FAQ Database Discussion Community

So many persistent connections to the server. Is that the right way?

I would like to understand networking services with a large user base a bit better so that I know how to approach a project I am busy with. The following statements that I make may be incorrect but they still lead to the question that I want to ask... Please...

Are there security measures against udp hole punching? [closed]

I want to establish an UDP communication between two peers, say Alice and Bob. Alice is behind a port restricted cone NAT (so that the same internal port gets mapped to the same external port even if the destination is changed), while Bob is behind a symmetric NAT (which means...

For how long a router keeps records in the NAT and can they be reused forwarding requests from other hosts?

There is an answer explaining in simple terms how a router works translating requests from the local network to outside and back (http://superuser.com/questions/105838/how-does-router-know-where-to-forward-packet) what is not clear - for how long a record in the NAT is kept? For example, if I send a UDP request to and my...

Access webserver that's behind a symmetric NAT

How can I access a webserver if both the webserver and the client are behind symmetric NATs? I thought about using a second server as an HTTP proxy/relay but I'm not sure if this is possible.

Is there a way to access a websever behind NAT?

I am trying to access a web server behind NAT. The challenge is: because there could be several web servers coexist, router registration based on port is not a feasible solution here. I apologize this looks more like general question, because I really don't know where to start after reading...

I can't start the docker service with iptables error

This is my linux version information CentOS Linux release 7.0.1406 (Core), and my iptables version is v1.4.21 After I installed docker using the command yum install docker, I am trying to start docker with the command service docker start, but I can't start docker. The error message received is [[email protected]

OData not working behind router with port address translation (port forwarding)

I have two applications hosted on different computers : An OData web site APP1 on PC1 A basic MVC application APP2 on PC2 My router (my.server.com) is configured to forward following request : *:10080 to PC1:80 *:20080 to PC2:80 I used Microsoft.OData.Client library to generate OData context and use it...

If app A listens to the same private port previously used by app B, will app A get app B's public port number?

If one application listens to the same private port number previously used by another application on that computer, will the more recent app get the same public port number as the less recent app? Application A and Application B both use non-multicast UDP. They both run on a computer that...

How do I access a ServerSocket behind an NAT router?

Goal I'm making a chat application for android and am currently testing with 2 phones which must eventually work for a few thousand users. Problem I get a ConnectionException saying "Connection refused" whenever the 2 phones try connecting to each other via sockets. Current Design Each phone starts a ServerSocket,...