Develop Reference

How do I get the actual ip address of the visitor instead of his public ip address?

I am using this code to get the actual ip address of the visitor my website but it returns the PUBLIC ip address which is same for everybody in our office but instead I want the actual ipv4 address of the visitor's system.
protected string GetIPAddress()
{
System.Web.HttpContext context = System.Web.HttpContext.Current;
string ipAddress = context.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
if (!string.IsNullOrEmpty(ipAddress))
{
string[] addresses = ipAddress.Split(',');
if (addresses.Length != 0)
{
return addresses[0];
}
}
return context.Request.ServerVariables["REMOTE_ADDR"];
}
protected string GetIPAddressLocal()
{
System.Web.HttpContext context = System.Web.HttpContext.Current;
string ipAddress = context.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
if (!string.IsNullOrEmpty(ipAddress))
{
string[] addresses = ipAddress.Split(',');
if (addresses.Length != 0)
{
return addresses[addresses.Length-1];
}
}
return context.Request.ServerVariables["REMOTE_ADDR"];
}
public static IPAddress GetIPAddress3(string hostName)
{
Ping ping = new Ping();
var replay = ping.Send(hostName);
if (replay.Status == IPStatus.Success)
{
return replay.Address;
}
return null;
}
private string GetIP()
{
string strHostName = "";
strHostName = System.Net.Dns.GetHostName();
IPHostEntry ipEntry = System.Net.Dns.GetHostEntry(strHostName);
string ipaddress = "";
return ipaddress.ToString();
}
public static string GetUserIP()
{
var ip = (System.Web.HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] != null
&& System.Web.HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"] != "")
? System.Web.HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"]
: System.Web.HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"];
if (ip.Contains(","))
ip = ip.Split(',').First().Trim();
return ip;
}
string ipaddress = GetIPAddress();
ViewBag.ip = ipaddress;
ViewBag.ip2= System.Net.Dns.GetHostEntry(System.Net.Dns.GetHostName()).AddressList.GetValue(1).ToString();
ViewBag.ip3 = Request.ServerVariables["REMOTE_ADDR"];
ViewBag.ip4 = System.Web.HttpContext.Current.Request.UserHostAddress;
ViewBag.ip5 = GetIPAddress3(System.Net.Dns.GetHostName());
ViewBag.ip6 = GetIP();
ViewBag.ip7 = GetUserIP();
I have used multiple function it returns either the servers ip address or the public ip address which is same for all the users. It doesnt return the actual ip address that the user system has.

I did it.
this is the solution:
$(document).ready(function () {
// NOTE: window.RTCPeerConnection is "not a constructor" in FF22/23
var RTCPeerConnection = /*window.RTCPeerConnection ||*/ window.webkitRTCPeerConnection || window.mozRTCPeerConnection;
if (RTCPeerConnection) (function () {
var rtc = new RTCPeerConnection({ iceServers: [] });
console.log(rtc);
if (1 || window.mozRTCPeerConnection) { // FF [and now Chrome!] needs a channel/stream to proceed
rtc.createDataChannel('', { reliable: false });
};
rtc.onicecandidate = function (evt) {
// convert the candidate to SDP so we can run it through our general parser
// see https://twitter.com/lancestout/status/525796175425720320 for details
if (evt.candidate) grepSDP("a=" + evt.candidate.candidate);
};
rtc.createOffer(function (offerDesc) {
grepSDP(offerDesc.sdp);
rtc.setLocalDescription(offerDesc);
}, function (e) { console.warn("offer failed", e); });
var addrs = Object.create(null);
addrs["0.0.0.0"] = false;
function updateDisplay(newAddr) {
if (newAddr in addrs) return;
else addrs[newAddr] = true;
var displayAddrs = Object.keys(addrs).filter(function (k) { return addrs[k]; });
if (displayAddrs[0] === null || displayAddrs[0] === '') {
$('#txtIpAddress').val(displayAddrs.join(" or perhaps "));
} else {
$('#txtIpAddress').val(displayAddrs[0]);
}
//$('#txtIpAddress').val(displayAddrs.join(" or perhaps "));
// console.log(displayAddrs[0]);
// alert(displayAddrs.join(" or perhaps "));
// document.getElementById('list').textContent = displayAddrs.join(" or perhaps ") || "n/a";
}
function grepSDP(sdp) {
var hosts = [];
sdp.split('\r\n').forEach(function (line) { // c.f. http://tools.ietf.org/html/rfc4566#page-39
if (~line.indexOf("a=candidate")) { // http://tools.ietf.org/html/rfc4566#section-5.13
var parts = line.split(' '), // http://tools.ietf.org/html/rfc5245#section-15.1
addr = parts[4],
type = parts[7];
if (type === 'host') updateDisplay(addr);
} else if (~line.indexOf("c=")) { // http://tools.ietf.org/html/rfc4566#section-5.7
var parts = line.split(' '),
addr = parts[2];
updateDisplay(addr);
}
});
}
})();
});

