I'm creating a pub sub style communication using zeromq c# implementation. It all works fine on my local machine but when running the client component (publisher) against a remote address I get an "Address not available". So far as I understand it the Publisher will Bind to an endpoint and the Subscriber will Connect.
Am I misunderstanding something or should publisherSocket.Bind("tcp://someRemoteIP:5001") work?
You bind to a local endpoint, and connect to a remote endpoint.
The local endpoint consists of a protocol ("tcp://"), an interface ("*", "localhost", "eth0" (or such) or the IP address of an interface), and a port number (":5001").
The remote endpoint consists of a protocol ("tcp://"), an IP address or domain name ("someremoteIP") and the port number.
Hope that helps.
Related
I have a very simple http server:
TcpListener server = new TcpListener(System.Net.IPAddress.Any, 80);
server.Start();
var client = server.AcceptTcpClient();
var ip = client.Client.RemoteEndPoint;
// ip address in here is: 166.72.162.85
// etc. read request and write response....
I am making that request with my phone that is connected to AT&T 3G network. And my server detects the ip address 166.72.162.85
Now here is my question. I am asking this question primary to learn. Why is it that google captures a different IP address? How can I capture 2600:387:9:3::c7 with my TcpListener?
It looks like you're on a dual stacked network - you have both IPv4 and IPv6 connectivity, which a bit like being connected to two separate "Internets" at the same time.
Your server is probably accessible from only one of these "Internets" - the IPv4 Internet. Google is accessible from both. We can easily check that by resolving www.google.com to an IP address. Here's the result on my machine:
Note the first result - 2a00:1450:4001:821::2004. It's an IPv6 address, and that's the first address your operating system will try to connect to when accessing www.google.com because modern operating systems prefer IPv6 over IPv4. So your connection to Google goes over IPv6, which will see you coming from your IPv6 address (2600:387:9:3::c7).
When connecting to your IPv4-only sever, the connection is made over IPv4 - from your IPv4 address, which is 166.72.162.85 to the server's IPv4 address.
To reach your server using IPv6, you'd need to make it accessible via IPv6:
The machine on which you run your server must have a public IPv6 address
The client has to access the machine either directly by its IPv6 address, or a domain name which has a AAAA record, which is a DNS record for IPv6 addresses
On top of that, you need to make sure that your server software binds to the IPv6 address of the machine. Your code binds to System.Net.IPAddress.Any, which is equivalent to 0.0.0.0, meaning "any IPv4 address". Instead, you'd need to bind to IPAddress.IPv6Any, which is equivalent to 0:0:0:0:0:0:0:0 (or ::), meaning "any IPv6 address".
BTW, you can try getting your IP from the IPv4-only Google at https://ipv4.google.com/. It should return the same 166.72.162.85 that you're seeing in your server.
Google is showing an IPv6 address, your code is showing IPv4.
Note you can also see different IP on the receiving end depending on the route the traffic has taken to get there, like if there were a proxy involved you would see the IP of the proxy and not the actual IP of the source.
I have Windows Server in VirtualBox and NATed port 80 for that.
Request.UserHostAddress returns local IP of virtual network.
How should i get IP of user?
The problem you've got is that you can't see beyond NATing. NAT stands for Network Address Translation so in this instance, you're seeing the public IP address of the NAT device, not the client. That's just the way it works. It's possible for the client to send its local IP address but you'd need to have something on the client to do that.
A different option is to switch from NAT to Bridged networking. Bridged means that the virtual network the VM is on is joined side-by-side with the physical network the host is on. This means they'll have IP addresses which are on the same subnet and are routable from anything else on the same network. Bridges act like switches/hubs, NATs act like routers.
As long as your server / client don't have any NAT devices between them, the IPs should be readily visible using the standard mechanisms (eg context.Request.ServerVariables["REMOTE_ADDR"], Request.UserHostAddress, etc)
Do you want to get the user's public IP address?
Easiest approach is to simply create a PHP script to echo the remote address, or use an existing API that does so.
PHP:
<?php
echo $_SERVER["REMOTE_ADDR"];
?>
C#:
using (var client = new HttpClient()) {
var response = await client.GetStringAsync(new Uri("URL"));
IPAddress ip;
if (IPAddress.TryParse(response, out ip)) {
//Success
}
}
Writing a chat program (as so many do) and i have found that i would like to be able to get the clients to connect to the server automatically.
However, the IP address of the server would not be permanent, so i cannot just hard-core it into the program
In TCP, I'm looking for some sort of broadcast feature, that allows the client to know where the server is
Any ideas?
