Prusa Mini NTP server used  

RE: Prusa Mini NTP server used

Ended up getting out my sharktap.

Looks like the Prusa mini uses a hard coded NTP server IP 195.113.144.238. I saw no DNS lookup performed.

For those curious, at least within the 1st 5minutes of power on, there are exactly 4 packets that come out/in the Prusa mini

1) DHCP request sent to the typical broadcast address
2) DHCP response received from my router
3) NTP request sent to 195.113.144.238
4) NTP response received from 195.113.144.238

Absolutely no other traffic like "Phoning Home"

RE: Prusa Mini NTP server used

From the source, looks like it is some Czech server "Czech CESNET NTP server tak.cesnet.cz"

See https://github.com/prusa3d/Prusa-Firmware-Buddy/blob/master/lib/WUI/sntp/sntp_client.c#L13

I have not verified with wireshark.

RE: Prusa Mini NTP server used

Posted by: @bobcousins

From the source, looks like it is some Czech server "Czech CESNET NTP server tak.cesnet.cz"

Prusa is going to be charged with DDOSing their ISP then! Bad form. They'd better fix that soon, maybe point to OpenNTP servers. 

RE: Prusa Mini NTP server used

Ahh good old tik.cesnet.cz and tak.cesnet.cz 😀 I used them back in ... nineties? for my home Linux server and still occasionally put them if I need NTP server quick. They are academic network, I would not worry about their ISP as they are the ISP for universities and science academies in Czech Republic. They started the internet here.

RE: Prusa Mini NTP server used

Posted by: @d0ug

Does anyone here know which NTP server the Prusa Mini is using to pull it's NTP time? I have my own GPS to NTP server here at home built with an ESP8266 and would like to point the printer at it by redirecting at my router whatever domain it is hitting to my own NTP server. I dont see any facility within the settings to configure the NTP server used.

If no one already knows, i'll pull out my sharktap setup and sniff the printer's traffic with wireshark. Just feeling lazy =) and in the middle of a many hour print, not sure how frequently it polls, if not only once at bootup.

Already tried looking in my router for active connections coming from the Mini's IP and there currently are none.

Sorry, only just spotted this tread. This was pretty much the same thing that I did when I first connected my mini to the Network.

As you say its is a very quiet device, does its DHCP and NTP sync on boot. I thought it also sent some uPNP packets. But it was a few weeks ago, so I am not 100% sure.

Port scan showed not surprise ports open, which is always good.

I blocked NTP at the router, as that was the only way I could get the Mini to tell me the Time remaining. Not the end time.

RE: Prusa Mini NTP server used

I actually wish it would show both the estimated clock time that it will end, and the hours/min/sec remaining, or a setting to toggle between the two. I have already noticed that over time it seems the clock drifts, though hard to really tell since I can't see what time the mini thinks it actually is. For instance a print I recently did the mini said would end at 5:49p, but it was actually 5:55p on my cell phone when it completed.

Clock drifting is expected when time keeping is done entirely in software, with no RTC to keep the time in check. I have seen it myself in time related ESP8266/ESP32 projects

Two of my projects are clock related. One being a 75HUB LED wall panel Tetris clock and the other is an off the shelf nixie clock kit that accepts GPS NEMA input. For the Nixie clock I have an ESP8266 that polls NTP time then generates the time related serial NEMA data stream that would come off a GPS receiver. For both of these I have the ESPs polling the NTP server once per minute to keep the time in check, otherwise they drift wildly, i've seen minutes per day when the time is kept purely in software with no NTP updates.

RE: Prusa Mini NTP server used

I think the Mini firmware polls the NTP server every hour. It uses the "simple" API, so it just sets the local clock according to the time from the server.

The time remaining is  a guesstimate, so is likely to bounce around a bit. I think people notice when the end time changes, but would not notice if the time remaining changes.

For my clock projects I have used a DS3231, which keeps pretty good time for the cost. The RTC module in a CPU is still only as good as the external clock, the typical 32 kHz crystals are not very good.

RE:

How to set up NTP redirect in air gapped networks:

https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/3523#issuecomment-1858816452