Discover all devices on LAN

In my Xamarin Forms application, I am trying to discover all devices on the local network that I am connected to. My approach is to first get the device IP address, and use to first 3 numbers to know what the gateway is (first number is always 192). And then, ping every address on that gateway. Here is my code:
public partial class MainPage : ContentPage
{
private List<Device> discoveredDevices = new List<Device>();
public MainPage()
{
InitializeComponent();
Ping_all();
}
private string GetCurrentIp()
{
IPAddress[] addresses = Dns.GetHostAddresses(Dns.GetHostName());
string ipAddress = string.Empty;
if (addresses != null && addresses[0] != null)
{
ipAddress = addresses[0].ToString();
}
else
{
ipAddress = null;
}
return ipAddress;
}
public void Ping_all()
{
string ip = GetCurrentIp();
if (ip != null)
{
//Extracting and pinging all other ip's.
string[] array = ip.Split('.');
string gateway = array[0] + "." + array[1] + "." + array[2];
for (int i = 2; i <= 255; i++)
{
string ping_var = $"{gateway}.{i}";
//time in milliseconds
Ping(ping_var, 4, 4000);
}
}
}
public void Ping(string host, int attempts, int timeout)
{
for (int i = 0; i < attempts; i++)
{
new Thread(delegate ()
{
try
{
System.Net.NetworkInformation.Ping ping = new System.Net.NetworkInformation.Ping();
ping.PingCompleted += new PingCompletedEventHandler(PingCompleted);
ping.SendAsync(host, timeout, host);
// PingCompleted never gets called
}
catch(Exception e)
{
// Do nothing and let it try again until the attempts are exausted.
// Exceptions are thrown for normal ping failurs like address lookup
// failed. For this reason we are supressing errors.
}
}).Start();
}
}
private void PingCompleted(object sender, PingCompletedEventArgs e)
{
string ip = (string)e.UserState;
if (e.Reply != null && e.Reply.Status == IPStatus.Success)
{
string hostname = GetHostName(ip);
string macaddres = GetMacAddress(ip);
var device = new Device()
{
Hostname = hostname,
IpAddress = ip,
MacAddress = macaddres
};
discoveredDevices.Add(device);
}
}
public string GetHostName(string ipAddress)
{
try
{
IPHostEntry entry = Dns.GetHostEntry(ipAddress);
if (entry != null)
{
return entry.HostName;
}
}
catch (SocketException)
{
}
return null;
}
public string GetMacAddress(string ipAddress)
{
string macAddress = string.Empty;
System.Diagnostics.Process Process = new System.Diagnostics.Process();
Process.StartInfo.FileName = "arp";
Process.StartInfo.Arguments = "-a " + ipAddress;
Process.StartInfo.UseShellExecute = false;
Process.StartInfo.RedirectStandardOutput = true;
Process.StartInfo.CreateNoWindow = true;
Process.Start();
string strOutput = Process.StandardOutput.ReadToEnd();
string[] substrings = strOutput.Split('-');
if (substrings.Length >= 8)
{
macAddress = substrings[3].Substring(Math.Max(0, substrings[3].Length - 2))
+ "-" + substrings[4] + "-" + substrings[5] + "-" + substrings[6]
+ "-" + substrings[7] + "-"
+ substrings[8].Substring(0, 2);
return macAddress;
}
else
{
return "OWN Machine";
}
}
}
I get to the part where I try to ping:
System.Net.NetworkInformation.Ping ping = new System.Net.NetworkInformation.Ping();
ping.PingCompleted += new PingCompletedEventHandler(PingCompleted);
ping.SendAsync(host, timeout, host);
But PingCompleted never gets called. No exception is thrown either. Any idea why? I'm running this on a physical Android device.
EDIT
PingCompleted started getting called for me now, not sure why it wasn't working before. But it now crashes in my GetMacAddress function on the line Process.Start(); because it can not find the resource.

