perl udp broadcast

[rosen4o]

Hi There, I'm truing to send udp broadcast packet from network interface. When I have default gateway then the packet is routed from this interface which is from gateway network. The other solution is when I add from interface to the packet. But I need to send packet from interface which doesn't have assigned ip address. Any idea how to do that? I'm using linux.

[Anonymous Monk]

need to send packet from interface which doesn't have assigned ip address

You can't communicate without an IP (like talking without a mouth).

?node_id=3989;HIT=UDP%20broad;re=N

[Khen1950fx]

Your English isn't very clear, but I think that you're looking for something like IO::Socket::INET. Here's an example of a server and a client by zentara that uses IO::Socket::INET.

[rowdog]

Are you saying that you get your address and gateway from a DHCP server and that you would like to send a UDP packet to the broadcast address? If so, then sure, check out IO::Socket::INET.

If you want to do the above, but get the packet routed past the gateway, well, most routers won't pass a broadcast packet along so you're probably out of luck unless you can configure your gateway to pass it along, which is generally a bad idea.

[rosen4o]

I want to make little broadcast config application. Clients will broadcast their ip addresses periodically server will listen for packets. The problem comes from there that I can't send broadcast packets without to have ip address on the network interface. Maybe Net::RawIP can help me???

[rowdog]

Sounds like a reverse DHCP. Since you don't have an IP address, you'll have to send at a lower level. I haven't used Perl for much below the layer of IP but if Net::RawIP doesn't work out for you Net::Frame and Net::Frame::Layer::Eth or Net::Write might be useful.

[rosen4o]

Thanks I will try

[rosen4o]

This modules have many dependencies. If I use this code I can send packet if even doesn't have gateway. Is there any way to send it on specific interface without ip on it.

$sock = new IO::Socket::INET(
LocalAddr => '192.168.0.138',
PeerAddr => '255.255.255.255',
PeerPort => '9190', # Port the udp server listens on
Proto => 'udp',
Broadcast => 1 # Not sure if this is needed, I know the sockopt is
) || die "[ERROR] $!\n";
$sock->sockopt(SO_BROADCAST, 1);
print $sock "test\n";

[Corion]

UDP is based on IP, so you can't send an UDP packet without an IP. Or rather, you'll have to construct a raw packet and send it on the raw interface.