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Ian Trackman
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 Posted: Sat Apr 17, 2004 10:25 pm Post subject: Sockets over the Internet |
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I have two Delphi 5 programs on a LAN which send simple text messages to
each other using a TServerSocket and a TClientSocket.
I now want to get them to communicate with each other over the Internet. I
get the router's IP address of the server program visually from its own
software and allocate it to the Host property of the client socket, but
nothing happens when I try to connect the two programs.
From reading other postings, it seems that I can't easily get the IP address
of the Internet connection programmatically except from the router's own
specific APIs - or can I ?
I've never tried this before, so can someone please either help me with some
basics or point me to some "how-to for dummies" documentation ?
The router/modem has a firewall and I'm running the server socket program
under XP with its firewall enabled, if that's relevant.
Is there anything in Delphi 8 that would help me ?
Ian
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Ben Hochstrasser
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| Posted: Sat Apr 17, 2004 10:33 pm Post subject: Re: Sockets over the Internet |
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Ian Trackman wrote:
| Quote: | I have two Delphi 5 programs on a LAN which send simple text messages
to each other using a TServerSocket and a TClientSocket.
I now want to get them to communicate with each other over the
Internet.
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You don't need to know the router's address - the IP stack will take care
of all this. What you need is your own and the partner's IP address.
| Quote: | From reading other postings, it seems that I can't easily get the IP
address of the Internet connection programmatically except from the
router's own specific APIs - or can I ?
|
You can. eg http://checkip.dyndns.org/ will tell you your official
(=outside) ip address. Better yet, get yourself a dyndns address and you
don't even have to know your IP.
| Quote: | The router/modem has a firewall and I'm running the server socket
program under XP with its firewall enabled, if that's relevant.
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If that thusly protected system is at the "receiving" end (i.e. it
answers to an incoming connection) then you have to open the firewall for
that specific port. Nothing special has to be made for the initiating
end, the firewall will let answer packets pass.
--
Ben
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Remy Lebeau (TeamB)
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| Posted: Sat Apr 17, 2004 10:38 pm Post subject: Re: Sockets over the Internet |
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"Ian Trackman" <ian (AT) bluechipbridge (DOT) co.uk> wrote
| Quote: | I now want to get them to communicate with each other over
the Internet. I get the router's IP address of the server program
visually from its own software and allocate it to the Host property
of the client socket, but nothing happens when I try to connect
the two programs.
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The fact that you mention a router means that the server program is running
on a private LAN, correct? If so, the router must have port forwarding
enabled in order for traffic from the outside world to reach the machine
that is running the server program.
| Quote: | From reading other postings, it seems that I can't easily get the
IP address of the Internet connection programmatically except
from the router's own specific APIs - or can I ?
|
Assuming you are referring to the server program determining its own public
IP, you can achieve that by simply having the server query an external
source on the Internet, such as http://whatismyip.com or similar service via
HTTP, and then parse the result. As for the client determining the server's
public IP, it won't be able to do that at all unless the router has a public
host name registered for it, then the client can do a DNS lookup. Otherwise
user input is needed instead.
| Quote: | The router/modem has a firewall and I'm running the server
socket program under XP with its firewall enabled, if that's relevant.
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XP's firewall is a piece of junk. You should disable it and get a real
firewall instead.
Gambit
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Ian Trackman
Guest
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| Posted: Sat Apr 17, 2004 11:15 pm Post subject: Re: Sockets over the Internet |
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<The fact that you mention a router means that the server program is running
on a private LAN, correct? If so, the router must have port forwarding
enabled >
That's presumably US Robotic's "port triggering", isn't it ?
< XP's firewall is a piece of junk. You should disable it and get a real
firewall instead. >
I have - I just disabled it in case it was getting in the way.
Ian
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