[info] Docker

[publicarray]

G'day

I just wanted to mention that I have create a simple docker file for rsntp: https://github.com/publicarray/docker-rsntp

Feel free to use it https://hub.docker.com/r/publicarray/rsntp

Keep up the good time!

[mlichvar]

That's great. Thanks!

[Artoria2e5]

To expand on your theme of using iptables: there's no rate limit on rsntp, but we can still survive misconfigured clients if we get iptables to do the limiting. For example, we can do...

-A INPUT -m udp -p udp --dport 123 -m statistic --mode random --probability 0.25 -j ACCEPT
-A INPUT -m udp -p udp --dport 123 -m hashlimit --hashlimit-above 8/minute --hashlimit-burst 8 --hashlimit-mode srcip --hashlimit-srcmask 28 --hashlimit-name ntp --hashlimit-htable-max 131072 --hashlimit-htable-expire 64000 -j DROP

to mimick chrony's defaults for ratelimit (inverval 3 burst 8 leak 2). It's not exact (8/min is not the same as 0.125/s), but that's the closest I could get.

I usually add a harsher

-A INPUT -m udp -p udp --dport 123 -m hashlimit --hashlimit-above 64/second --hashlimit-burst 64 --hashlimit-mode srcip --hashlimit-srcmask 28 --hashlimit-name ntp1 --hashlimit-htable-max 131072 --hashlimit-htable-expire 4000 -j DROP

to the beginning, because I am selfish and value my bandwidth dollar over availablity.