I ended up using this really robust and easy to use library:
https://github.com/Yortw/RSSDP
It doesn't actually find all devices on the network, instead it uses SSDP (Simple Search Discovery Protocol) to quickly find all devices that are broadcasting a service with this protocol on the network. I filtered it to only scan devices running my app, which is what I actually needed. It takes only a second to discover my devices, which is much faster than pinging 255 addresses.
In the documentation you will see:
var deviceDefinition = new SsdpRootDevice()
{
CacheLifetime = TimeSpan.FromMinutes(30), //How long SSDP clients can cache this info.
Location = new Uri("http://mydevice/descriptiondocument.xml"), // Must point to the URL that serves your devices UPnP description document.
DeviceTypeNamespace = "my-namespace",
DeviceType = "MyCustomDevice",
FriendlyName = "Custom Device 1",
Manufacturer = "Me",
ModelName = "MyCustomDevice",
Uuid = GetPersistentUuid() // This must be a globally unique value that survives reboots etc. Get from storage or embedded hardware etc.
};
For the Location I set it as my device's IP. So that another device that discovers it can have the IP too. I don't think it's meant to be used this way, but it worked for me and I don't see why not.
I tested it on 2 physical Android devices.

Parsing out URLs in email messages

I'm having an issue in some of my code, i cannot seem to think of the best way to do this, all i want to do is extract a URL from a pop3 email message depending on if the domain is in the "to check" array, for example if "stackoverflow.com" is in the email message, i would extract all urls in the message body that contains "stackoverflow.com" in it, and just perform a quick WebClient() request with that url.
Code:
private void BgwEmails_DoWork_1(object sender, DoWorkEventArgs e)
{
try
{
bool finished = false;
Pop3Client pop3 = new Pop3Client();
if (pop3.Connected)
{
pop3.Disconnect();
}
pop3.Connect(txtBoxMailServer.Text, int.Parse(txtBoxPort.Text), chkSSL.Checked);
pop3.Authenticate(txtBoxUsername.Text, txtBoxPassword.Text, AuthenticationMethod.UsernameAndPassword);
int messageCount = pop3.GetMessageCount();
if (messageCount == 0)
{
return;
}
Helpers.ReturnMessage("[ " + messageCount + " ] Message(s) in your inbox.");
int count = 0;
for (int d = 1; d <= messageCount; d++)
{
bgwEmails.WorkerSupportsCancellation = true;
if (bgwEmails.CancellationPending)
{
e.Cancel = true;
Helpers.ReturnMessage($"Cancelling link activator ...");
return;
}
if (finished)
{
return;
}
OpenPop.Mime.Message message = null;
message = pop3.GetMessage(d);
if (null == message || null == message.MessagePart || null == message.MessagePart.MessageParts) {
continue;
}
string textFromMessage = null;
try
{
textFromMessage = message?.MessagePart?.MessageParts[0]?.GetBodyAsText();
} catch (Exception) {
continue;
}
MessagePart messagePart = message.MessagePart.MessageParts[0];
if (null == messagePart || null == messagePart.BodyEncoding || null == messagePart.Body || null == messagePart.BodyEncoding.GetString(messagePart.Body)) {
continue;
}
string linkToCheck;
using (var wc = new WebClient())
{
linkToCheck = wc.DownloadString("https://www.thesite.com/api.php?getActivationLinks=1");
}
var linksToClickArray = linkToCheck.Split(new[] { '\n' }, StringSplitOptions.RemoveEmptyEntries);
//Helpers.ReturnMessage(textFromMessage);
for (var i = 0; i < linksToClickArray.Length; i++)
{
var regex = new Regex(linksToClickArray[i], RegexOptions.IgnoreCase | RegexOptions.Multiline | RegexOptions.Singleline);
var matches = regex.Matches(textFromMessage);
foreach (Match match in matches)
{
if (match.Success)
{
count++;
Invoke(new MethodInvoker(() => { listBoxEmailsClicked.Items.Add("Clicked: " + match.Value); }));
using (WebClient wc = new WebClient())
{
Helpers.ReturnMessage(match.Value);
wc.DownloadString(match.Value);
}
}
}
}
if (null != textFromMessage)
{
Invoke(new MethodInvoker(() => { txtStatusMessages.AppendText(textFromMessage); }));
}
}
Helpers.ReturnMessage($"Emails downloaded successfully! You clicked [ " + count + " ] activation links.");
} catch (Exception ex) {
Helpers.ReturnMessage($"POP3 Error: " + ex.Message + ".");
}
}
I do a request here: https://www.thesite.com/api.php?getActivationLinks=1 which contains a list of domains to check for in the messages, they just come back one line at a time like:
thesite1.com
thesite2.com
etc
The code works as far as connetcing and downloading, i just cannot seem to think of a way to parse of the urls only if it matches a domain in the target list, any help or advice would be appreciated.

