Intro
I was having trouble with one of my new F5 clusters. I thought I’d be clever and add two new F5’s to the existing cluster, and then remove the old members when everything looked good.
But the device groups somehow remembered the old servers, even though they weren’t in the device groups. Eventually I could not even sync the two new servers together.
Here’s a concise summary of the steps which worked, taken from this article:
Hi Manuel, do you try to setup a sync-failover device-group containing three units? To establish device trust I would recommend to force two units into offline state. Remove the machines from the existing sync-failover device-group (repeat on each machine if required) and delete the sync-failover device-group. Now reset the device trust on all machines. Next step will be to use the active machine to add both offline machines as peers. Now all three units should show up in each machine´s device list. On the active unit create a new device-group of type sync-failover with network failover enabled. Add all machines to the new device-group. This will be synced to all machines and you can release them from forced offline. Time for the initial sync now. Thanks, Stephan
I get a little confused about sync-only vs sync-failover. That difference is clearly discussed there as well:
“Sync-only” will not allow to synchronize LTM configurations.
To synchronize an LTM config all units need to belong to the same “sync-failover” device-group.
I had afraid and ignorant of the need to reset device trust. For good measure I deleted all device groups. Then this procedure seems to leave me with an auto-created datasync-global-dg (sync-only). Since there was no sync-failover group I manually created one I called sync-LTM-configs. Another auto-created, sync-only group is the device_trust_group. So I see three device groups in all when I am on the sync page, but only two when I am on the device group page.
Conclusion
I had afraid and ignorant of the need to reset device trust in cleaning up an F5 cluster with old and new members. But once I did that and followed the recipe above, I was good to go.
Intro
I’m trying out the system-supplied postfix on a SLES system. i had been using sendmail but there doesn’t seem to be any development on that software.
Some commands I needed right away
Well, right away I had thousands of queued messages so I needed a way to make sense of what was happening.
For these commands to make sense you need to know that I am running a second postfix configuraiton out of /etc/postfixEXT.
Display the queue
postqueue -c /etc/postfixEXT -p
postqueue -c /etc/postfixEXT -p
Force delivery from the queue
postqueue -c /etc/postfixEXT -f
postqueue -c /etc/postfixEXT -f
List one email in detail
postcat -vq -c /etc/postfixEXT QUEUEID
postcat -vq -c /etc/postfixEXT QUEUEID
Delete one email
postsuper -c /etc/postfixEXT -d QUEUEID
postsuper -c /etc/postfixEXT -d QUEUEID
Put mail on hold
postsuper -c /etc/postfixEXT -h ALL|QUEUEID
postsuper -c /etc/postfixEXT -h ALL|QUEUEID
Release mail form hold
postsuper -c /etc/postfixEXT -H ALL|QUEUEID
postsuper -c /etc/postfixEXT -H ALL|QUEUEID
How to force delivery of a single message
This command is not documented anywhere – because it doesn’t exist so you have to get creative. If you have the luxury of halting all email for a few seconds simply do this:
Display the queue to find the queue ID of the email you want to force delivery of
postqueue -c /etc/postfixEXT -p
postqueue -c /etc/postfixEXT -p
Put all mail on hold
postsuper -c /etc/postfixEXT -h ALL
postsuper -c /etc/postfixEXT -h ALL
Now release the hold on that one email
postsuper -c /etc/postfixEXT -H QUEUEID
postsuper -c /etc/postfixEXT -H QUEUEID
QUEUEID is, of course, the queue id .e.g., F2A1A27891E, of the email in question.
Look for what happened
Check your mail log’s last lines in /var/log/mail
Revert back to normal running
postsuper -c /etc/postfixEXT -H ALL
postsuper -c /etc/postfixEXT -H ALL
Since mail is store-and-forward and not real time, you can do these steps, quickly, even on a production system and no one will be the wiser if you are pretty quick. Probably takes two minutes even for a slow typer.
How to run multiple listeners
I didn’t want to disturb the system-installed postfix too much. I would let it “have” the loopback address, 127.0.0.1, leaving me the other IPs for my relay config to listen on. I added these lines to /etc/postfix/main.cf
service postfix start starts up the local postfix plus my relay. Grep the process table for either master or postfix to see. However, to be honest, service postfix stop does not kill all processes. So I always end up killing one of the master processes by hand. Update: postmulti -p stop does the trick to kill all. There is also a status or start option instead of stop.
