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How to Ping for IPv4 only?

I know my router's IPv4 address. But when I Ping using TTL = 1 I don't get that IP. Rather, I get its IPv6 address. (I know of address.MapToIPv4() but that's only for IPv4s that were changed into IPv6s.)
So how do I ping for IPv4 only (like tracert's /4 switch)?
var reply = new Ping().Send("example.com", 10000, new byte[] { 1 }, new PingOptions(1, true));

Looking at the source code (Reference Source, GitHub), if the parameter passed to Send() is a name then Dns.GetHostAddresses() is used to resolve it and the first address returned is what's used. Thus, if that first address is an IPv6 address then that address is what will be pinged and there's no way to change that behavior.
Instead, you could call Dns.GetHostAddresses() yourself, filter the results to include or prefer IPv4 addresses, and pass that to Ping.Send():
IPAddress addressToPing = Dns.GetHostAddresses("example.com")
.First(address => address.AddressFamily == AddressFamily.InterNetwork);
using (Ping ping = new Ping())
{
PingReply reply = ping.Send(addressToPing, 10000, new byte[] { 1 }, new PingOptions(1, true));
// Do something with reply...
}

Retrieving Subnet Mask Address From .NET HttpRequest class

Giving an object instance from the class System.Web.HttpRequest, say myRequest, then using the property System.Web.HttpRequest.UserHostAddress I can retrieve the IP address of the remote client:
string myIp = myRequest.UserHostAddress;
(...)
My need is to retrieve the IP address of the subnet mask of the remote client exclusively from the instance myRequest.
I know that the following is not possible but I would like to accomplish something similar:
string myMaskIp = myRequest.UserHostMaskAddress;
(...)
This because I can't check the local device network interfaces as I could with System.Net.NetworkInformation namespace, so my only available object to probe is the http request made from the remote client to the server.
Thank you very much for your help

I'm pretty sure you can not determine a subnet mask by simply making a request to a remote host - even if the remote host is you.

Oldyis is right for the general case, however it is possible to determine a classful subnetmask from the IPv4 address. Without any further information, determining an classless subnetmask is indeed impossible.
Keep in mind that the classful adressing scheme is virtually not used any more.
Here is an example from this project:
/// <summary>
/// Returns the classfull subnet mask of a given IPv4 network
/// </summary>
/// <param name="ipa">The network to get the classfull subnetmask for</param>
/// <returns>The classfull subnet mask of a given IPv4 network</returns>
public static Subnetmask GetClassfullSubnetMask(IPAddress ipa)
{
if (ipa.AddressFamily != AddressFamily.InterNetwork)
{
throw new ArgumentException("Only IPv4 addresses are supported for classfull address calculations.");
}
IPv4AddressClass ipv4Class = GetClass(ipa);
Subnetmask sm = new Subnetmask();
if (ipv4Class == IPv4AddressClass.A)
{
sm.MaskBytes[0] = 255;
}
if (ipv4Class == IPv4AddressClass.B)
{
sm.MaskBytes[0] = 255;
sm.MaskBytes[1] = 255;
}
if (ipv4Class == IPv4AddressClass.C)
{
sm.MaskBytes[0] = 255;
sm.MaskBytes[1] = 255;
sm.MaskBytes[2] = 255;
}
return sm;
}
(Think of the SubnetMask class as a byte array of length four)

Resolve HostName to IP

I have been through a lot of googling for this, I found a lot of examples none of which was working for me. This is a simple issue which I feel has a simple answer without defining new classes\modules etc...
My code is this :
Console.WriteLine ("Please enter an IP address or hostname");
string host = Console.ReadLine ();
***IP = resolved "host"***
Socket s = new Socket (AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
s.Connect (IP, 80);
s.close();
How do I actually resolve the IP variable?

