nat

I'm attempting to access a SQL Server which is exposed through an IP NAT mapping. All the ports are open. I don't know the details of the NAT, if it's relevant, since that's somewhere else in the company hidden in a pile of red tape. Here's what I figured out. When you attempt to access a named instance of SQL Server, the client asks what port the named instance is running on. If I RDP into the SQL Server I can use netstat to find out the port of that instance and can successfully connect through the firewall. However, connecting via the instance name doesn't work. My guess is that the server

I have 2 ssh servers behind a nat firewall at a location that changes its wan IP every day. They are always at the same wan IP address on a given time but on different ports. I am connecting to server A this way: ssh -p 22001 karl@x1.example.com and to server B: ssh -p 22002 karl@x2.example.com So I get 2 different host keys for the same IP, and also when the IP changes even a different IP for the same host. I have to go on deleting over and over the other key or the old key (in case of IP change) in the known_hosts file. I am hesitating to turn the key verification off, because this would be

I'm trying to generate an SSH server in a machine behind a router. First I tried to bind the SSH to my public IP address: ssh -R 10002:localhost:22 <ip_address> Then I'm prompted with a password request, however my username password doesn't seem to work. Obviously I know my username password, so it seems to me that it's trying to authenticate in another computer under the same network. Any suggestions how to fix this? It would also help me any alternative on how to create an SSH server behind a Router when you don't have access to the Router. The ports in iptables are all open. UPDATE As

I have been reading a lot about different NAT traversal techniques, but I am still a little unclear about how it works. If I open a TCP port on a client machine and send a request to some arbitrary nonexistent server (which won't respond), my client NAT will now have an open channel, correct? Can I then use another (unknown) computer at a different IP address to access that client port if I know both the public and private IP of the client as well as the port number? Or will my NAT check where my server packet is coming from and block it since it is not from the same IP address as the original

It appears to me that newer Android devices run behind a NAT, where the local address is an internal carrier or LAN address and the public address is the router or carrier assigned external address. Nevertheless, newer phones don't return the same address using the NetworkInterface as when accessing an IP detection service. Therefore, connecting via direct P2P SocketChannels inherently fails. Are there any common workarounds to this problem designed for the Android platform? Can anyone clarify what is causing this NAT-like security issue? Any links to Java NAT traversal tutorials or examples (

Is there any way to use UPnP for NAT traversal on Android with a 3G/4G connection, and if so, is it carrier dependent? No, for the time being thee is no way to do that, for the simple reason that the mobile carriers don't use residential-class NATs - what they have is "Carrier-Grade NATs" CGN, see here http://en.wikipedia.org/wiki/Carrier-grade_NAT , and these devices have very different port allocation and management mechanisms from the residential gateways. See the Carrier-Grade NAT (CGN) related documents in this collection: http://www.scribd.com/collections/3292450/P2P PS there currently

We want to establish TCP/IP connection between two android devices. For now we thought that it would be simpler if we make the connection device to device. So there is no server that is between the two phones. Most of the time (if not always) one has no real IP address (NAT and so on). Is this a problem for creating a TCP socket? I didn't manage to find any exact information for this. Any advice and opinion will be highly appreciated. Thanks Is this a problem for creating a TCP socket? Answer is no, it does not make it impossible (unless NAT's have an unpredictable way of mapping IP addresses)