I was developing a system which requires connection between two computers. I decided to connect the two machines together via direct ethernet cable.

My boss didn't like it as there is no firewall in between. The two computer are both connected to separate corporate networks. The cable would essentially bridge these two networks posing security concerns

My boss then decided that we purchase a CISCO firewall just to connect the two machines. I told him why not use windows firewall? Wouldn't that be sufficient? The answer: It's not standard!

Is there any particular standard that demotes Windows Firewall?


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    Cisco isn't "standard" either, so that reply is utterly senseless. There's no such thing as a "standard" firewall. – Michael Hampton Feb 4 '14 at 5:41
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    Nobody got fired for buying Cisco. As in the cautions Exec decisions to buy IBM, there tends to be CYA at stake sometimes. – Fiasco Labs Feb 4 '14 at 6:01
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    I agree with the above comments, but would note that a minority of devs can be trusted with prod firewall configuration, and quite a few sysadmins can't either. If one is lacking skills the brand doesn't matter, so maybe the organisation has Cisco competence and procedures (or the boss is plain clueless)? – ErikE Feb 4 '14 at 6:58
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    Without knowing a lot more about exactly what is going on here it is hard to make a useful judgment. Does one of these systems have HIPAA, PCI-DSS, or top secret data? There might be a good reason why having a strong firewall that isn't built into the OS of the endpoints might be required. – Zoredache Feb 4 '14 at 7:31
  • One advantage to a 3rd party firewall is that you don't need to worry about someone messing with the firewall on the machines at either end. You have a 3rd party involved that neither end can directly control. – Mark Henderson Feb 4 '14 at 20:43

Cisco firewall or not, if I cross-connected two corporate networks without the knowledge and explicit permission of the network owners, I'd be in seriously hot water.

So what you need to do is to get those parties involved. If it's going across their networks, then they need to talk:

Step 1. Establish the owners of both said corporate networks. I mean, find out who is the lead engineer responsible for both of them.

Step 2. Write them both an email explaining what you want to do, and why, asking whether there are any implications for this.

Step 3. Don't do anything without explicit permission from both owners of the other networks.

Step 4. When you have permission from both you can start figuring out how to interconnect them. In actual fact, both network owners should now be in a position to advise you on how it should be done.

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The reason for preferring an ASA (or something) over the windows firewall is extremely unclear in this case.

The appropriate thing to do is to assess whether there is any reason that data should not flow from the node on one side of the (crossover) cable to the node on the other.

The answer is a continuum somewhere between two extremes:

  • Neither computer is internet-connected and both are used by the same people for the same purpose, and they are equally trusted. A firewall of any kind is likely wasted effort in this case.
  • One computer is a publicly accessible node in a DMZ, and another one is connected to a network which processes privileged information. In this case, a firewall is strongly recommended, if the connection must be made at all.

Not knowing where you lie on this continuum makes it very difficult to give a decent answer, but thinking about that might help you arrive at one. It is clear that you lie somewhere in the middle, but you should figure out what it is you want to isolate between the two networks and why it is that they are separate. "I want to isolate connections" is usually not an adequate answer to that question.

As to why one might prefer one type of firewall over another, the best reasons are the existence of a central configuration management infrastructure (or a focus in business expertise) and the need for a particular feature available in one but not the other. Lacking such a reason (and one probably exists), the direction you are being given is likely misguided.

It would be absurd for a public standard to mandate or prohibit the use of certain firewalls by brand name. However, internal standards and contractual standards might well specify such a thing.

The concerns in this case are likely more business than technical.

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There is not a great logical difference between a software firewall and a CISCO firewall, apart from some extra options that you might be able to set on the CISCO device.

Purchasing a CISCO firewall just for a connection between two hosts is a bit overkill. Suggest a different brand, or connect that computer into your firewall and route the traffic through to your computer, instead of directly to your computer.

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  • There are quite a few differences in fact, likely none of which technically matter for the purpose of this question or the stance of the OPs boss. – ErikE Feb 4 '14 at 7:01
  • You're right, I was thinking from the perspective of, if we're just restricting access here, there's not a ton of difference. I'm sure the boss wouldn't notice if an unconfigured firewall sat between the two. – Vasili Syrakis Feb 4 '14 at 7:05
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    I don't believe the Windows Firewall does SPI (stateful packet inspection). Instead, I believe it leverages the IPsec capabilities of Windows and functions as an advanced port filter. – John Homer Feb 4 '14 at 14:55

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