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Programmatically Changing IP address, Domain Name Server and Gateways

, 15 Jul 2004 CPOL
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This article shows how we can change the IP address with corresponding subnet mask, gateway with corresponding metric, and DNS of local computer through programming.

Sample Image - testreg.gif

Introduction

Please forgive me for some bad English grammar I am going to use in this article, really I am very bad at English. Now, let me explain about this article.

This article helps you to change the IP address, DNS and gateway dynamically through programming.

Basically, the secret weapon for changing these are hidden in the registry. These two registry keys hold the key for that.

  1. HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft \Windows\CurrentVersion\NetworkCards

    Holds the information about all the cards installed on you computer in its subkeys that start from 1 to last.

  2. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet \Services\TcpIp\Parameters
\Interfaces \%s

Here %s is card name you got from above key.

Here is the screen shot for key #2 showing all the Regeditor structure:

Sample image

Now I'll explain each and every function used in this project. Basically, the IP address and gateways are stored in registry in REG_MULTI_SZ format, so I have created different functions for each type of network.

  BOOL ViewNumberOfCard(CStringArray *arCard, 
                           CStringArray *arCardName);

  //this function send the current status in program
  BOOL ViewGateway(CStringArray &card,CStringArray  &ipaddress);
  void ViewGateWayMetrics(CStringArray &card,CStringArray  &ipaddress);
  BOOL ViewSubnetMask(CStringArray &card,CStringArray  &ipaddress);
  BOOL ViewDNSSubnet (CStringArray &card,CStringArray  &ipaddress,int var);
  BOOL ViewIPAddress (CStringArray &card,CStringArray  &ipaddress);
        
  ////function change the cuurnet status
  
  BOOL ChangeGateway(CString card,CStringArray  &ipaddress);
  BOOL ChangeGateWayMetrics(CString card,CStringArray  &ipaddress);
  BOOL ChangeDNSSubnet (CString card,CStringArray  &ipaddress,int ver);
  BOOL ChangeSubnetMask(CString card,CStringArray  &ipaddress);
  BOOL ChangeIpAddress (CString card,CStringArray  &ipaddress);

OK, now I'll explain to you the working of each function. Basically, each function's working is same but each is deal with different network identities.

BOOL ViewNumberOfCard(CStringArray *arCard,CStringArray *arCardName);

This function will return card number with the card name.

//this function send the current status in program

BOOL ViewGateway(CStringArray &card,CStringArray  &ipaddress);
void ViewGateWayMetrics(CStringArray &card,CStringArray  &ipaddress);
BOOL ViewSubnetMask(CStringArray &card,CStringArray  &ipaddress);
BOOL ViewDNSSubnet (CStringArray &card,CStringArray  &ipaddress,int var);
BOOL ViewIPAddress (CStringArray &card,CStringArray  &ipaddress);

Working of all functions are same. First parameter returns corresponding card number with its IP address except in ViewDNSSubnet in which the third variable is used to retrieve the DNS from single user version.

////function change the current status

BOOL ChangeGateway(CString card,CStringArray  &ipaddress);
BOOL ChangeGateWayMetrics(CString card,CStringArray  &ipaddress);
BOOL ChangeDNSSubnet (CString card,CStringArray  &ipaddress,int ver);
BOOL ChangeSubnetMask(CString card,CStringArray  &ipaddress);
BOOL ChangeIpAddress (CString card,CStringArray  &ipaddress);

Working of these functions are also the same. They change the network identity of the computer.

Also, here is a small code for helping you view the IP address and to retrieve the value from the complicated REG_MULTI_SZ format:

BOOL CNMPNetworkChange::ViewIPAddress(CStringArray &card, 
                                        CStringArray  &ipaddress)
 {
  //declare some useful variable
   char *szValue=new char[600];
   CString str;
   DWORD pdw=599;
   int i=0;
   //registry variable come from header file ATLBASE.h 
   CRegKey key;

   for(int flag=1;flag<=100;flag++)
   {   
    szValue[0]=NULL;
    pdw=599;
    key.Close();
    //this flag variable check number of network card in computer
    
    str.Format("SOFTWARE\\Microsoft\\Windows NT
                \\CurrentVersion\\NetworkCards\\%d",flag);  

    if(key.Open(HKEY_LOCAL_MACHINE,str,KEY_READ)==ERROR_SUCCESS)
      {
     key.QueryValue(szValue,"ServiceName",&pdw);
     key.Close();

     str.Format("SYSTEM\\CurrentControlSet\\Services
           \\TcpIp\\Parameters\\Interfaces\\%s",szValue);

     if(key.Open(HKEY_LOCAL_MACHINE,str,KEY_READ)!=ERROR_SUCCESS)
     {

     }

   char *szValue1=new char[2000];
     pdw=1999;

     //querry the REG_MULTI_SZ value
     RegQueryValueEx(key.m_hKey,
                    TEXT("IPAddress"),
                    NULL,
                    NULL,
                    (LPBYTE)szValue1,
                    &pdw);

     char *temp=new char[20];
     int j=0;
    str.Format("%d",flag);
    //NOw this is logic of retriving the value from the REG_MULTI_SZ

     for(i=0;i<(int)pdw;i++)
     {
      if(szValue1[i]!=NULL)
      {
       temp[j++]=szValue1[i];
      }
      else
      {
        temp[j]=NULL;
       if(strcmp(temp,"")!=0)
       {
        card.Add(str);
        ipaddress.Add(temp);
       }
       j=0;
      }
     }
     delete[] temp;
     delete[] szValue1;
     key.Close();
    }
   }
   delete[] szValue;
   return TRUE;
 }

I think I explained much. If the user encounters some problem while using my s/w, feel free to mail to me because while solving your problem, I'll learn something new.

Special thanks to my project team mates Mr. Rakesh Pant and Mr. Jatin Kumar.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

ThatsAlok
Software Developer (Senior)
India India
He used to have biography here Smile | :) , but now he will hire someone (for free offcourse Big Grin | :-D ), Who writes his biography on his behalf Smile | :)
 
He is Great Fan of Mr. Johan Rosengren (his idol),Lim Bio Liong, Nishant S and DavidCrow and Believes that, he will EXCEL in his life by following there steps!!!
 

For good 8 years he was Visual CPP MSMVP!

Comments and Discussions

 
GeneralThe WIN32 way: use IPHELPER Pinmemberahz17-Dec-05 5:53 
GeneralRe: The WIN32 way: use IPHELPER PinmemberRoland_W25-Jan-06 22:38 

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