to the internal host using the untranslated address. Since the client is not expecting to see the host's real IP address, the connection will fail. In this case, you will need to disable ICMP redirects on your host system. The only system I know how to do this on is Solaris, and the command is as follows:

   /usr/sbin/ndd -set /dev/ip ip_send_redirects 0

On IPSO, this is done at a per-interface level. If VRRP is running on a particular interface, this is the default behaviour. If you are not running VRRP on a particular interface, then issue the following command if the interface you wish to enable it on is eth-s3p1c0 (add it to /var/etc/rc.local if you wish for this command to be active after a reboot):

   ipsctl -w interface:eth-s3p1c0:family:inet:flags:icmp_no_rdir 1

On NT, you can disable ICMP Redirects with NT Service Pack 5 and later by adding or modifying the following registry entry:


This key should be a DWORD set to 0.

If you know how to do this on other platforms, please contact me so I can update the page.

Optionally, you can also block ICMP Redirects at the firewall:

No. Source Destination Service Action Track Install-On
1 Firewall any icmp-redirect drop   Source

Binding the NATted IP address to the Loopback Interface

The basic idea is to bind the translated IP address to the loopback interface of the server. On Unix machines, you use a command like

   ifconfig lo0:0 up

On NT, you will need to add the MS Loopback interface (which you will need to add to the system) and add the IP address to this interface with a netmask of If packets come into the system for the translated IP address (because, for instance, they did not come to the firewall), the system will respond to packets for this IP address. This method does require slightly more administration since now you must also maintain the NAT on the individual servers as well.

From PhoneBoy Speaks Ep 305: Threat? What Threat?

In sealed court documents accidentally leaked on a US Federal government website, the US government basically admits that there has been no attempted domestic hijackings of any kind in the 12 years since 9/11. Furthermore, at least as of mid-2011, terrorist threat groups present in the Homeland are not known to be actively plotting against civil aviation targets or airports.

It gets better. Jonathan Corbett, the guy who has been challenging the feds on the constitutionality and the effectiveness of the TSA in the courts, was told by the US Justice Department to take down his comments about a sealed document he wasn't allowed to talk about, but the government themselves posted the unredacted version on their site and other sites made it public.

The same is true for Corbett's comments about those documents, the Justice Department asked him to remove from his site, but they apparently forgot to tell Google as it was still in their cache!

This is a clear demonstration of what can happen if confidential data inadvertently leaves your organization. Clearly this unredacted, sealed legal brief should have never been made public. Thankfully, in this case, it was, but surely some folks in the US Government weren't happy with this lapse. Neither would your employer if it's your company's secret plans for world domination that got leaked.

Likewise, if you inadvertently leak information on your own website, or someone else does, even if you can manage to get it taken down, Google takes a while to forget it saw it. The rest of the Internet won't necessarily forget, though. Ever.

So what are your plans for Data Loss Prevention in your organization? Are you even employing any DLP technology? Is it actually catching real incidents of data loss or is everyone going around it? 

I'm not saying DLP is a panacea or 100% effective, but if you're not doing it, then you don't have any idea where your corporate information might end up. 

Sample Link Post

This theme supports link posts, made famous by John Gruber. To use, just add

link: http://url-you-want-linked
to the post’s YAML front matter and you’re done.

If you ran Check Point FireWall-1 on SunOS or Solaris, you probably remember this screen:

This is a screen capture from fwui, the management interface for FireWall-1. Actually FireWall-1 2.0 and 2.1 looked like this too.

Meanwhile if you ran the management interface on Windows, you were presented with something like this:

You could actually run the firewall on Windows NT as of 2.1, though it took until 2.1c until it was reasonably stable.

Actually you could run something that looked like the Windows UI on Solaris with Motif, which Check Point charged extra for. Eventually the Motif and the OpenLook GUI were deprecated and what we now refer to as SmartDashboad only runs on Windows.

And, of course, there are far more GUI clients these days–about a dozen or so if I remember correctly. But then again, the product does so much more today than it did back in the mid 1990s.

And yes, I remember those days quiet fondly.