site_archiver@lists.apple.com Delivered-To: Macnetworkprog@lists.apple.com Thread-index: AcmfV4Y+keDtDDdzPUCPZlD3HNKvTA== Thread-topic: How to broadcast to 255.255.255.255 on non-default interface User-agent: Microsoft-Entourage/12.15.0.081119 I'm trying to do a UDP broadcast to the 255.255.255.255 address to all interfaces. The problem is that the broadcast will only be sent out the default(primary) interface. Nothing ever shows up on the other interface. As far as I can tell this is how the IP layer will route it even though the socket was bound to the address of the interface. I can broadcast to a limited address (ie. 192.168.50.255) and it will be sent out the other interface(not default). Here's the info on the two interfaces.. eth0: 10.0.1.20 netmask 255.255.255.0 eth1: 192.168.50.2 netmask 255.255.255.0 eth0 is set as the primary in the network config panel and needs to stay this way as it's the path to the internet. eth1 is the interface to a network of devices that all respond to broadcasts with their addresses in the reply. The devices live in the 10.x.x.x (netmask 255.0.0.0) realm. Work-arounds (that are less than desirable to instruct a user though) 1. Manually change the address of eth1 to be in the 10.x.x.x subnet and broadcast to 10.255.255.255 in the app 2. Change the service order manually and disable access to the internet while connected to the devices and broadcast to 255.255.255.255 3. Create another service attached to eth1 with an address on the 10.x.x.x subnet and broadcast to 10.255.255.255 No. 3 is the best I've got so far, but I'd have to automate this process somehow which would also require admin privileges *frown*. Ideally I'd like to force the broadcast to route down the interface of the user's discretion, but that *force* part is what I'm missing. I was hoping that the MSG_DONTROUTE of send() and sendto() would be the magic, but when sending I get notified that the network is unreachable. How does a DHCP server do this. It must be able to send broadcasts down a chosen interface other than the default one. Any help is greatly appreciated. -Craig _______________________________________________ Do not post admin requests to the list. They will be ignored. Macnetworkprog mailing list (Macnetworkprog@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/macnetworkprog/site_archiver%40lists.... This email sent to site_archiver@lists.apple.com