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On Mon, 25 Jun 2007, Matthew Smart wrote:
> Thanks for the info. That approach seems workable, but complicated, so
> I decided to pull an end run around. I disabled persistence, moved
> sessions into mysql, and am relying on mysql's replication to ensure
> that all servers have the session data.
People keep talking about sessions, but I don't know what
they're doing. I assume the client has a cookie which the
servers recognise (via mysql replication). Presumably the
clients keep hitting different realservers as part of their
session (which I guess has state - eg a shopping cart) and
you have to pass the state info around too. Is this what
you're doing?
> This is probably a naive question, but is there any way for the director
> to identify that a request is coming from a client behind a nat router?
people asked this question a while ago, when users at home
wanted to know whether their ISP could detect that the user
had more than one computer using their connection if they
were coming out of a NAT router. Similarly does Microsoft
know that you have more than one computer installed with
your one license CD.
The short answer is no. From the outside world, it's hard
for the ISP to know how many computers are behind the NAT
router. The long answer is that it should be possible to
watch the ports that the calls are coming from, but it's a
bit of work and no-one seems to do it (and ISP's have given
up on limiting the number of computers you can have at
home).
The machines behind the NAT router call from high ports in
order. So say you're websurfing and you've just fired up the
homecomputer, The first call to VIP:80 will come from
CIP:1025. When that tcpip connection is closed down, the
next call to VIP:80 will come from CIP:1026 etc. These calls
get nat'ed into a similar monotonic series of ports from the
NAT router (with 2.2 linux starting somewhere up near
40,000, but now starting with port 1025). Originally there
was a separate range reserved for each client (I think),
allowing the ISP to watch for multiple clients behind the
nat router. Now I think theirs only one range (to stop this
pattern being observed).
Joe
--
Joseph Mack NA3T EME(B,D), FM05lw North Carolina
jmack (at) wm7d (dot) net - azimuthal equidistant map
generator at http://www.wm7d.net/azproj.shtml
Homepage http://www.austintek.com/ It's GNU/Linux!
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