C# Socket: Client Mishandle 'a' as the Client's id

There are two programs that I made that didn't work. There are the server and the client. The server accepts many client by giving a user an ID (starting from 0). The server sends out the command to the specific client based up the server's id. (Example: 200 client are connected to 1 server. The server's selected id is '5', so the server will send the command to all of the client, and the client will ask the server what ID he wants to execute his command on, and if it's '5', that client will execute and send data to the server). The client has many commands, but to create the smallest code with the same error, I only use 1 command (dir). Basically, the server sends the command to the client and if it matches with the client current id and the server current id, it will process the command. By default, the server's current ID is 10. Here are the list of the commands to help the people who wants to answer:
Server Command:
list (Shows all of the users ID connected and the server's current ID) --> Happens on server
dir (request the client to send its dir listing) --> Sent by the client, read by the Server
set (set the server's current id to any number) (example: 'set 4')
Client:
using System;
using System.Speech.Synthesis;
using System.Windows.Forms;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using System.Net.Sockets;
using System.Net;
namespace clientControl
{
class Program
{
public static string directory = #"C:\";
public static int id = -10;
public static Socket sck = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
static void Main(string[] args)
{
Connect();
getSession();
ReadResponse(sck);
}
static byte[] readResponseFunc()
{
long fileSize = 0;
string fileSizeInString = null;
byte[] fileSizeInByteArray = new byte[1024];
int fileSizeLength = sck.Receive(fileSizeInByteArray);
for (int i = 0; i < fileSizeLength; i++)
{
fileSizeInString = fileSizeInString + (char)fileSizeInByteArray[i];
}
try
{
fileSize = Convert.ToInt64(fileSizeInString);
}
catch { Console.WriteLine(fileSizeInString); }
sck.Send(Encoding.ASCII.GetBytes("a"));
byte[] responseUnknown = new byte[1];
sck.Receive(responseUnknown);
if (Encoding.ASCII.GetString(responseUnknown) == "b")
{
byte[] dataInByteArray = new byte[fileSize];
int dataLength = sck.Receive(dataInByteArray);
return dataInByteArray;
}
return Encoding.ASCII.GetBytes("ERROR RESPONSE FUNC");
}
static void getSession()
{
byte[] message_1 = Encoding.ASCII.GetBytes("make_id");
sck.Send(Encoding.ASCII.GetBytes(message_1.Length.ToString()));
byte[] responseUnknown = new byte[1];
if (Encoding.ASCII.GetString(responseUnknown) == "a")
{
sck.Send(Encoding.ASCII.GetBytes("b"));
sck.Send(message_1);
}
byte[] receivedID = readResponseFunc();
id = Convert.ToInt32(Encoding.ASCII.GetString(receivedID));
}
static bool SocketConnected(Socket s)
{
bool part1 = s.Poll(1000, SelectMode.SelectRead);
bool part2 = (s.Available == 0);
if (part1 && part2)
return false;
else
return true;
}
static void ReadResponse(Socket sck)
{
while (true)
{
if (SocketConnected(sck) == true)
{
try
{
string response = Encoding.ASCII.GetString(readResponseFunc());