Sendmail to Postfix migration tips
This could be a separate post but I am too lazy to do that.
What happens to the access file? I kept the name of the file access but just list all the IPs, one per line, without any further arguments, to permit just those IPs relay access. In my main.cf I have a line like this to tie it together:
mynetworks = /etc/postfixEXT/access
mynetworks = /etc/postfixEXT/access
Note that there is no hashed or .db version of this file any longer, unlike in the sendmail case.
I haven’t run this in two years. I just revived my scripts today, resuscitated an old Raspberry Pi, and voila, it’s pretty much good to go. When I moved to my new server in 2020 some of the scripts got mangled. I’m trying to fix those. For the record, I use the continuousaudio.sh script + ffmpegwireless6.sh mentioned below. That gives me a live audio stream on YouTube with a solid gray video. I’m researching further enhancements and will post those if I ever manage to pull them off.
What I would like to do is to have it interpret and respond to a couple audio commands as in “start recording” and “stop recording”. Now whether or not I can pull that off is an entirely different story. But you’ll never know if you don’t try…
Intro
I’ve been looking at this off and on for awhile now. I finally made a breakthrough this week and started to generate some decent live streams on my YouTube channel, after a lot of misfires.
Note this is applicable for Raspbian Stretch Lite on a Raspberry Pi 3. However, I firmly believe it will work just the same for regular Raspbian Stretch.
There’s a lot of wrong, misleading or outdated information out there on the Internet. Hopefully this will help others to avoid wasting as much time as I had to do.
This project was prompted by my desire to make a more generalized fishcam! Described in this post, my original fishcam implementation – and I realized this form the get-go – has very limited applicability because very few people are in a position to have their own AWS server. And if you don’t know what you’re doing, please don’t run your own server – the security exposure is too great.
So I eventually realized that maybe I could generalize what I had done – essentially remove the dependency on the AWS server – by utilizing Youtube Live Streaming. And, I believe I was right. It’s still a work in progress however.
The command – ffmpeg
I was playing with ffmpeg. The version I am playing with now comes with Raspbian – no need to compile like in the bad old days. ffmpeg -version shows the version to be 3.2.12. I get the impression that its capabilities are version-dependent, so that’s why this information is particularly relevant in this case.
The details
In some of my early attempts I was getting a lot of this (looking at YouTube Live Dashboard)
Dashboard When stream is not quite right
Another attempt
Video works, audio like driving in a car with the windows down. For the record, the command was this:
It is not so pretty to use that hardware address for the Logitech webcam device. Where do you see that hardware address? Either a lsusb or a ls /dev/snd/by-id shows addresses of sound devices. I found a simpler substitute:
With this audio's, not too bad, video's a bit choppy. Google reports the stream quality as OK, check resolution.
So I fix the bandwidth (which was a typo in the above, but one with an interesting result). I set video bandwidth to -b:v 1200k. Now the video is OK once again, but the audio is choppy again! Weird. bandwidth is about 1100 kbps.
This version had OK video and OK audio
But I keep getting inconsistent results! Sometimes a setting will work, and then I come back to it and it doesn’t. Weird.
Part of the problem is that I have no idea what I’m doing and I didn’t know when i was watching a livestream vs a recorded (on-demand) one! I have since learned to look for the little red Live button. A picture is worth 10^3 words in this case.
[Pic no longer available – try the thousand words instead!]
Observed used bandwidth is about 1450 kbits/sec. But still lots of dropped packets. Here is what ffmpeg reports. I’m not sure yet what most of it means:
That is working great – showing the video as before but now with a silent audio track.
Increase Video Quality
Here I’ve increased video quality a tad by requesting more fps (10) and making qscale 0 (which means highest quality). https://www.youtube.com/watch?v=5Aall8w4Y3E
What is observed to happen is that ffmpeg actually chooses 15 fps rather than 30. I’ve read it decides what it is able to do, so maybe that’s the highest fps it can deliver. Video is pretty smooth (See my Livestream link in references if I happen to have it running. Otherwise I will create a video link.) No drops are recorded, but the sound, though not terrible, has some pops. Bandwidth used is about 1900 kbps. So this is definitely my best effort yet. YouTube complains about the unsupported video size of 640×480, but it permits it and I don’t think it’s a real problem.
