server question

[dave2k]

my apache web server sits behind a router, meaning the router has to be configured before my site can be accessed from the outside world. what i don't unserstand is that there are server programs, such as msn messenger on my pc, which accept incomming connections. how do these connections connect if my IP address is private?

if so is it possible for me to create a simple http server so people on outside world can connect to my pc WITHOUT configuring my router?

[MikeAThon]

my apache web server sits behind a router, meaning the router has to be configured before my site can be accessed from the outside world. ....

[ I]s it possible for me to create a simple http server so people on outside world can connect to my pc WITHOUT configuring my router?
No. You must configure your router in order to accept incoming connections. There is no way around this.

what i don't unserstand is that there are server programs, such as msn messenger on my pc, which accept incomming connections. how do these connections connect if my IP address is private?
There are many different ways of accomplishing this. First, many programs that appear to accept incoming connections actually are not. They are communicating via a third server, sometimes called a rendezvous server.

For those programs that actually accept incoming connections, most are using UPnP to configure the router automatically.

Finally, a few are using sophisticated "hole punching" techniques. Search in these forums for "hole punching" and you will find a few links to outside sites that give full explanations.

Mike

[alex_gusev]

there was some article about Skype's technique of getting around firewalls, don't remember where I've seen it, but as MikeAThon posted, it uses some kind of rendezvouz server ans actually causes firewall to think that incoming packages are valid

[dave2k]

i have read up some more and i think most use a third server. i assume this means all info passes through this server? which means say i wanted to transfer a file, it would have to be uploaded to the server and downloaded to the other client pc?

[alex_gusev]

nice research was done here (http://www1.cs.columbia.edu/%7Elibrary/TR-repository/reports/reports-2004/cucs-039-04.pdf)