byte[] message_1 = Encoding.ASCII.GetBytes("get_id");
sck.Send(Encoding.ASCII.GetBytes(message_1.Length.ToString()));
byte[] responseUnknown = new byte[1];
if (Encoding.ASCII.GetString(responseUnknown) == "a")
{
sck.Send(Encoding.ASCII.GetBytes("b"));
sck.Send(message_1);
}
byte[] response_2InByteArray = readResponseFunc();
string response_2 = Encoding.ASCII.GetString(response_2InByteArray);
if (Convert.ToInt32(response_2) == id)
{
if (response == "dir")
{
string resultOfDirring = "Current Directory: " + directory + "\n\n";
string[] folderListingArray = Directory.GetDirectories(directory);
foreach (string dir in folderListingArray)
{
string formed = "DIRECTORY: " + Path.GetFileName(dir);
resultOfDirring = resultOfDirring + formed + Environment.NewLine;
}
string[] fileListingArray = Directory.GetFiles(directory);
foreach (var file in fileListingArray)
{
FileInfo fileInfo = new FileInfo(file);
string formed = "FILE: " + Path.GetFileName(file) + " - FILE SIZE: " + fileInfo.Length + " BYTES";
resultOfDirring = resultOfDirring + formed + Environment.NewLine;
}
byte[] message_11 = Encoding.ASCII.GetBytes(resultOfDirring);
sck.Send(Encoding.ASCII.GetBytes(message_11.Length.ToString()));
byte[] responseUnknown_11 = new byte[1];
if (Encoding.ASCII.GetString(responseUnknown_11) == "a")
{
sck.Send(Encoding.ASCII.GetBytes("b"));
sck.Send(message_11);
}
}
}
else { }
}
catch { if (SocketConnected(sck) == false) { Console.WriteLine("Client Disconnected: " + sck.RemoteEndPoint); break; }; }
}
else if (SocketConnected(sck) == false) { Console.WriteLine("Client Disconnected: " + sck.RemoteEndPoint); break; }
}
}
static void Connect()
{
while (true)
{
try
{
sck.Connect(IPAddress.Parse("127.0.0.1"), 80);
break;
}
catch { }
}
}
}
}
Server:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.IO;
using System.Text;
using System.Threading;
namespace serverControl
{
class Program
{
public static int ftpNum = 1;
public static List<int> listOfClient = new List<int>();
public static TcpListener server = new TcpListener(IPAddress.Parse("127.0.0.1"), 80);
public static string message = null;
public static int id = 0;
public static int selected_id = 10;
static void Main(string[] args)
{
server.Start();
Thread startHandlingClientThread = new Thread(startHandlingClient);
startHandlingClientThread.Start();
while (true)
{
Console.Write(":> ");
string rawmessage = Console.ReadLine();
if (rawmessage == "list")
{
Console.WriteLine("SELECTED ID: " + selected_id);
Console.WriteLine("List of Clients ID:");
for (int i = 0; i < listOfClient.Count; i++)
{
Console.WriteLine(listOfClient[i]);
}
message = rawmessage+"PREVENT_REPETITION_IN_COMMAND";
}
else if (rawmessage.Contains("set ")) { int wantedChangeId = Convert.ToInt32(rawmessage.Replace("set ", "")); selected_id = wantedChangeId; message = rawmessage+ "PREVENT_REPETITION_IN_COMMAND"; }
else
{
message = rawmessage;
}
}
}
static byte[] readResponseFunc(Socket sck)
{
long fileSize = 0;
string fileSizeInString = null;
byte[] fileSizeInByteArray = new byte[1024];
int fileSizeLength = sck.Receive(fileSizeInByteArray);
for (int i = 0; i < fileSizeLength; i++)
{
fileSizeInString = fileSizeInString + (char)fileSizeInByteArray[i];
