I thought it might be helpful to review how to open a hole through Windows Firewall for SQL Server in case anyone else is having this same problem. I ran into this setting up a TFS Farm, but you might run into it if your SQL Server installation for TFS spans multiple computers and you enabled Windows Firewall (as it comes by default).
We have a project where I need 4 pcs from client to RDP in a windows box under my network, and yes firewall rules state no outside world rdp connection under our network. So I need to allow their pcs access through a policy. I know how they work, just not too sure when I create the object for their PCs what IP address I need to use.
Hole punching (or sometimes punch-through) is a technique in computer networking for establishing a direct connection between two parties in which one or both are behind firewalls or behind routers that use network address translation (NAT). To punch a hole, each client connects to an unrestricted third-party server that temporarily stores external and internal address and port information for each client. The server then relays each client's information to the other, and using that information each client tries to establish direct connection; as a result of the connections using valid port numbers, restrictive firewalls or routers accept and forward the incoming packets on each side.
Hole punching does not require any knowledge of the network topology to function. ICMP hole punching, UDP hole punching and TCP hole punching respectively use Internet Control Message, User Datagram and Transmission Control Protocols.
Networked devices with public or globally accessible IP addresses can create connections between one another easily. Clients with private addresses may also easily connect to public servers, as long as the client behind a router or firewall initiates the connection. However, hole punching (or some other form of NAT traversal) is required to establish a direct connection between two clients that both reside behind different firewalls or routers that use network address translation (NAT).
Both clients initiate a connection to an unrestricted server, which notes endpoint and session information including public IP and port along with private IP and port. The firewalls also note the endpoints in order to allow responses from the server to pass back through. The server then sends each client's endpoint and session information to the other client, or peer. Each client tries to connect to its peer through the specified IP address and port that the peer's firewall has opened for the server. The new connection attempt punches a hole in the client's firewall as the endpoint now becomes open to receive a response from its peer. Depending on network conditions, one or both clients might receive a connection request. Successful exchange of an authentication nonce between both clients indicates the completion of a hole punching procedure.
When an outbound connection from a private endpoint passes through a firewall, it receives a public endpoint (public IP address and port number), and the firewall translates traffic between them. Until the connection is closed, the client and server communicate through the public endpoint, and the firewall directs traffic appropriately. Consistent endpoint translation reuses the same public endpoint for a given private endpoint, instead of allocating a new public endpoint for every new connection.
Hairpin translation creates a loopback connection between two of its own private endpoints when it recognizes that the destination endpoint is itself. This functionality is necessary for hole punching only when used within a multiple-layered NAT.
I'm having problem with UDP communication between Linux/Windows machines. I implemented a simple P2P communication protocol over UDP using a relay server. It uses UDP hole punching to eliminate role of server in data transfer. Data transmission between peers and server are on TCP while data is sent on UDP between peers.
I have been struggling to find the appropriate information here, so I'm hoping that you can help me out. I'm looking to setup our Solarwinds Console to perform WMI monitoring of 5 servers at 5 different sites. Ideally this is particularly just simply going to be using WMI to communicate between each. In order to accommodate this, I have to open up the firewalls at each of the sites to allow the specific traffic going through. I have been looking through the documentation for both NPM and SAM, and unfortunately I'm nowhere closer knowing what ports need to leave the clients to the server, and what ports need to leave the server to the clients.
UDP hole punching is not a practice that I would employ -- its an huge security violation. Firewalls exist for a reason, and I would be loathe to post code that intentionally bypassed the NAT that is in-place. (Not that I even have thoughts on how to do it -- don't do it is my answer.)
Although the principle is simple, UDP hole punching is rather complicated in practice if you need to support all sorts of NAT implementations (corporate networks usually are the fun spoilers...). There are a few libraries around like JPunch and JStun if I remember correctly (none for .net that I know of).
UDP hole punching is NOT a security violation in any way, even though the name suggests it is. Once the hole has been punched in the firewall, only connections from the specified client are accepted through it, it isn't like anyone can get in through the hole.
