In UPnP IGD there is 2 services "WANPPPConnection" (or WanIPConnection) and WANIPv6FirewallControl that have methods that look similar:
AddPinhole
Add(Any)PortMapping
Both taking similar arguments (remote/internal host/port, protocol, lease time).
I was wondering, what is the difference between them ? FW control is apparently exclusive to IPv6 while PortMapping seems to allow both v4 and v6, so what is the real difference ? Is there a different behavior ?
A (typical) IPv4 firewall, embedded in an Internet router, has a single IPv4 address on the Internet, on its WAN interface. Devices on the LAN behind it typically use private range addresses. This means that they are not reachable from the Internet.
If a service on a device must be reachable from the Internet, the router must be instructed to forward incoming traffic from one of its ports on its WAN interface, to a port on the LAN device. This is called a "port forwarding," using the NAPT (Network Address and Port Translation) feature of the router.
On IPv6, routers are not provided with a single address on the WAN interface, but a whole prefix. Devices on the LAN all have publicly routeable addresses. There is no need for address and port translation on the router.
The firewall in the router, however, may be configured to block all incoming connections. In this case, the router's firewall must be instructed to pass through traffic to certain ports on certain protocols to certain LAN addresses. This is called a "pinhole" in the UPnP-IGD standard.
Related
I am just experimenting with my phone system and I'm wondering how both endpoints know they are on the same LAN, I have both endpoints breaking out to the cloud phone system with two separate public IP addresses, I've segmented them off from each other with a firewall so they can't see each other however every time I attempt a call between the two end points the call is setup as a peer to peer call and attempts to traverse the local LAN via RTP through the firewall, the firewall blocks the RTP communication and the call has no audio.
I am just wondering how both endpoints are realizing they are behind the same firewall/router since they are both registering with the cloud system from different public IP addresses, I wanted the call to be bridged in the cloud and not traverse the local LAN but somehow both endpoints only attempt the call over the LAN every single time and no idea how they're realising they're on the same LAN.
Anyone else encountered this before?
SIP endpoints don't have to know they are on the same LAN. They just make best use of the IP addresses you provide.
Your INVITE request will provide more insight, but from what you write my guess is that you use public IP addresses for your contact/request URI and local IP addresses in your SDP offer. The local IP addresses are probably routable through the firewall.
With ICE and STUN endpoints may select the best IPs for media traffic - but for that to work the RTP/STUN packets should be able to traverse the firewall in your LAN.
Attempts to communicate directly may mean that LAN uses IPs from public ranges or endpoints a SIP proxy were not smart enough to detect NAT in front of your LAN.
I am looking for a gateway service to transform an IPv6 address to an IPv4. I have a VPS connected to an IPv6 Network but my ISP is on IPv4. So I can't (or don't know how) connect via SSH to my VPS server.
I will appreciate any suggestions?
So you have a client machine on an ipv4-only network and you want to ssh into a machine on an ipv6-only network.
There are a few options.
6to4, works automatically through relays found by internet routing. 6to4 gateway machine must have a public IPv4 address. ipv6 address block is derived from ipv4 address. Relays are sometimes overloaded leading to poor performance.
teredo, works through relays found by internet routing but requires a configured server for connection setup. Several operators run free public teredo servers. Works from behind most NATs. Can be a bit fragile and relays are often overloaded.
configured point to point tunnels either free or paid for. Well-known free operators include Hurricane Electric and gogo6. Free tunnels may have restrictions on allowed protocols and/or poor performance.
I have a question about network connections among computers.
I've made some applications where messages pass through the Internet (via sockets) to make a connection between two devices. However, a strong condition is that two devices must be connected to the same network.
Can anyone give me a trick how to create a communication using sockets between two computers even if they are connected to different netwkorks?
Thank you in advance.
Here is a great tutorial on how to use sockets and general networking
(in java) http://www.thenewboston.org/watch.php?cat=25&number=38
In order to communicate between two diffrent networks over the internet, you will need to do something called port forwarding. What that does is that when your public IP of your network receives a packet with a spesific port number. The router knows where to send that packet to which local IP.