}
fileSize = Convert.ToInt64(fileSizeInString);
sck.Send(Encoding.ASCII.GetBytes("a"));
byte[] responseUnknown = new byte[1];
sck.Receive(responseUnknown);
if (Encoding.ASCII.GetString(responseUnknown) == "b")
{
byte[] dataInByteArray = new byte[fileSize];
int dataLength = sck.Receive(dataInByteArray);
return dataInByteArray;
}
return Encoding.ASCII.GetBytes("ERROR RESPONSE FUNC");
}
static void startHandlingClient()
{
while (true)
{
handleClient(server);
}
}
static void handleClient(TcpListener clientToAccept)
{
Socket sck = clientToAccept.AcceptSocket();
Thread myNewThread = new Thread(() => ReadResponse(sck));
myNewThread.Start();
}
static bool SocketConnected(Socket s)
{
bool part1 = s.Poll(1000, SelectMode.SelectRead);
bool part2 = (s.Available == 0);
if (part1 && part2)
return false;
else
return true;
}
static void ReadResponse(Socket sck)
{
Thread myNewThread = new Thread(() => SendtoClient(sck));
myNewThread.Start();
Thread.Sleep(2000);
while (true)
{
if (SocketConnected(sck) == true)
{
try
{
byte[] dataInByteArray = readResponseFunc(sck);
string response = Encoding.ASCII.GetString(dataInByteArray);
Console.WriteLine("res: " + response);
if (response != "make_id" && response != "get_id") { Console.WriteLine(response); }
if (response == "make_id")
{
Console.WriteLine("Someone wants an ID");
byte[] message_1 = Encoding.ASCII.GetBytes(id.ToString());
listOfClient.Add(id);
// START
sck.Send(Encoding.ASCII.GetBytes(message_1.Length.ToString()));
byte[] responseUnknown = new byte[1];
if (Encoding.ASCII.GetString(responseUnknown) == "a")
{
sck.Send(Encoding.ASCII.GetBytes("b"));
sck.Send(message_1);
}
id++;
}
if (response == "get_id")
{
byte[] message_1 = Encoding.ASCII.GetBytes(selected_id.ToString());
sck.Send(Encoding.ASCII.GetBytes(message_1.Length.ToString()));
byte[] responseUnknown = new byte[1];
if (Encoding.ASCII.GetString(responseUnknown) == "a")
{
sck.Send(Encoding.ASCII.GetBytes("b"));
sck.Send(message_1);
}
}
}
catch { if (SocketConnected(sck) == false) { Console.WriteLine("Client Disconnected: " + sck.RemoteEndPoint); break; }; }
}
else if (SocketConnected(sck) == false) { Console.WriteLine("Client Disconnected: " + sck.RemoteEndPoint); break; }
}
}
static void SendtoClient(Socket sck)
{
string tempmessage = null;
while (true)
{
if (SocketConnected(sck) == true)
{
if (tempmessage != message)
{
if (!message.Contains("PREVENT_REPETITION_IN_COMMAND"))
{
byte[] message_1 = Encoding.ASCII.GetBytes(message);
sck.Send(Encoding.ASCII.GetBytes(message_1.Length.ToString()));
byte[] responseUnknown = new byte[1];
if (Encoding.ASCII.GetString(responseUnknown) == "a")
{
sck.Send(Encoding.ASCII.GetBytes("b"));
sck.Send(message_1);
}
}
tempmessage = message;
}
}
else if (SocketConnected(sck) == false)
{ Console.WriteLine("Client Disconnected: " + sck.RemoteEndPoint); break; }
}
}
}
}
Problem:
The problem is within the GetSession or the ReadResponseFunc function. The client thinks that his ID received by the server is 'a' (it's suppose to be an integer). I don't want a solution that suggest me to use other libs or
the TcpClient class
Bounty:
I'll put up a bounty with no expiry time to those who solve the problem.

