Is NAT can provide some kind of protection?
jbates at brightok.net
Wed Jan 12 14:18:56 CST 2011
On 1/12/2011 1:35 PM, Owen DeLong wrote:
> The corp IT guy is delusional. The solution to the routing disconnect
> is map+encap or tunnels. Many exploits now take advantage of these
> technologies to use a system compromised through point-click-pwn3d to
> provide a route into the rest of the network. If you allow outbound
> access to TCP/80, TCP/443, or TCP/22, then, it is trivial to create
> an inbound path to your network, NAT or no.
This presumes the inside network is already compromised. In such a case,
a stateful/non-proxy firewall would also be subject to such a thing.
This is not what PAT prevents that a stateful firewall doesn't.
> The argument everyone is making is that a stateful firewall without
> mangling the headers is just as secure (and just as insecure) as one
> with PAT.
Except that the routing isolation means that it is not just as secure.
It has one extra vulnerability over NAT.
> Both can and are trivially compromised.
Agreed that there are still ways around them. Anyone relying on a single
mechanism for security will often find their security to be inefficient.
> As to the PAT scenario only exposing a single port on a single host,
> not entirely accurate, either. I have seen errant mappings which
> exposed much more in a single mapping command on some systems.
On a standard port redirect, I'd be interested to hear the specifics.
However, as my IT guy points out, he doesn't do port or 1-1 redirects
> Then there are the NAT Traversal mechanisms which are necessary to
> make things function but can also be exploited.
Things don't function through his firewall. He likes breakage.
> The list of problems created by PAT goes on and on.
PAT creates a lot of issues. However, for some environments, what it
breaks are perfectly acceptable. Utilizing PAT in home routers and
facilities that have a more open use of technology, would be crippling
the protocol needlessly.
> I've seen PAT bugs that exposed multiple hosts. This is false sense
> of security.
> Paraphrased: A bank vault with a screen door is more secure than a
> bank vault without a screen door.
> Pay no attention to the fact that the bank vault was, in this case,
> built with a skylight.
If you installed a skylight, that's your own fault. Nowhere have I said,
PAT is the ultimate in security and forget everything else. I've said
the opposite. PAT has it's uses and does provide certain safeguards. It
is one small piece in a huge arsenal of security mechanisms implemented
in a network. The entire edge firewall system is only a small piece in
network security. If you strictly depend on the edge firewall for
security, you may someday learn the error of doing so. Many companies have.
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