All this does is make both A and B's firewalls think that they have initiated the connection, just as it would let packets from a web server through ONLY if the client had initiated the connection to the web server and the packets were expected.
The detailed explanation of NAT hole punching using Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and for Internet Control Message Protocol (ICMP). This article explains the basic concepts of hole punching.
The above given NAT hole punching method can be used for any of the cases, either both nodes are behind the same NAT or both nodes are behind the different NATs or even if both nodes are behind multiple levels of NATs.
Maybe the only disadvantage of NAT hole punching is that, a publicly reachable server with static ip is always required. An architecture called pwnat was proposed to overcome this, but pwnat only works when either one of the two nodes is not behind a NAT.
We can think of NAT (Network Address Translator) devices as statefulfirewalls with one more really annoying feature: in addition to allthe stateful firewalling stuff, they also alter packets as they gothrough.
I am using Teamviewer 9 and would like to use the VPN option. I installed it all and it works perfectly only if I turn off the Windows firewall on my VPN target. Teamviewer.exe ia already allowed through. Does anyone know what rules I need to setup to let the VPN tunnel through? Both machines are Windows 8.1.
Peer-to-peer software applications are a network administrator's nightmare. In order to be able to exchange packets with their counterpart as directly as possible they use subtle tricks to punch holes in firewalls, which shouldn't actually be letting in packets from the outside world.
Naturally every firewall must also let packets through into the local network - after all the user wants to view websites, read e-mails, etc. The firewall must therefore forward the relevant data packets from outside, to the workstation computer on the LAN. However it only does so, when it is convinced that a packet represents the response to an outgoing data packet. A NAT router therefore keeps tables of which internal computer has communicated with which external computer and which ports the two have used.
Bob's Skype program then punches a hole in its own network firewall: It sends a UDP packet to 22.214.171.124 port 1414. This is discarded by Alice's firewall, but Bob's firewall doesn't know that. It now thinks that anything which comes from 126.96.36.199 port 1414 and is addressed to Bob's IP address 188.8.131.52 and port 2828 is legitimate - it must be the response to the query which has just been sent.
There are some cases, such as hostile NATs & firewalls in which your encrypted packets do indeed get relayed through our root servers. Relaying through our root adds latency. The packets must travel farther physically than they would for a direct, peer to peer connection.
Coinciding with Halloween over the weekend, security researcher Samy Kamkar published details of a spooky firewall-busting technique he calls NAT Slipstreaming. It allows a remote attacker to punch through gateway and browser defenses to access services running on computers within a network, depending on the victim's configuration.
hi thanks for your help to get knowledge about UDP hole punching. i am somedoubt in NAT traversal .Is NAT Traversal can be configured manually in firewall to open the portlike port forwarding or it is working with some application program to openthe port permanently for UDP hole punching
Just drop your app into ProgramFiles, or you can even create an InnoSetup Installer if user installation is required. Run your app as a Windows Service, so that it will relaunch if there are any issues. You will need to punch a hole in your firewall for your app as well.
Then came the day that Microsoft released the Netflix Watch Instantly module for Windows 7's Windows Media Center. As a longtime Netflix subscriber (and, yes, I pay for my subscription), I wanted to see how well the feature worked in Windows 7's Media Center. I had used it before in Vista's Windows Media Center, but it had been a while. I launched Windows 7's Media Center and was happy to see the Netflix Watch Instantly module, which had not been there previously (I have Windows 7 set to automatically download and install updates). I went to launch Netflix Watch Instantly in Media Center, but instead of being asking for my login credentials, a window popped up saying that it couldn't connect. I could use Internet Explorer 8 in Windows 7 to watch the Netflix Watch Instantly service, so the problem was definitely isolated to Media Center. I rebooted into the Vista partition, and discovered the same problem there as well. It didn't take me long to make an educated guess that this was due to a firewall issue... I quickly confirmed my suspicions by temporarily disabling the firewall and then successfully connecting to Netflix in Media Center. The challenge I now had was to figure out what sort of exception I needed to create that would allow Netflix to connect in Media Center, but wouldn't punch too large a hole in the firewall. 2b1af7f3a8