dhcpcd-discuss

On 24/07/2020 13:46, Stefano Cappa wrote:
> How many times dhcpcd calls my custom hook? I suppose multiple times, or am I wrong?
> If dhcpcd calls the hook multiple times and $if_up is always true, I'll restart 
> my ntp service many times.
> To prevent this, is it right to compare "old_" and "new_" ntp_servers variables 
> to understand if something is changed to decide if I should reboot systemd or not?
> Obviously, as you suggested, I should also check if the variable is empty.

This is what the dhcpcd ntp hook script does.

> All this discussion is about my worries about runtime/live changes of the router 
> configuration. Because, if I change NTP on the router, I expect that my device 
> with dhcpcd will always receive and update the new NTP via DHCP packet. But 
> obviously, I don't want to restart NTP daemon if there are no real reasons to do it.

Yes

> "The answer simply is, you just don't know." I absolutely agree with this and I 
> have to trust in dhcpcd.
> But my question was more about to find a commercial router that I can buy 
> without spending too much money to try my configuration.

Why not setup a VM and install your own NTP server? Then just set it's IP 
address in the DHCP message from your DHCP server which may or may not be on the 
same machine.

> Because at the moment I don't have any physical router that can set NTP via 
> DHCP. I found only routers able to set the local time, but not an ip address. 
> Also searching on the web I found only some professional Cisco routers, but not 
> something cheaper to buy. I'm really surprised that this feature is so uncommon 
> on domestic routers.
> If you have this information, can you suggest, also privately, the model of 
> router available on the market that can let me try this feature on a real 
> network? At least, to check if what I've done is really working, because now I'm 
> simulating everything and I don't really trust what I've done.

I'm not going to do your market research for you :)

I generally roll my own router - I currently use an EdgeRouter LITE re-flashed 
with NetBSD which runs dnsmsaq and NTPd.

Roy