If you dont port forward and receive some data. The router doesent know where to send the packet. Therefore it discards it, which means others wont be able to connect to you.
You will only need to port forward the network with your server (using the example i linked). How you do that is by logging in to your router, and say that a port which the server uses gets forwarded to the IP of the PC hosting the server.
On the other network (client) you will need to change the IP address of which the client shall connect to. That IP address needs to be your public IP of your server's network. You can find that by connecting to the server's network and go to: http://www.whatsmyip.org/ . Keep in mind that public IP addresses may change over time.
Hope this helped!
-Kad
I did not know where to ask this so here it is. This is more of a networking technology question, but any pointers will help.
Suppose, I want to connect to a machine behind multiple gateways. Say I want to connect to my home computer from my office computer. My home computer is behind my ISP's gateway and then behind my wireless router at home. Let's say I know the IP's for all of them. (global IP for my ISP's gateway, local IP for my wireless router within my ISP's n/w and my home machine's local IP within my home). How do I initiate a TCP connection with my home computer ? The standard berkeley socket program only takes one IP and so I can only connect to machines that have global IPs.
Is there a solution ? Am I correct about the berkeley sockets ?
Thanks.
It is entirely possible, with the cooperation of the ISP. The fact that the ISP is giving private addresses should urge you to move to another.
The concept you're after is called DNAT or Port Forwarding.
Let's say you decide on accessing port 1234 on a PC. The address of the PC is Local2. The address of the wireless router (in the network with the ISP) is Local1.
The wireless router must do the translation Local1:X -> Local2:1234
The ISP router must do the translation Public:1234 -> Local1:X
The X means any port can be used.
You only need to know the destination IP address to connect from an application, the gateway address is for the forwarding (routing) of packets which is handled by the OS network stack. However, if the destination is behind NAT, you'll only know the public IP address of the destination's NAT device. Even in this scenario, all you have would be an IP address and you don't really know if there is NAT going on.
If your destination is fixed, you could set up port forwarding on the NAT device (if you control it). Otherwise, you just realized that NAT is pure evil.
In your situation, it appears you want to connect to your home computer. If your wireless device has a public IP address, you can setup port forwarding on that to forward all incoming traffic on a port to a port on your home computer.
I want to connect to a system which is behind a router. I know the public address of the router as well as the private ip (fixed always) of the system. How do i establish socket connection with the private ip?
This is why some people say that they are behind a "firewall", when they are behind a router. The Evil Viruses Of The Internet are not able to exploit any software on a computer behind a router (provided that the router admin didn't configure it in the funny way, for example by enabling DMZ).
You still have some options:
Talk to the router admin and make him forward a port for You
Take the router out and put Your "target" computer where Your router was, or enable DMZ (this only makes sense if there was only one computer behind the router). Warrning: install a firewall on the target computer first!
Turn the socket 180 degrees. Make the computer behind a router establish the connection to the server that has a public IP address
Use something like UPnP, if Your router supports it
Get a dedicated IP address for Your computer and configure router to switch all traffic to this IP address to Your computer (this is similar to DMZ, but would work if You have more than one computer behind the router). Warrning: install a firewall on the target computer first!
Use NAT traversal. There is a very good article on the subject here. Simplified version is that client establishes connection to some remote server. The server can see the opened port number on the client's router and this port is assigned to the client's machine, so it (or some another computer sharing this information) may establish connection to that port and reach the client's application. Warrning: this doesn't work with all routers. Some routers just won't let this happen.
The simplest thing is probably to forward the port from the system you want to connect to through the router.
This is more a question of configuration of the router as opposed to your actual program. If the router isn't configured to forward traffic to the private system, there's no way to force it to connect you - rather, the private system would have to open the connection on its own.
Strictly speaking, the answer to your question is "you can't". You can however enable DNAT (Destination Network Address Translation) on your router. You connect to a certain port on the router, and it forwards the connection to the internal ip. The internal ip (and port) are configured in the router settings and are not known by the connecting client.