Reducing bandwidth
This one is pretty good overall. I have no idea why lowering the audio bandwidth might help. It’s counter intuitive. But video motion is not bad – just a tad blurred. I guess q=23. Audio has good patches and not-as good patches. Not as good spots are staticky, not washboard bad. Total bandwidth used is about 611 kbps. So a great compromise. Why does raising the video bandwidth lower the audio quality? I have no idea… The settings below worked for maybe 20 minutes, then YouTube said this Video is unavailable. I at least found out something about that. That shows a problem with the player, not (for once) your stream. so since I’m only concentrating on the stream, that’s good news. So actually it delivered good sound for three hours straight with a few staticky spots.
The audio is creepily sensitive, easily picking up conversations in adjacent rooms.
But then I monkeyed around with the settings, got the washboard sound, came back to this one – a known good – and got washboard audio! What the heck? Why isn’t it consistent?? No idea… Maybe it’s the player that gets messed up?? Now I’m running it again and it’s OK.
Bandwidth talk
It’s important to talk about bandwidth if you haven’t given this any real thought. You have to have a halfway decent broadband connection for this to work, you see? If you have a mid-speed cable modem or DSL, you have much lower upload than download speeds, and you may not be able to pull off a reliable 1.5 mbps upload. For those lucky enough to have Verizon FIOS this is a non-issue. But for instance in the high school where I volunteer they have throttled the guest WiFi network to such an extent that achieving this modest 1.5 mbps is going to present a real challenge. If you rely on a phone’s hotspot you will also probably be unable to get such a speed. So I may look at more ways to reduce the bandwidth required in the future.
And between YouTube and your ISP, it just seems the whole thing about live video broadcasting seems, well, delicate. Stream Health varies between oK, to Excellent to not receiving – all during the same streaming session! It often takes five minutes or so for the stream to appear to be working.
Comparing two webcams
Someone picked up a really cheap DI Chatcam at Microcenter in Paterson. I think that’s Digital Innovations Chatcam. It’s cute. It has a big clip on the end and shines white LEDs when it’s on. I think it was about $12. With the exact same ffmpeg settings (with audio suppressed), the quality was not nearly as good as with the Logitech webcam. Here’s a link to the YouTube video made with the chatcam: https://www.youtube.com/watch?v=OI2IRV1i__k. Note that it has a ministereo plug for audio. I didn;’t even plug it in now that I know how to suppress audio!
I need to re-run this test now that I know how to increase the video quality.
A breakthrough: publishing an audio-only stream to YouTube
Besides covering your lens with tape, what’s a software way to blacken the video and concentrate on producing the best audio I wondered?
The above gives me good audio, and a sold gray background. I love it – for recording band practice or whatever. The breakthrough is that we can avoid wasting cpu cycles on processing input video but just use a color. Thanks Stackoverflow for the tip. Used bandwidth is about 150 kbs – basically nothing! YouTube Dsahboard complains:
OK Video output low
The stream's current bitrate (138.00 Kbps) is lower than the recommended bitrate.
We recommend that you use a stream bitrate of 2500 Kbps.
OK Video output low
The stream's current bitrate (138.00 Kbps) is lower than the recommended bitrate.
We recommend that you use a stream bitrate of 2500 Kbps.
But of course that is bogus because that assumes we are trying to put out a rich 1280×720 video, which we are not.
Then eventually YouTube has this complaint:
Bad Bad video settings
Please use a keyframe frequency of four seconds or less. Currently, keyframes are not being sent often enough, which will cause buffering.
The current keyframe frequency is 8.5 seconds. Note that ingestion errors can cause incorrect GOP (group of pictures) sizes.
Bad Bad video settings
Please use a keyframe frequency of four seconds or less. Currently, keyframes are not being sent often enough, which will cause buffering.
The current keyframe frequency is 8.5 seconds. Note that ingestion errors can cause incorrect GOP (group of pictures) sizes.
Yet the stream does not seem to suffer in any noticeable way from this problem.
For good measure, we add a few extra arguments allow us to remove the keyframes warning. We need to use the -g parameter (group of pictures) at about twice our frame rate, plus, maybe, a no-scenecut argument. Here’s that version.
Actual fps is 25, quality is 26 and bitrate is 145 kbps. But audio quality is good. I hear white noise in the background, but hey, this isn’t exactly professional equipment we’re working with. But this is a great solution for an audio-only recording that goes straight out to YouTube. stability is also good.