The logic in your code is very confusing. My question to you: Why are you sending 'a' and 'b' back and forth between the server and client? Is it some sort of confirmation that the message has been received?
Anyways, throughout the quick tests I've done just now, it seems that the problem is Line 59 of your server:
sck.Send(Encoding.ASCII.GetBytes("a"));
Here's what I figured out during testing:
Server executes.
Client executes.
Client sends server the length of "make_id" (Line 51 of client)
Client waits for a response to return.
Server reads the value and sends back 'a' (Line 59 of server)
You may want to spend some time to straighten out your protocol so it's less confusing and more organized. That would help people like me and you spot bugs much more easily.

The user 'Bobby' has already found your problem. Credits go to him.
I further suggest that you use less threads, as thread synchronisation needs some effort when doing it right: all data that is accessed from different threads must be secured by locks, so that no outdated values remain in the CPU caches. Use .net Monitor from the "threading synchronisation primitives" for that job.
About the threads themselves:
You should have only one thread in the server. This thread takes all clients from a list (secured by Monitor), in which they were added when connection attempts were received. On each client it checks for incoming messages, evaluates them and replies with own messages if needed.
The client also has just one thread, that will loop (dont forget a sleep in the loop or you will have 100% usage of the used CPU core), send messages when desired and wait for replies when messages were sent.
About the messages:
I already gave some proposals in a comment to Bobby's answer. I suggest you create a CMessage class that has a Serialize() and Deserialze() to create a byte array to send from the CMessage members (serializing the content) or vice versa filling the members from the received bytes. You then may use this class in both programs and you'll have common solution.

C# Testing Multiple Proxies

I've been scratching my head about this. I'm wondering how I can test multiple proxies at once, I know how to test one at a time but that takes alot of time.
I'm using this code to test a proxy
public bool testProxy( string proxy, int port )
{
try
{
WebClient web = new WebClient();
web.Proxy = new WebProxy( proxy, port);
web.DownloadString("http://www.google.com/ncr");
return true;
}
catch
{
return false;
}
}
Now how would I test them with multithreading or whatever I need to use?
Because at the moment I'm doing this when a button is pressed, which is time consuming
if (proxy_list.Count > 0)
{
for (int i = 0; i < proxy_list.Count; i++)
{
string Proxy = proxy_list[i];
string[] vars = Proxy.Split( ':' );
if (vars.Length == 2)
{
proxy = vars[0];
port = int.Parse(vars[1]);
if ( !testProxy( proxy, port ) )
{
proxy_list.RemoveAt(i);
}
}
else
{
proxy_list.RemoveAt(i);
}
textBox3.Text = proxy_list.Count.ToString();
this.Refresh();
}
}
Test proxy function
public void testProxy(string proxy, int port, int listpos)
{
try
{
WebClient web = new WebClient();
web.Proxy = new WebProxy(proxy, port);
web.DownloadString("http://www.google.com/ncr");
}
catch
{
proxy_list.RemoveAt(listpos);
}
}

You can try this (multithread)
if (proxy_list.Count > 0)
{
for (int i = 0; i < proxy_list.Count; i++)
{
string Proxy = proxy_list[i];
string[] vars = Proxy.Split( ':' );
if (vars.Length == 2)
{
proxy = vars[0];
port = int.Parse(vars[1]);
Thread TestProxy = new Thread(testProxy( proxy, port, i));
TestProxy.Start();
}
else
{
proxy_list.RemoveAt(i);
}
textBox3.Text = proxy_list.Count.ToString();
this.Refresh();
}
}
public bool testProxy( string proxy, int port, int listpos )
{
try
{
WebClient web = new WebClient();
web.Proxy = new WebProxy( proxy, port);
web.DownloadString("http://www.google.com/ncr");
return true;
}
catch
{
proxy_list.RemoveAt(listpos);
}
}