We have a asp.net 3.5 web application running on a hosting company's web server that's got a very strict firewall setup. The web application communicates with our sql server express 2005 which is on a completely different network.
The problem is that the web applications sends our sql server a random port number to connect to when it connects to our sql server on port 1433. Hence the web application can not connect to our sql server because then they have to open a whole range off port numbers on the firewall which they are not prepared to do.
My question is the following. Can you specify either in your connection string or somewhere in your web.config the port the client sends to sql server to connect back to on?
Thanks
If I'm getting you right, you want to do something that goes against how TCP/IP port handling is supposed to work.
You want the web application to always use the same port when connecting to your SQL server? This would mean you can only have one connection open at any given time, and so only one user at any given time. The client is supposed to communicate with a server from a "random" port. It's the basics of networking. At least how I learned it.
I'm not sure you can even force it to use the same port every time, and even if you can I'd advice against it.
I'd say the problem is the firewall, and not your application. I can understand that the SQL server only wants to speak to the IP address that your site is on, but it shouldn't really care which port the client wants to talk over (something like [website-ip]:* -> [sql-ip]:1433). To me, it seems like who ever set up the firewall has some kind of crazy firewall ideas, but maybe that's just me.
Is it possible that your SQL Server Express is configured to listen on dynamic ports? If the 'TCP Dynamic Ports' value is 0, I think it will be dynamic even if you have a specific port configured. That value should be cleared completely.
You can specify port if you are using TCP/IP.
For ex:
Data Source=190.190.200.100,1433;Network Library=DBMSSOCN;Initial Catalog=myDataBase;User ID=myUsername;Password=myPassword;
where DBMSSOCN=TCP/IP
Related
I need to write my first socket program involving TCP connections. In the program I have created there is a client and server, both of which are the machine I am coding on.However,it requires that I pass the port number as a command line argument. How do I accomplish this?
The answer is simple : Make sure your server and your client agree on the port to use. As long as the port is available and can be used, set up the connected so that the client and server use that same port.
Here's a link that explain the different ranges available for TCP and UDP ports.
As an exemple, the port 3074 is used by microsoft for its Xbox live service. Making an application using this port might interfere with the service.
The port used will be defined either in a configuration file or hard-coded in the source code of both the server and the client. You should easily be able to find it with a quick look at the code or the directory which contains the application.
I noticed with Postgres and other databases, the database itself runs a local version of a server.
For example, mine is running on localhost:5432.
Curiously, I went to my web browser and tried typing in that address to see what I'd get, but I got a response that "This Web Page is Not Available".
I also tried things like localhost:5432/mydata but also to no avail.
Shouldn't I be able to see something if I visit the database through my web browser? If yes, how do you do it? If not, why not?
Postgres is a service running on a port. A web server is also a service running on a port (80 and/or 443 usually). There are a lot of things running on various ports on any server, heck, on any single computer. That doesn't mean that everything is interchangeable. Ports 80 and 443 are commonly agreed to serve HTTP(S) connections. HTTP is a specific protocol which specifies how two things can communicate on a specific port. Postgres is not speaking HTTP; you need to speak Postgres' particular protocol if you want to talk to it. The browser does not speak that protocol, and Postgres doesn't by default offer communication in any protocol a browser understands.
A web browser expects to "talk" to servers using a protocol it supports. Webbrowsers support obviously http. Some do support other protocols, like ftp. But your postgres does not speak http. So you don't see anything. The port number is just telling over which channel the server is accessible. Any protocol can be routed over any port, but usually http can be reached over port 80. Your postgress over port 5432.
I want to develop an iPhone app with a simple IM feature. I am thinking about setting up an HTTP server on an iPhone. If the iPhone is using wifi and is behind a firewall, how can I make sure that other iPhone clients can connect to it?
It's not the firewall that will disturb the connection as much it is the NAT.
When you are connected through wireless router to connect the internet you are surfing via NAT. it means you dont really have an extenral IP but once you initiate connection the router will map your intenral IP to one of his externatl ports and for certain time window he will pass connections to you if he will get it to the right port.
That being said, there is no actual way of setting a server behind a NAT unless you can configure port forwarding in the router and internal static IP.
Hope i was clear enough, good luck
I do not really think that you need to get an HTPP server up and running on iPhone to make an application that can send and receive messages (IM). The idea of making one iPhone user to directly connect to one another does not seem right to me since the users will need to know IP addresses of one another to do that.
Interconnectivity between different users of the chat can be solved by making your application communicate via a dedicated TCP port. It is generally advisable to choose ports with a number higher than 1024 since those below are generally found on the list of so-called well-known ports and are used for Web (like port 80), FTP (port 21), SSH (22), DNS (53), etc., it will be the responsibility of the user to make sure the port used by your application is open on the firewall. In order to solve this problem you can actually use port 80 for communication if you find that the port you have selected is blocked. You can do this because you know that this port will not be blocked in most cases. Indeed Yahoo Messenger is reported to use this technique when the firewall blocks the port it uses for communication.
The port should be used by your application to connect to the Web-server that will actually store user credentials, perform authentication, message transmission, etc., and the server should reside on capable hardware to be able to support large number of simultaneous connections. I can suggest using either a VPS (like the one provided by Linode) or a cloud (like Amazon EC2, Google Application Engine, Rackspace).
I have a simple node.js client and server programs running on one machine and when I try to connect to the server with second instance of client program simultaneously I get EADDRINUSE, Address already in use error. Is it possible to have two or more TCP based socket client connections (created with createConnection) to one server (created with createServer) on the same machine, or only one client program can be connected to the server at the same time?
Yes, it's possible. Infact, very common. Many applications open dozens, or hundreds of connections to the same server. It sounds like your client program is binding on a port. Only the server should be binding on a port. You should verify.
The client will usually use a random port between 1024-65535, as assigned by your OS. You don't need to worry about it. Since the client is initiating a connection to the server, the server port must unique to one program. Which is why your problem signifies you are trying to start the server twice. Please see http://www.tcpipguide.com/free/t_TCPIPClientEphemeralPortsandClientServerApplicatio.htm
I do know that I can't have two programs listening to the same port, but I am wondering if it is possible to fake it somehow, for an example:
My machine has two applications, one listening to port 80 and the other to port 6653.
If I get an incoming connection, let's say mysite.com:80/chat then it would be forwarded internally to the application listening on port 6653 and the data returned from that server would be forwarded back to port 80 somehow.
The reason I want to accomplish this is because there are many firewalls that seem to block connections to ports other than 80.
I have a chat server that I want to run on port 80, perhaps I could get another IP and machine for that, but it feels like too much trouble for a single chat server.
Any helpful feedback would be appreciated. Thanks!
You can probably do this with mod_rewrite if you're running Apache. That link has plenty of examples, including what you want (I think).
EDIT: I see you've updated the tags to say "asp.net". I'm guessing that you're not running Apache, then. I'm sure there is a similar tool for IIS, or you can use a proxy server that does the same thing.
There is a module called URL Rewrite that you can install on Windows Server 2008 (and R2) that is functionally the same as Mod_Rewrite. Download it here: http://www.iis.net/download/URLRewrite