Getting service port with getservbyname()

karas · 09-14-2007, 07:54 AM

Hi,
the following code

Code:

int main()
{
	struct servent* se = getservbyname("telnet", "tcp");
	printf("%d\n", se->s_port);
}

prints as port number 5888 but in /etc/services this protocol has default port 23. And generally, getting port value with this function for any service differs from the values written in /etc/services. Why is that happening?
Thanks

robwhit · 09-14-2007, 08:39 AM

try converting it to host byte order.

Code:

printf("%d\n", ntohs(se->s_port));

karas · 09-15-2007, 05:16 PM

It works, thanks.

09-14-2007, 07:54 AM	#1
karas Registered User Join Date: Jan 2006 Location: Belgrade Posts: 72	Getting service port with getservbyname() Hi, the following code Code: int main() { struct servent* se = getservbyname("telnet", "tcp"); printf("%d\n", se->s_port); } prints as port number 5888 but in /etc/services this protocol has default port 23. And generally, getting port value with this function for any service differs from the values written in /etc/services. Why is that happening? Thanks
karas is offline

09-14-2007, 08:39 AM	#2
robwhit Registered User Join Date: Oct 2001 Posts: 2,110	try converting it to host byte order. Code: printf("%d\n", ntohs(se->s_port));
robwhit is offline

09-15-2007, 05:16 PM	#3
karas Registered User Join Date: Jan 2006 Location: Belgrade Posts: 72	It works, thanks.
karas is offline

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