OK, so I see that your port (1707) is registered with IANA, so you could do
it by opening this port, although other applications could get a surprise if
they are allocated this port by the OS. Presumably you're broadcasting in
order to find a licensing server? As I recall, you don't need to open a
firewall exception if you don't bind your UDP socket to a particular port
number - the firewall will then set up a short-duration dynamic rule to
allow responses. If your licensing server then connects back to the add-in
over TCP (i.e. the add-in implements a TCP listener), then you do need the
firewall exception.

However, I think this is a poor design: you should have the licensing server
respond with a yes/no answer in a UDP packet sent to the client, or if you
need a longer conversation than will fit in a single UDP packet, have the
licensing server respond to the client with its address, then have the
client connect to the server over TCP (the server listening for connections)
to proceed with the licensing handshake. Outbound connection requests are
not filtered by Windows Firewall.

UDP gets a bit of a poor reputation, which isn't really deserved - for small
amounts of data, where there won't be more than one packet's worth of data
in response, it's fine. DNS is perfectly happy with UDP although it supports
both for larger responses. Kerberos likewise supports both; you are supposed
to use UDP for the initial ticket request. In LAN environments you can use a
payload of up to around 1400 bytes (to allow for VPNs) - any more and you
risk packet loss due to fragmentation.

If the client is broadcasting to find a licensing server, you necessarily
require that the licensing server is present on the same subnet as the
clients. This might be a problem for some enterprises. Others may have
firewalls or NATs in between different parts of their networks; in the case
of the NAT the server will not see the client's true IP address and will be
unable to connect back to the client.

I realise this has drifted a long way from WiX, but I felt it was still
useful to have others' input.

-- 
Mike Dimmick
(maintainer of a UDP-based thin-client application server which really ought
to be using TCP now that messages regularly exceed 500 bytes)

-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of David Thielen
Sent: 16 January 2007 22:06
To: Tony Hoyle; wix-users@lists.sourceforge.net
Subject: Re: [WiX-users] Set firewall exception

Our copy protection is a UDP broadcast and a TCP reply to limit the
totally number of AddIns in use to what is licensed.

So we definitely want that port opened no matter what :)



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