The load average is high – 3.6 (use top to watch it), almost all of it taken by ffmpeg. So it appears ffmpeg is really working it to produce this audio stream. That makes me suspect it just gets overwhelmed when it’s an audio + video stream? Because I never did find setting swhich produced good quality for both…
Switch to Wifi and Yet another problem surfaces
It seems that with this livestreaming project everything that should just work doesn’t! I had been doing all my testing used wired Ethernet connection and WiFi disabled. anticipating a portable solution, I tried it using WiFi and no Ethernet cable. And washboard audio reappeared. quite often ffmpeg hangs as well. I tried a zillion experiments and now my revelation is that essentially, though we tried to minimize and trivialize video, we were probably still overwhelming the CPU. So I reasoned that these actions will make the load easier on the CPU, without compromising the audio quality:
– reduce frame per second dramatically
– reduce key frames
– reduce video size
And…yes, these things in combination really did help and permit me to run over WiFi now. This version, put inside a script I call ffmpegwireless6.sh, looks like this:
It doesn’t start consistently, however, but if you run it enough times it’ll go. So, to provide reliability I also scripted around these deficiencies: I decided to just keep trying to start up ffmpegwireless.sh until I jhave evidence it’s working. I call that script masterwireless.sh:
#!/bin/sh
# DrJ 5/2019
LOG="ff.log"`date +%m-%d-%y:%H:%M`
while /bin/true; do
nohup ./ffmpegwireless6.sh$LOG 2>&1 &
sleep 7
# want s.th like
#Frame= 84 fps= 11 q=16.0 size= 43kB time=00:00:07.50 bitrate= 47.1kbits/s dup=0 drop=431 speed=0.991x
#Frame= 84 fps= 11 q=16.0 size= 43kB time=00:00:07.50 bitrate= 47.1kbits/s dup=0 drop=431 speed= 1x
FFOUT=`tail -1 $LOG`
echo "last line is $FFOUT"
KB=`echo $FFOUT|awk '{print $(NF-4)}'`
echo "orig KB: $KB"
KB=`echo $FFOUT|awk '{print $(NF-5)" "$(NF-4)}'|sed 's/kbits.*//'|awk '{print $NF}'`
date
echo "KB is: $KB"
if [ $KB -gt 129 2>/dev/null ]; then
# let our master process exit - we've got a good audio stream
echo "Exiting at *** "`date`
exit
else
# didn't work out: restart and try again
echo "*** Restarting ffmpeg at *** "`date`
pkill -9 -f 'ffmpeg '
fi
done
And…it works great! Very briefly what it does is t that it calls ffmpegwireless6.sh and backgrounds it, then tests its output. It gives it a few seconds to get going, then kills it unless observed streaming bandwidth is a healthy 135 kbps or so (essentially the video takes almost no bandwidth in ffmpegwireless6.sh.)
Putting it all together – livestreaming audio stream to YouTube automatically upon boot up
So I want to drag this thing to a performance and have a confederate with minimal technical know-how start it up. So basically I want it to start livestreaming when the RasPi is powered up. To do that I made this crontab entry (using crontab -e):
It takes a few minutes to get going, but it’s been extremely reliable. It’s started a stream successfully more than 10 times out of 10, at least when I was using my home WiFi connection. When I switched to my phone’s Hotspot, I had one error out of five attempts. The one bad stream just would not start according to Youtube, although per the stats from the log files showed the stream reached the usual good bandwidth. So I don’t know…
And once the stream starts, it is running uninterrupted for hours, anywhere from three to six hours.
Eventually I want to write an API program to automatically check the stream. But before then I may just introduce a refined script which checks the output and restarts ffmpeg when it has ended.