You can simply use the DNS class to do so:
IPHostEntry hostEntry;
hostEntry= Dns.GetHostEntry(host);
//you might get more than one ip for a hostname since
//DNS supports more than one record
if (hostEntry.AddressList.Length > 0)
{
var ip = hostEntry.AddressList[0];
Socket s = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
s.Connect(ip, 80);
}

string howtogeek = "www.howtogeek.com";
IPAddress[] addresslist = Dns.GetHostAddresses(howtogeek);
foreach (IPAddress theaddress in addresslist)
{
Console.WriteLine(theaddress.ToString());
}
from howtogeek

Please take the note that accepted answer can resolve to IPv6. I attempted to connect to service that does not accept IPv6 as input string.
Therefore try this snippet if you care to get IPv4:
using System.Linq;
string host = "google.com";
Dns.GetHostEntry(host).AddressList.First(addr => addr.AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork)

This is the method I use to resolve a hostname to IPv4 and / or IPv6.
using System.Net:
// A host can have multiple IP addresses!
public static IPAddress[] GetIPsByName(string hostName, bool ip4Wanted, bool ip6Wanted)
{
// Check if the hostname is already an IPAddress
IPAddress outIpAddress;
if (IPAddress.TryParse(hostName, out outIpAddress) == true)
return new IPAddress[] { outIpAddress };
//<----------
IPAddress[] addresslist = Dns.GetHostAddresses(hostName);
if (addresslist == null || addresslist.Length == 0)
return new IPAddress[0];
//<----------
if (ip4Wanted && ip6Wanted)
return addresslist;
//<----------
if (ip4Wanted)
return addresslist.Where(o => o.AddressFamily == AddressFamily.InterNetwork).ToArray();
//<----------
if (ip6Wanted)
return addresslist.Where(o => o.AddressFamily == AddressFamily.InterNetworkV6).ToArray();
//<----------
return new IPAddress[0];
}

If all you want is to resolve a string that could represent either a hostname OR an IP address, you probably want to use System.Net.Dns.GetHostAddresses() rather than System.Net.Dns.GetHostEntry().
GetHostAddresses() skips the DNS lookup if the string parses to an IP address already, while GetHostEntry() will do a reverse lookup for the hostname.
https://learn.microsoft.com/en-us/dotnet/api/system.net.dns.gethostaddresses

The IpAddress has the appropriate method for parsing hostname to IpAddress.
IPAddress addr = IPAddress.Parse(hostName)

Resolving an IP address from DNS in C# [duplicate]

This question already has answers here:
Can't parse domain into IP in C#?
(6 answers)
Closed 9 years ago.
I am trying to make a TCP socket connection to an IP address. I can do this by directly parsing an IP address like this:
IPAddress ipAddress = IPAddress.Parse("192.168.1.123");
IPEndPoint remoteEP = new IPEndPoint(ipAddress, 80);
// Create a TCP/IP socket.
Socket sender = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); // This works!
However, I cannot figure out how to divine this IP address from a DNS string. I've tried every combination of the following:
IPAddress ipAddress = Dns.Resolve("www.mydns.org"); // No dice
IPAddress ipAddress = Dns.GetHostEntry("www.mydns.org"); // Nada
IPAddress ipAddress = IPAddress.Parse(Dns.Resolve("www.mydns.org")); // So many errors...
IPAddress ipAddress = IPAddress.Parse(Dns.Resolve("www.mydns.org").toString()); // WTh is this attempt anyway?
Would any of you kind souls have a tip to help me squeeze an IPAddress out of a DNS?

foreach (IPAddress ip in Dns.GetHostAddresses("www.mydns.org"))
{
Console.WriteLine(ip.ToString());
}
or simply IPAddress address = Dns.GetHostAddresses("www.mydns.org")[0]; if you want the first one only.

