Getting local IP

LonelyStar · 2004-08-26T17:20:36

Hi everybody, I am not sure if this question belongs in the Linux or in the Network forum, but I think it is a mire Linux related question: I am trying to determine the IP address of the local computer, so that I can compare it with the IP address a server tells me, my computer has. That way I can find out if I am behind a NAT or not. I tried the following code: char szHostName[128]; char ip[16] = "\0"; struct hostent *pHost; int i; if(gethostname(szHostName, 128) == 0) { pHost = gethostbyname(szHostName); for(i=0; i<pHost->h_length; i++) { if(i > 0) sprintf(ip, "%s.", ip); sprintf(ip, "%s%u", ip, (unsigned int)((unsigned char *)pHost->h_addr_list[0])); } cout << "Address : " << ip << endl; } return 0; The output is Address : 127.0.0.1 I also tried this: char ac[80]; gethostname(ac, sizeof(ac)); cout << "Host name is " << ac << "." << endl; struct hostent *phe = gethostbyname(ac); if (phe == 0) { cerr << "Yow! Bad host lookup." << endl; return 1; } for (int i = 0; phe->h_addr_list != 0; ++i) { struct in_addr addr; memcpy(&addr, phe->h_addr_list, sizeof(struct in_addr)); cout << "Address " << i << ": " << inet_ntoa(addr) << endl; } And get: Host name is Sam. Address 0: 127.0.0.1 But the IP address of eth0 is 10.10.152.49! How could my programm find out this address??? Thanks! Nathan

Everything Unix Technical

Started by LonelyStar August 26, 2004 12:17 PM

9 comments, last by LonelyStar 20 years, 2 months ago

LonelyStar

Author

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August 26, 2004 05:20 PM

OK, cool, that seems like a good way too!
But I am not connection to another machine. I called connect on an UDP socket and as far as I know that only sets the default address to which packeages are send when "send" is called.
But thanks a lot for your code!!! I think I will do it your way.

Getting local IP

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Getting local IP

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