Linux: /etc/network/interfaces, 'broadcast'

Cerulean

Cerulean

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What is the 'broadcast' under an interface (such as eth0)? The example config shows 192.168.1.0 for broadcast. According to a not-as-straight-forward Google search, 'broadcast' is known as the Broadcast ID.

What is that? I have two external static IP addresses, and I was able to get all the information I needed (including for 'network'), except for 'broadcast' because the support tech. was not sure what "broadcast ID" is or was (and neither am I). What am I supposed to set it as? Is it a required line?
 
its normally ending with 255 I think

so 192.168.1.255 would be for a 192.168.1.x network. packets sent to 192.168.1.255 are sent to all hosts

Its needed for ARP and possible uPNP device discovery.

External IPs should not need a broadcast address
 
The broadcast is the last IP of the subnet. So for 192.168.1.0/24, the broadcast is 192.168.1.255.
 
Jay_oasis said:
its normally enfing with 255 I think

so 192.168.1.255 would be for a 192.168.1.x network. packets sent to 192.168.1.255 are sent to all hosts
Click to expand...

We posted at the same time with nearly the same info, lol.

255 isn't always the broadcast, it depends on the network. So 192.168.1.0/30, the broadcast is 192.168.1.3.
 
Subnet is 255.255.255.128, and our static IPs have a CIDR of /25.

*looks up subnet calc*

Should be x.x.x.126 I think (based on your responses about 'broadcast' being the last IP of the subnet range).
 
Ok, I just made a massive fail in this thread. The tech gave me the broadcast. It's the "network" he didn't know.

/facepalm
 
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