EDIT: should have said, this will be a LAN program only - no outside connections
If you are talking about a chat in a LAN and you can't or don't want to use DNS for some reason, you could implement, or find an implementation of, the discovery protocol used by UPnP. The SSDP is based on a UDP broadcast. It is, afaik, not possible to multicast via TCP, because TCP needs a session.
If you want to use the chat server over the internet you have no choice but to use DNS. Look for a dynamic dns provider (I use selfhost.bz). In C# you can then resolve the hostname to an IP address as described in the other answers. If you have a hostname to connect to it will probably be enough to pass that to the socket, though:
socket.Connect("myhostname.selfhost.bz", ...
Edit: Since you say you're in a LAN, a few more details on SSDP. The protocol does way more, than you actually need. If you're thinking of implementing it yourself, don't stick to it exactly. Just make your clients send a broadcast on a specified port. The server permanently listens on that port, answering with a predefined message, once it receives a message. When the client receives that answer, it will know that the sender is a valid server.
Use DNS. Resolve the hostname in your app and connect to the IP it resolves to. You'll need dynamic DNS since you say the IP isn't permanent.
Use the below process to find server IP address
public string GetIPAddress()
{
string strHostName = System.Net.Dns.GetHostName();
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
return ipAddress.ToString();
}
You can also use
Request.ServerVariables["LOCAL_ADDR"];
I had an idea: just get the server to write the IP address/port/whatever to a textfile somewhere on the (public) network, and the clients can read the text file
Obviously, if the text file is not there or empty, no server is running...
Is this such a bad idea?
I'm using the following code to get DHCP server address from one of my network interfaces:
System.Net.NetworkInformation.NetworkInterface networkInterface;
// ... get one of the network interfaces
var properties = networkInterface.GetIPProperties();
var addresses = properties.DhcpServerAddresses;
My network interface is set to a fixed address (not assigned by DHCP) and I'm getting one address from that code, it's 255.255.255.255. Anybody can tell me why? And how can I check if a network interface uses a DHCP or fixed address.
The address 255.255.255.255 is a broadcast address, which is used by the DHCP protocol to broadcast availability packets. When you're not using DHCP this is the address assigned as a DHCP server, because it will allow the network to automatically discover any DHCP servers (usually routers) on the network.
You can use this to check for DHCP:
bool isDhcp = networkInterface.GetIPProperties()
.GetIPv4Properties()
.IsDhcpEnabled;
It isn't a 'real' IP address as it can't be assigned to a host. It simply means "broadcast everywhere".
I think it's safe to assume that when you find 255.255.255.255 as DHCP server address, the adapter you're querying has a fixed IP address, or APIPA (which happens when an adapter is set as DHCP client, but no DHCP server has responded for a preset period of time).
But the IsDhcpEnabled property that #Polynomial mentions is safer to rely on.
I am using TcpClient to listen on a port for requests. When the requests come in from the client I want to know the client ip making the request.
I've tried:
Console.WriteLine(tcpClient.Client.RemoteEndPoint.ToString());
Console.WriteLine(tcpClient.Client.LocalEndPoint.ToString());
var networkStream = tcpClient.GetStream();
var pi = networkStream.GetType().GetProperty("Socket", BindingFlags.NonPublic | BindingFlags.Instance);
var socketIp = ((Socket)pi.GetValue(networkStream, null)).RemoteEndPoint.ToString();
Console.WriteLine(socketIp);
All of these addresses output 10.x.x.x addresses which are private addresses and are clearly not the address of the clients off my network making the requests. What can I do to get the public ip of the clients making the requests?
Edit:
We are using an Amazon EC2 Load Balancer with tcp forwarding. Is there a way to get the true client ip in this set up?
Does this work:
((IPEndPoint)tcpClient.Client.RemoteEndPoint).Address.ToString()
If the client is connecting to you via an internal network I am not sure you can get their public IP since the connection to get back to the client would not need that information.
It sounds like perhaps your server is behind a load balancer or router using NAT. In this case, the IP packet won't have the originating client's address, but the address of the NAT router. Only the NAT router knows the sender's address (on an IP level).
Depending on whatever higher-level protocol you might be using on top of TCP, you may be able to get client identification from that, although it's much easier to spoof such information at higher levels, if that may be a concern.
If you need this data only for research purposes, your NAT device may keep a log.
If it's a requirement that you get the true originating IP packet in real time, you may have to have to reconfigure your router or have your server moved to the DMZ, but that's a whole nother ball of wax. Talk to your network guys, as they would certainly know more about this than I (I'm not a network expert).
Simply use the connection socket object of Socket class which you have used to accept the client.
connectionSocket.RemoteEndPoint.toString();
AdresseIP = DirectCast(SocketClient.Client.RemoteEndPoint, IPEndPoint).Address.ToString