Windows 7 does not accept broadcasts from ip address 0.0.0.1

we have little network devices which are shipped with IP address 0.0.0.1 to ensure that they never collide with any other device in their new environment (thus none of the 10.x.x.x, 172.16.x.x or 192.168.x.x ranges) until configuration. DHCP is no solution since there might be no DHCP server in the field.

The devices would listen to UDP broadcasts and an开发者_如何学Goswer with broadcasts until they are given their new IP address this way.

This worked fine with Windows XP - but sucks with Windows 7: the config program does not receive the answer packets from the devices which still have 0.0.0.1. Wireshark sees the packets, then they are dumped by the system.

Question: Is there any reason (RFC?) that actually prohibits using this address in a local environment? Or is it just MS that was overcautious? Where can I read why they treat this address "invalid"? Which ranges are really "invalid" now, too?

Any idea of a workaround on the PC side (Win 7)?

I know that it is not recommended to use 0.xxx addresses for work places, but for this very reason - having a not-used address - it works perfectly.

Edit: there is a device out there called "Netburner" which might have faced the similar issue, according to their forum. See: http://forum.embeddedethernet.com/viewtopic.php?f=5&t=612&p=2198 Does - by coincidence - anybody know some background information?

It sounds as if your configuration application is listening for broadcast packets on all network interfaces and expecting to receive packets from foreign subnets.

That should not work - the OS should only pass-on broadcast packets from the subnets each network interface is on, not from all subnets on the same physical (e.g. Ethernet) segment. I am reasonably certain that doing otherwise is broken behaviour WRT the IP protocol.

The are two ways to deal with this:

• Make sure that your network interface has an IP address in the target subnet. You can have more than one IP addresses for each network card, so that should not interfere with normal network operations.

• Configure or modify you application to use raw sockets, like Wireshark. Keep in mind, however, that this overrides all normal checks and balances and should be avoided, since it can cause behaviour that is almost impossible to diagnose - which is why it is frowned upon by meny network administrators.

Can you you add new routing table entries to Windows machines easily? Windows has to know which interface to use when routing a broadcast packet to the 0.0.0.x network.

The Unix machines I'm familiar with have a routing table that maps network/netmask entries to either gateways or interfaces (if the network is a local network). The local network (192.168.0.0/16 for my home network) gets sent to interface eth0. Everything else 0.0.0.0/0 gets sent to a specific gateway machine 192.168.0.1.

If my machine sent a UDP broadcast message to network 0.0.0.0/24 (in other words, UDP broadcast sent to 0.0.0.255, then my machine would forward the packet to the gateway machine (which it can look up via arp). The switches in the middle wouldn't propagate the packet to other network devices, because the MAC address is set.

If my machine had another routing entry for 0.0.0.0/24 to the local interface, then my machine would send the packet on the wire using an ethernet broadcast group, and the switches would forward the packet to all connections. (Yay! Just like hubs in the 90s! :)

So I figure you need to add a routing entry for 0.0.0.0/24 to your client machines, so that they can properly address the broadcast packet.