How to get a user s client IP address in ASP NET

Question

We have Request UserHostAddress to get the IP address in ASP NET  but this is usually the user s ISP s IP address  not exactly the user s machine IP address who for example clicked a link  How can I get the real IP Address   For example  in a Stack Overflow user profile it is   Last account activity  4 hours ago from 86 123 127 8   but my machine IP address is a bit different  How does Stack Overflow get this address    In some web systems there is an IP address check for some purposes  For example  with a certain IP address  for every 24 hours can the user just have only 5 clicks on download links  This IP address should be unique  not for an ISP that has a huge range of clients or Internet users   Did I understand well

User · Answer

What you can do is store the router IP of your user and also the forwarded IP and try to make it reliable using both the IPs  External Public and Internal Private   But again after some days client may be assigned new internal IP from router but it will be more reliable

User · Answer

Often you will want to know the IP address of someone visiting your website  While ASP NET has several ways to do this one of the best ways we ve seen is by using the  HTTP X FORWARDED FOR  of the ServerVariables collection   Here s why     Sometimes your visitors are behind either a proxy server or a router and the standard Request UserHostAddress only captures the IP address of the proxy server or router  When this is the case the user s IP address is then stored in the server variable   HTTP X FORWARDED FOR     So what we want to do is first check  HTTP X FORWARDED FOR  and if that is empty we then simply return ServerVariables  REMOTE ADDR     While this method is not foolproof  it can lead to better results  Below is the ASP NET code in VB NET  taken from James Crowley s blog post  Gotcha  HTTP X FORWARDED FOR returns multiple IP addresses   C    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        VB NET  Public Shared Function GetIPAddress   As String     Dim context As System Web HttpContext   System Web HttpContext Current     Dim sIPAddress As String   context Request ServerVariables  HTTP X FORWARDED FOR       If String IsNullOrEmpty sIPAddress  Then         Return context Request ServerVariables  REMOTE ADDR       Else         Dim ipArray As String     sIPAddress Split New  Char        c           Return ipArray 0      End If End Function

User · Answer

Combining the answers from  Tony and  mangokun  I have created the following extension method   public static class RequestExtensions       public static string GetIPAddress this HttpRequest Request                if  Request Headers  CF-CONNECTING-IP      null  return Request Headers  CF-CONNECTING-IP   ToString             if  Request ServerVariables  HTTP X FORWARDED FOR      null                        string ipAddress   Request ServerVariables  HTTP X FORWARDED FOR                 if   string IsNullOrEmpty ipAddress                                 string   addresses   ipAddress Split                       if  addresses Length    0                                        return addresses 0                                                      return Request UserHostAddress

User · Answer

I think I should share my experience with you all  Well I see in some situations REMOTE ADDR will NOT get you what you are looking for  For instance  if you have a Load Balancer behind the scene and if you are trying to get the Client s IP then you will be in trouble  I checked it with my IP masking software plus I also checked with my colleagues being in different continents  So here is my solution   When I want to know the IP of a client  I try to pick every possible evidence so I could determine if they are unique   Here I found another sever-var that could help you all if you want to get exact IP of the client side  so I am using   HTTP X CLUSTER CLIENT IP  HTTP X CLUSTER CLIENT IP always gets you the exact IP of the client  In any case if its not giving you the value  you should then look for HTTP X FORWARDED FOR as it is the second best candidate to get you the client IP and then the REMOTE ADDR var which may or may not return you the IP but to me having all these three is what I find the best thing to monitor them   I hope this helps some guys

User · Answer

use this  Dns GetHostEntry Dns GetHostName

User · Answer

You can use   System Net Dns GetHostEntry System Net Dns GetHostName    AddressList GetValue 0  ToString