I've got a very neat extension method for just that!
I takes into account that an IPV6 may be returned as the first address in the list of addresses returned by the DNS class and allows you to "favor" an IPV6 or IPV4 on the result. Here is the fully documented class (only with the pertinent method for this case for reasons of brevity):
using System;
using System.Linq;
using System.Net;
using System.Net.Sockets;
/// <summary>
/// Basic helper methods around networking objects (IPAddress, IpEndPoint, Socket, etc.)
/// </summary>
public static class NetworkingExtensions
{
/// <summary>
/// Converts a string representing a host name or address to its <see cref="IPAddress"/> representation,
/// optionally opting to return a IpV6 address (defaults to IpV4)
/// </summary>
/// <param name="hostNameOrAddress">Host name or address to convert into an <see cref="IPAddress"/></param>
/// <param name="favorIpV6">When <code>true</code> will return an IpV6 address whenever available, otherwise
/// returns an IpV4 address instead.</param>
/// <returns>The <see cref="IPAddress"/> represented by <paramref name="hostNameOrAddress"/> in either IpV4 or
/// IpV6 (when available) format depending on <paramref name="favorIpV6"/></returns>
public static IPAddress ToIPAddress(this string hostNameOrAddress, bool favorIpV6=false)
{
var favoredFamily = favorIpV6 ? AddressFamily.InterNetworkV6 : AddressFamily.InterNetwork;
var addrs = Dns.GetHostAddresses(hostNameOrAddress);
return addrs.FirstOrDefault(addr => addr.AddressFamily == favoredFamily)
??
addrs.FirstOrDefault();
}
}
Don't forget to put this class inside a namespace! :-)
Now you can simply do this:
var server = "http://simpax.com.br".ToIPAddress();
var blog = "http://simpax.codax.com.br".ToIPAddress();
var google = "google.com.br".ToIPAddress();
var ipv6Google = "google.com.br".ToIPAddress(true); // if available will be an IPV6

IPHostEntry entry = Dns.GetHostEntry(hostNameOrAddress: "www.google.com");
foreach (IPAddress addr in entry.AddressList)
{
// connect, on sucess call 'break'
}
Simply enumerate address by calling GetHostEntry, on sucess break the loop

IPv4 remote address in WCF

Related to How to get the IP address of a WCF remote endpoint?
I am using this code to retrieve the remote IP address when a workflow method is invoked:
private static string GetRemoteIP()
{
var oc = OperationContext.Current;
var mp = oc.IncomingMessageProperties;
var remp = mp[RemoteEndpointMessageProperty.Name] as RemoteEndpointMessageProperty;
return remp == null ? "(unknown)" : remp.Address;
}
However, the address I get back is "::1". I don't want the IPv6 address, I want the IPv4 one (127.0.0.1) - any way of forcing this?

No, I don't think so. You basically just read out a property set by the client at the time of the call. Your only option would be to instruct the client (through some config) to use IPv4 instead of IPv6 at all times (i.e. turn off IPv6 all together).
I'm not aware of any WCF setting to enforce that - you'd have to dig into the network stack and see if there's any way to make it use IPv4 addresses instead of IPv6.

You're seeing ::1 because you're connecting to the service by resolving the name "localhost" instead of addressing it as "127.0.0.1". Modern versions of Windows that have the IPv6 stack enabled will use IPv6 first.
You can disable the IPv6 stack, but that's roughly the same as making like an ostrich and sticking your head in the sand. IPv6 is here, and people are using it on their networks, so your application should be prepared to support it.

The workaround proposed by Murat will not work.
The MSDN says - if you pass the IP address to the GetHostAddresses method this address is returned in an array without querying the DNS.
To get it working you will need to query for the host name first, using GetHostEntry method. And then, using the host name, use GetHostAddresses. However, even the GetHostEntry may have the list of addresses that will be enough for you.

Here is a workaround: (You can store the values in a hashtable to avoid multiple DNS operations)
static string GetClientIP()
{
var context = OperationContext.Current;
var mp = context.IncomingMessageProperties;
var propName = RemoteEndpointMessageProperty.Name;
var prop = (RemoteEndpointMessageProperty) mp[propName];
string remoteIP = prop.Address;
if(remoteIP.IndexOf(":") > -1)
{
IPAddress[] addresses = Dns.GetHostAddresses(remoteIP);
for (int i = 0; i < addresses.Length; i++)
{
if(addresses[i].ToString().IndexOf(".")>-1)
return addresses[i].ToString();
}
return remoteIP;
}
else
{
return remoteIP;
}
}

You could use AddressFamily.InterNetwork == address.AddressFamily and AddressFamily.InterNetworkV6 as a test instead of looking for ":" or "." in the addresses strings.