Receiving local broadcast packet sent from a "supernet"

My question is for Linux, in C.

Say host A on subnet /16 is sending a broadcast UDP packet. (ie. by broadcasting to xxx.xxx.255.255)

Is there a way for host B on the sub-subnet with a subnet mask /24 to receive that broadcast?

My test program on host B waits on the right port but does not receive anything if A sends to xxx.xxx.255.255. But it does when xxx.xxx.xxx.255 is us开发者_StackOverflow社区ed.

Moreover I have constraints that 1. I cannot change network config, 2. Legacy program running on Host A doing that cannot be changed either.

Thanks!

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No, and it sounds like your network is configured incorrectly.

You cannot have overlapping networks. Either you have a /16 network, and every host within that /16 uses 255.255.0.0 as the netmask; or you have broken it up into smaller networks, in which case each smaller network will have its own netmask and broadcast address.

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try broadcasting to the subnet that computer is on. x.x.?.255

e.g.

ip is 24.234.123.?
broadcast to 24.234.123.255

since the computer is locked to the subnet /24 it will be locked only to ip's in its range.

and its broadcast is within its range.