For the record, a typical ff.log file looks like this:
frame= 43 fps= 43 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A dup=0 drop=164 speed= 0x ed= 0x
orig KB: dup=0
Tue 7 May 12:32:08 BST 2019
KB is: dup=0
*** Restarting ffmpeg at *** Tue 7 May 12:32:08 BST 2019
frame= 213 fps= 35 q=8.0 size= 47kB time=00:01:40.91 bitrate= 3.8kbits/s dup=0 drop=847 speed=16.7x
orig KB: 3.8kbits/s
Tue 7 May 12:38:53 BST 2019
KB is: 3
*** Restarting ffmpeg at *** Tue 7 May 12:38:53 BST 2019
illed= 86 fps= 14 q=8.0 size= 104kB time=00:00:06.21 bitrate= 136.7kbits/s dup=0 drop=336 speed=1.03x
orig KB: 136.7kbits/s
Tue 7 May 12:39:00 BST 2019
KB is: 136
Exiting at *** Tue 7 May 12:39:00 BST 2019
frame= 43 fps= 43 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A dup=0 drop=164 speed= 0x ed= 0x
orig KB: dup=0
Tue 7 May 12:32:08 BST 2019
KB is: dup=0
*** Restarting ffmpeg at *** Tue 7 May 12:32:08 BST 2019
frame= 213 fps= 35 q=8.0 size= 47kB time=00:01:40.91 bitrate= 3.8kbits/s dup=0 drop=847 speed=16.7x
orig KB: 3.8kbits/s
Tue 7 May 12:38:53 BST 2019
KB is: 3
*** Restarting ffmpeg at *** Tue 7 May 12:38:53 BST 2019
illed= 86 fps= 14 q=8.0 size= 104kB time=00:00:06.21 bitrate= 136.7kbits/s dup=0 drop=336 speed=1.03x
orig KB: 136.7kbits/s
Tue 7 May 12:39:00 BST 2019
KB is: 136
Exiting at *** Tue 7 May 12:39:00 BST 2019
The other file, which has a name like ff.log05-07-19:12:32, looks more like this:
CPU load average is around 1 or so – much less than before. So I think my ideas are on the right track. Why send 30 frames or whatever each and every second to Youtube just to display a gray screen? The CPU has to work to do that. As long as ffmpeg + Youtube has the intelligence to paste together audio snippets 1/5th second in length five times each second the audio should be taken care of, we’re not playing with the sampling rate or anything – is how I reasoned. Key frames are some sort of overhead as well since they’re extra things ffmpeg has to periodically do. Youtube wants one at least every four seconds. We get really close to that limit by multiplying fps * 3.6 s = 5 * 3.6 = 18 for our group-of-pictures (g) parameter. Previously we were sending a key frame more frequently – every two seconds.
Unreliability
Running this command is still hit-or-miss. As often as not it hangs, and then, if it does not hang, as often as not it often outputs washboard audio. You just <Ctrl-C> to get out of it if hangs, or type “q” if it is producing washboard audio.
Note carefully the bandwidth being used, which ffmpeg reports every second. If it is < 128 kbps, you’re hosed and have washboard audio. If it’s about 135 kbps or higher, you’re good. You don’t even need to waste time fiddling with Youtube’s live_dashboard to listen to it. You get this feedback immediately from ffmpeg. And I intend to use these same observed behaviors to script around ffmpeg’s flakiness and keep restarting it automatically until it is producing a good quality audio stream!
Improved startup
This script, which I call continuousaudio.sh, has some debugging at the beginning, then loops to ensure there is always an audio stream being live-streamed as long as the Pi has power. It has been extremely reliable. I settled on this one for my own purposes.
#!/bin/sh
# drJ 5/2019
LOG="ff.log"`date +%m-%d-%y:%H:%M`
# some info for debugging problems
echo "***********"
date; ip add; ping -c2 8.8.8.8; lsusb
nohup ./ffmpegwireless6.sh > $LOG 2>&1 &
while /bin/true; do
sleep 7
# want s.th like
#Frame= 84 fps= 11 q=16.0 size= 43kB time=00:00:07.50 bitrate= 47.1kbits/s dup=0 drop=431 speed=0.991x
#Frame= 84 fps= 11 q=16.0 size= 43kB time=00:00:07.50 bitrate= 47.1kbits/s dup=0 drop=431 speed= 1x
FFOUT=`tail -1 $LOG`
# next line only for DrJ debugging - lines are long
#echo "last line is $FFOUT"
# use gawk instead of awk to parse long lines
KB=`echo $FFOUT|gawk '{print $(NF-5)" "$(NF-4)}'|sed 's/kbits.*//'|gawk '{print $NF}'`
echo "orig KB: $KB"
KB=$(echo $KB|sed s/\\..*//)
date
echo "KB is: $KB"
if [ $KB -gt 129 2>/dev/null ]; then
# stream looks good - do nothing
echo -n ""
else
# didn't work out: restart and try again
echo "*** Restarting ffmpeg at *** "`date`
pkill -9 -f 'ffmpeg '
nohup ./ffmpegwireless6.sh > $LOG 2>&1 &
fi
done
gawk
Eventually I found I needed to use gawk instead of awk in continuousaudio.sh because the number of fields exceeded the max of roughly 32700 in the line I was parsing. To install gawk:
$ sudo apt-get install gawk
Note it still calls ffmpegwireless6.sh, which I believe I have provided above.
