[X4U] Airport Express

[David Ledger]

On holiday recently we were in an apartment that has a free wired 
Internet connection. Because it's on a small island traffic is 
expensive and there are some things are filtered to try to keep the 
traffic down.

I wanted my wife's iPhone, my SIMless iPhone and my HP mini NetBook 
to be able to use the connection so I took my Airport Express with 
me. Before going I set it up in Bridge Mode, but when I arrived I 
could make a connection *to* it but not connect to the Internet 
*through* it. The Windows 7 in the NetBook acknowledged it was 
'Connected' but had 'No Internet access'. This may be due to those 
local restrictions, but I don't know Windows well enough to be sure 
what that message really means. Any further information on why I 
should not be able to connect through an Airport Express would be 
welcome.

I then re-configured the Airport Express using the Windows version of 
the Utility. By setting it to create a new network I could make it 
work as required, but I kept getting errors from the Airport Utility 
complaining of double NAT. The error meant that the Utility would not 
save the configuration file so I left it like that for the duration. 
Before leaving I allowed Airport Utility to 'fix' the problem. It did 
so by setting the Airport Express to Bridge Mode, which, as before, 
didn't work.

Any thoughts would be welcome.

Also, why is double NAT seen to be a problem? I've worked in a 
financial institution where to implement the required security some 
routes were NATed at least six times.

I've been running and involved with industrial networks since 1984 so 
I do understand how things *can* work if allowed to.

David


-- 
David Ledger - Freelance Unix Sysadmin in the UK.
david.ledger at ivdcs.co.uk
www.ivdcs.co.uk