Very Computer

Hi,

Don't know whether this is the most appriopriate forum to ask, but I'll risk
it :)

I'm developping a linux networking app. (kernel 2.2.0+), using the default
sockets implementation offered by linux. I'm using C, and TCP/IP.

Two questions (somewhat overlapping, but I'm not sure if it is necessary to
know all of 2 to know 1):
1. how can I (=what is the best way to) know if a given IPv4 address is the
IP address of one of the local network interfaces (, or that is is not a
local IP address).
To get this information I do not want to make a TCP connection to any remote
machine (because I am not necessarily able to do so at the time I want this
to know), I do not want to peek in '/proc', and I do not want to run a
program from my program (like ifconfig).

2. how can I create a list of all local IP addresses.

Thanks,

--
Vik

have a look at the meaning of NETMASK.  basically, any ip address that
is identical to yours in the area identified by the netmask is on the
local network interface.

Quote:>2. how can I create a list of all local IP addresses.

what exactly do you mean?  any ip address with the same NETMASKed
portion is a local ip address (exept for the net and the broadcast
address).  if you want to know all ip addresses that have an interface
assigned to them, i think there is a way to ask your dns server for a
list.  all ip addresses that are currently connected?  no way except
going to the net and find out (the other machines have to be
cooperative, though)

hs

Quote:> have a look at the meaning of NETMASK.  basically, any ip address that
> is identical to yours in the area identified by the netmask is on the
> local network interface.

I think you misunderstood. My program does not know what the running host's
IP address is. I just want to find out without calling a program. Is such a
thing possible using socket programming?

Quote:> if (ioctl(s,SIOCGIFCONF,&ifconf)==-1) {

Thanks a lot!

_Exactly_ what I was looking for :)

Kind regards,

--
Vik