[LARTC] I need some advice.

[Arthur van Leeuwen arthurvl@sci.kun.nl]

<PRE>On Fri, 26 Jan 2001, billy wrote:

&gt;<i> Thanks fore your answer
</I>
My pleasure.

[snip]

&gt;<i> &gt; &gt; if there are some problems or recomandations I must have to take.
</I>&gt;<i> &gt;
</I>&gt;<i> &gt; NAT has a bit of a problem with certain protocols such as FTP. These are
</I>&gt;<i> &gt; mostly handled by the kernel, but there may be cases with new or custom
</I>&gt;<i> &gt; protocols that are not handled yet. You ought to be aware of that.
</I>&gt;<i> &gt; Furthermore, IPsec AH-mode does not work with NAT. IPsec ESP-mode does,
</I>&gt;<i> &gt; fortunately.
</I>
&gt;<i> Yes I new about the NAT problem, now what about masquerading?
</I>
Masquerading is NAT with port-translation thrown in. This enables multiple
IP addresses to be mapped to a single IP address. In 2.4 and the netfilter
and iptables documentation (at <A HREF="http://netfilter.kernelnotes.org/">http://netfilter.kernelnotes.org/</A>)
masquerading is also called NAPT, Network Address and Port Translation.

&gt;<i> I can't find any diference, but there must be, or there the same thing?
</I>&gt;<i> does masquerading have the same problem? I think so.
</I>
Yes, masquerading has the same problems.

&gt;<i> know what do you refer or meen with IPsec AH-mode and IPsec ESP-mode?
</I>
Look at the documentation for FreeS/WAN at <A HREF="http://www.freeswan.org/">http://www.freeswan.org/</A>

IPsec is a protocol to do encryption and authentication of packets at the
IP-level. IPsec AH-mode provides only authentication, but authenticates
packet headers as well as their payload. This directly conflicts with NAT,
as NAT changes the packet headers. IPsec ESP-mode provides authentication as
well as encryption, but does not authenticate the outer packet's headers,
and therefore can be used over NAT-ed conections.

Doei, Arthur.

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</PRE>