User · Answer

All of the responses so far take into account the non-standardized  but very common  X-Forwarded-For header  There is a standardized Forwarded header which is a little more difficult to parse out  Some examples are as follows   Forwarded  for   gazonk  Forwarded  For   2001 db8 cafe  17  4711  Forwarded  for 192 0 2 60 proto http by 203 0 113 43 Forwarded  for 192 0 2 43  for 198 51 100 17   I have written a class that takes both of these headers into account when determining a client s IP address   using System  using System Web   namespace Util       public static class IP               public static string GetIPAddress                         return GetIPAddress new HttpRequestWrapper HttpContext Current Request                       internal static string GetIPAddress HttpRequestBase request                           handle standardized  Forwarded  header             string forwarded   request Headers  Forwarded                if   String IsNullOrEmpty forwarded                                 foreach  string segment in forwarded Split      0  Split                                             string   pair   segment Trim   Split                           if  pair Length    2  amp  amp  pair 0  Equals  for   StringComparison OrdinalIgnoreCase                                                 string ip   pair 1  Trim                                   IPv6 addresses are always enclosed in square brackets                         int left   ip IndexOf       right   ip IndexOf                               if  left    0  amp  amp  right  gt  0                                                        return ip Substring 1  right - 1                                                         strip port of IPv4 addresses                         int colon   ip IndexOf                               if  colon    -1                                                        return ip Substring 0  colon                                                         this will return IPv4   unknown   and obfuscated addresses                         return ip                                                                        handle non-standardized  X-Forwarded-For  header             string xForwardedFor   request Headers  X-Forwarded-For                if   String IsNullOrEmpty xForwardedFor                                 return xForwardedFor Split      0                              return request UserHostAddress                      Below are some unit tests that I used to validate my solution   using System Collections Specialized  using System Web  using Microsoft VisualStudio TestTools UnitTesting   namespace UtilTests        TestClass      public class IPTests                TestMethod          public void TestForwardedObfuscated                         var request   new HttpRequestMock  for    gazonk                  Assert AreEqual   gazonk   Util IP GetIPAddress request                        TestMethod          public void TestForwardedIPv6                         var request   new HttpRequestMock  For    2001 db8 cafe  17  4711                  Assert AreEqual  2001 db8 cafe  17   Util IP GetIPAddress request                        TestMethod          public void TestForwardedIPv4                         var request   new HttpRequestMock  for 192 0 2 60 proto http by 203 0 113 43                Assert AreEqual  192 0 2 60   Util IP GetIPAddress request                        TestMethod          public void TestForwardedIPv4WithPort                         var request   new HttpRequestMock  for 192 0 2 60 443 proto http by 203 0 113 43                Assert AreEqual  192 0 2 60   Util IP GetIPAddress request                        TestMethod          public void TestForwardedMultiple                         var request   new HttpRequestMock  for 192 0 2 43  for 198 51 100 17                Assert AreEqual  192 0 2 43   Util IP GetIPAddress request                         public class HttpRequestMock   HttpRequestBase               private NameValueCollection headers   new NameValueCollection             public HttpRequestMock string forwarded                        headers  Forwarded     forwarded                     public override NameValueCollection Headers                       get   return this headers

User · Answer

IP addresses are part of the Network layer in the  seven-layer stack   The Network layer can do whatever it wants to do with the IP address  That s what happens with a proxy server  NAT  relay  or whatever   The Application layer should not depend on the IP address in any way  In particular  an IP Address is not meant to be an identifier of anything other than the idenfitier of one end of a network connection  As soon as a connection is closed   you should expect the IP address  of the same user  to change

User · Answer

use in ashx file  public string getIP HttpContext c        string ips   c Request ServerVariables  HTTP X FORWARDED FOR        if   string IsNullOrEmpty ips                 return ips Split      0             return c Request ServerVariables  REMOTE ADDR

User · Answer

string IP   HttpContext Current Request Params  HTTP CLIENT IP      HttpContext Current Request UserHostAddress

User · Answer

In NuGet package install Microsoft AspNetCore HttpOverrides Then try  public class ClientDeviceInfo               private readonly IHttpContextAccessor httpAccessor           public ClientDeviceInfo IHttpContextAccessor httpAccessor                        this httpAccessor   httpAccessor                     public string GetClientLocalIpAddress                         return httpAccessor HttpContext Connection LocalIpAddress ToString                       public string GetClientRemoteIpAddress                         return httpAccessor HttpContext Connection RemoteIpAddress ToString                       public string GetClientLocalPort                         return httpAccessor HttpContext Connection LocalPort ToString                       public string GetClientRemotePort                         return httpAccessor HttpContext Connection RemotePort ToString

User · Answer

Its easy Try it   var remoteIpAddress   Request HttpContext Connection RemoteIpAddress    just it

User · Answer

Try   using System Net   public static string GetIpAddress       Get IP Address       string ip                IPHostEntry ipEntry   Dns GetHostEntry GetCompCode         IPAddress   addr   ipEntry AddressList      ip   addr 2  ToString        return ip    public static string GetCompCode       Get Computer Name          string strHostName           strHostName   Dns GetHostName        return strHostName

