Subject: Re: [44net] Strange Broadcasts... From: Jeroen Massar jeroen@massar.ch Date: 06/11/2015 09:03 PM

To: AMPRNet working group 44net@hamradio.ucsd.edu

...

Forget about this; it's just syntax. Who cares if we have to have hundreds of P2P interfaces instead of a single P2MP?

ntpd cares about it and also the Linux and FreeBSD kernels.

ISC ntpd listens on each interface automatically, hence after ~200 interfaces it breaks as it runs out of file descriptors (each interface gets a separate socket as it uses it that way to be able to properly select the interface to reply to packets on that interface).

I know about that problem! Silly ntpd listens on a separate socket for every address, instead of just listening on a wildcard socket. It caused havoc on our gateway because it has over 200 addresses assigned to a dummy0 interface, used by an EchoLink proxy farm running on the machine.

Fortunately in recent versions of ntpd it can be solved by config like this:

interface ignore all interface listen lo interface listen eth1 interface listen tun0 interface listen tunl0

i.e. you can direct ntpd what interfaces to watch and to ignore the rest.

I think it would be better when it listened on 0.0.0.0 instead (of course you CAN set the source address of outgoing packets on a wildcard socket, at least in Linux you can), but I saw there already has been a heated debate about that on the mailinglist so I chose not to suggest that and use the abovementioned workaround.

Rob