For help, advice and discussion about stuff not related to aviation. Play nice: no religion, no politics and no axe grinding please.
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By Colonel Panic
#1845542
Understanding ssh & keeping a Terminal session open

I have managed to get my oil tank monitoring to work again, but the following surprises me. (NB: I don't think that I have sorted the "re-start the feed on power restoration", but that is for another day.)

I now notice that if I log in via ssh and type
Code: Select allsudo ./jjbwatchman.sh
the feed starts, and continues. But if I close the Terminal window - even after _many_ hours - the feed stops. I had thought that Terminal & ssh just provided a window in to what was happening, but it appears to be doing more than that. #confused
By Colonel Panic
#1845605
Several months ago Colonel Panic wrote:Ugh, sorry to do this ... but why does Linux have to be so unintuitive!


I found this recent video from Linus Torvalds quite interesting on "Why desktop Linux sucks"; seems to me that there are strong parallels with the (alleged) problems associated with Android.

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By stevelup
FLYER Club Member  FLYER Club Member
#1845628
Colonel Panic wrote:Perfect - sorted. Need to re-educate myself about how Terminal isn't just a "window" on what the RPi is doing.


Your memory is failing you. I already explained nohup (what it is, and how to use it) on this very thread at the end of Jan!
By Colonel Panic
#1845682
You did, and I did remember after being reminded :pale:

What I hadn't realised fully was how ssh isn't "just a window on the RPi" (like, say TeamViewer on another Mac is), but an instruction through it stops if you quit the session. Hopefully I will remember this is 6 months time :D
Flyin'Dutch' liked this
By Colonel Panic
#1848401
PoE specs

Two quick questions ...

    Please don't shout at me for being dim, but if a CCTV camera calls for "Power: 12vDC / PoE(802.3af)", can I use a PoE injector that has an output of "24vDC, 0.5A(0.5A)"? Will the camera just "pull" 12V, or will I fry it?

    If I plug the camera in to a PoE switch (Unifi US-8-60W), which states "Max PoE Wattage per port: 15.4W, Power method: 48vDC, Max 2A" will it work or will I fry the camera?

TIA :pale:
User avatar
By rikur_
FLYER Club Member  FLYER Club Member
#1848416
Wait for @stevelup to give you the definitive answer, but my reading of that is that it will work from either a 12v DC connection, or a 802.3.af (~48v) connection - but not the 24v PoE injector.
i.e. the PoE switch shouldn't fry it.
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By Paul_Sengupta
FLYER Club Member  FLYER Club Member
#1848535
Give us the details of the camera. It sounds like it'll either take a 12V DC input separately to the PoE or it'll take PoE. Is PoE "standard" at 48V? If that's the case, it should work ok with that, but to be sure we'd need to see the full camera spec and what connections it has.
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By stevelup
FLYER Club Member  FLYER Club Member
#1848989
You've had the right answer already. Those cameras will work either with a PoE switch or a proper PoE injector (48V).

That injector you have lying around is probably a Ubiquiti one which is non-standard. Nothing will fry, but it almost certainly won't work.

I have spare 48V injectors lying around if you need one.
By Colonel Panic
#1853859
Understanding LAN IP address ranges

My LAN network uses 192.168.2.1-255, and all is well. So why would a new Reolink NVR show up as 172.16.25.1, and the four cameras connected to it show up as 172.16.25.3/5/6/7 within my Unifi USG's dashboard?

Earlier today I changed the IP address of the NVR to 192.168.2.114, both within the Unifi dashboard and also within the NVR's own GUI. I also restarted the NVR & the USG to try to promulgate these changes. Ditto the cameras. But this doesn't seem to have "stuck".

What am I mis-understanding?

TIA
Image
By riverrock
FLYER Club Member  FLYER Club Member
#1853982
There isn't a rule on which to use, but you can't mix and match.
It's only really an issue when you start trying to connect different networks together (VPN or bridge).

> 192.168.0.0 - 192.168.255.255 (65,536 IP addresses) (typically a small home or stand alone office)
> 172.16.0.0 - 172.31.255.255 (1,048,576 IP addresses) (typically a stand alone data center)
> 169.254.0.0 - 169.254.255.255 (65,536 IP addresses) (typically random auto-assigned to self when no DHCP server present)
> 10.0.0.0 - 10.255.255.255 (16,777,216 IP addresses) (typically a corporate LAN)
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