User · Answer

As others have said you can t do what you are asking  If you describe the problem you are trying to solve maybe someone can help    E g     are you trying to uniquely identify your users   Could you use a cookie  or the session ID perhaps instead of the IP address    Edit The address you see on the server shouldn t be the ISP s address  as you say that would be a huge range  The address for a home user on broadband will be the address at their router  so every device inside the house will appear on the outside to be the same  but the router uses NAT to ensure that traffic is routed to each device correctly  For users accessing from an office environment the address may well be the same for all users  Sites that use IP address for ID run the risk of getting it very wrong - the examples you give are good ones and they often fail  For example my office is in the UK  the breakout point  where I  appear  to be on the internet  is in another country where our main IT facility is  so from my office my IP address appears to be not in the UK  For this reason I can t access UK only web content  such as the BBC iPlayer   At any given time there would be hundreds  or even thousands  of people at my company who appear to be accessing the web from the same IP address   When you are writing server code you can never be sure what the IP address you see is referring to  Some users like it this way  Some people deliberately use a proxy or VPN to further confound you   When you say your machine address is different to the IP address shown on StackOverflow  how are you finding out your machine address  If you are just looking locally using ipconfig or something like that I would expect it to be different for the reasons I outlined above  If you want to double check what the outside world thinks have a look at whatismyipaddress com    This Wikipedia link on NAT will provide you some background on this

User · Answer

UPDATE  Thanks to Bruno Lopes  If several ip addresses could come then need to use this method       private string GetUserIP                 string ipList   Request ServerVariables  HTTP X FORWARDED FOR             if   string IsNullOrEmpty ipList                         return ipList Split      0                      return Request ServerVariables  REMOTE ADDR

User · Answer

If you are using CloudFlare  you can try this Extension Method   public static class IPhelper       public static string GetIPAddress this HttpRequest Request                if  Request Headers  CF-CONNECTING-IP      null  return Request Headers  CF-CONNECTING-IP   ToString             if  Request ServerVariables  HTTP X FORWARDED FOR      null  return Request ServerVariables  HTTP X FORWARDED FOR   ToString             return Request UserHostAddress            then  string IPAddress   Request GetIPAddress

User · Answer

What else do you consider the user IP address  If you want the IP address of the network adapter  I m afraid there s no possible way to do it in a Web app  If your user is behind NAT or other stuff  you can t get the IP either   Update  While there are Web sites that use IP to limit the user  like rapidshare   they don t work correctly in NAT environments

User · Answer

If is c  see this way  is very simple  string clientIp    Request ServerVariables  HTTP X FORWARDED FOR                          Request ServerVariables  REMOTE ADDR    Split      0  Trim

User · Answer

public static class Utility       public static string GetClientIP this System Web UI Page page                string  ipList   page Request Headers  CF-CONNECTING-IP   ToString            if   string IsNullOrWhiteSpace  ipList                         return  ipList Split      0  Trim                      else                        ipList   page Request ServerVariables  HTTP X CLUSTER CLIENT IP                if   string IsNullOrWhiteSpace  ipList                                 return  ipList Split      0  Trim                              else                                ipList   page Request ServerVariables  HTTP X FORWARDED FOR                    if   string IsNullOrWhiteSpace  ipList                                         return  ipList Split      0  Trim                                      else                                       return page Request ServerVariables  REMOTE ADDR   ToString   Trim                                                        Use   string  ip   this GetClientIP

User · Answer

Hello guys Most of the codes you will find will return you server ip address not client ip address  however this code returns correct client ip address Give it a try  For More info just check this  https   www youtube com watch v Nkf37DsxYjI  for getting your local ip address using javascript you can use put this code inside your script tag   lt script gt      var RTCPeerConnection     window RTCPeerConnection           window webkitRTCPeerConnection    window mozRTCPeerConnection            if  RTCPeerConnection   function                   var rtc   new RTCPeerConnection   iceServers                      if  1    window mozRTCPeerConnection                           rtc createDataChannel       reliable  false                                   rtc onicecandidate   function  evt                      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                        document getElementById  list   textContent   displayAddrs join   or perhaps        n a                                function grepSDP sdp                     var hosts                        sdp split   r n   forEach function  line                          if   line indexOf  a candidate                                  var parts   line split                                       addr   parts 4                                type   parts 7                            if  type      host   updateDisplay addr                          else if   line indexOf  c                                      var parts   line split                                    addr   parts 2                            updateDisplay addr                                                                             else                         document getElementById  list   innerHTML     lt code gt ifconfig  grep inet   grep -v inet6   cut -d      -f2   tail -n1 lt  code gt                 document getElementById  list   nextSibling textContent    In Chrome and Firefox your IP should display automatically  by the power of WebRTCskull                     lt  script gt   lt body gt   lt div id  list  gt  lt  div gt   lt  body gt    and For getting your public ip address you can use put this code inside your script tag    function getIP json        document write  My public IP address is     json ip          lt script type  application javascript  src  https   api ipify org format jsonp amp callback getIP  gt  lt  script gt

[c#] How to get a user's client IP address in ASP.NET?

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