ff.log now looks like this:
**********
Fri 31 May 01:10:59 BST 2019
1: lo: <loopback,up,lower_up> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <no-carrier,broadcast,multicast,up> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
link/ether b8:27:eb:11:fc:06 brd ff:ff:ff:ff:ff:ff
3: wlan0: <broadcast,multicast,up,lower_up> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether b8:27:eb:44:a9:53 brd ff:ff:ff:ff:ff:ff
inet 192.168.1.170/24 brd 192.168.1.255 scope global wlan0
valid_lft forever preferred_lft forever
inet6 fe80::1119:b46a:cb69:63c9/64 scope link
valid_lft forever preferred_lft forever
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=56 time=14.6 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=56 time=17.4 ms
--- 8.8.8.8 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 14.671/16.065/17.460/1.400 ms
Bus 001 Device 004: ID 046d:0825 Logitech, Inc. Webcam C270
Bus 001 Device 005: ID 0424:7800 Standard Microsystems Corp.
Bus 001 Device 003: ID 0424:2514 Standard Microsystems Corp. USB 2.0 Hub
Bus 001 Device 002: ID 0424:2514 Standard Microsystems Corp. USB 2.0 Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
last line is frame= 19 fps=0.0 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A dup=0 drop=69 speed= 0x ^Mframe= 39 fps= 39 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A dup=0 drop=150 speed= 0x ^M
orig KB: dup=0
Fri 31 May 01:11:07 BST 2019
KB is: dup=0
*** Restarting ffmpeg at *** Fri 31 May 01:11:07 BST 2019
last line is frame= 193 fps= 35 q=8.0 size= 100kB time=00:00:27.60 bitrate= 29.6kbits/s dup=0 drop=764 speed=4.99x ^Mframe= 195 fps= 32 q=8.0 size= 108kB time=00:00:28.03 bitrate= 31.4kbits/s dup=0 drop=775 speed=4.65x ^M
orig KB: 31.4
Fri 31 May 01:11:36 BST 2019
KB is: 31
*** Restarting ffmpeg at *** Fri 31 May 01:11:36 BST 2019
...
</broadcast,multicast,up,lower_up></no-carrier,broadcast,multicast,up></loopback,up,lower_up>
**********
Fri 31 May 01:10:59 BST 2019
1: lo: <loopback,up,lower_up> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <no-carrier,broadcast,multicast,up> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
link/ether b8:27:eb:11:fc:06 brd ff:ff:ff:ff:ff:ff
3: wlan0: <broadcast,multicast,up,lower_up> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether b8:27:eb:44:a9:53 brd ff:ff:ff:ff:ff:ff
inet 192.168.1.170/24 brd 192.168.1.255 scope global wlan0
valid_lft forever preferred_lft forever
inet6 fe80::1119:b46a:cb69:63c9/64 scope link
valid_lft forever preferred_lft forever
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=56 time=14.6 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=56 time=17.4 ms
--- 8.8.8.8 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 14.671/16.065/17.460/1.400 ms
Bus 001 Device 004: ID 046d:0825 Logitech, Inc. Webcam C270
Bus 001 Device 005: ID 0424:7800 Standard Microsystems Corp.
Bus 001 Device 003: ID 0424:2514 Standard Microsystems Corp. USB 2.0 Hub
Bus 001 Device 002: ID 0424:2514 Standard Microsystems Corp. USB 2.0 Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
last line is frame= 19 fps=0.0 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A dup=0 drop=69 speed= 0x ^Mframe= 39 fps= 39 q=0.0 size= 0kB time=00:00:00.00 bitrate=N/A dup=0 drop=150 speed= 0x ^M
orig KB: dup=0
Fri 31 May 01:11:07 BST 2019
KB is: dup=0
*** Restarting ffmpeg at *** Fri 31 May 01:11:07 BST 2019
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</broadcast,multicast,up,lower_up></no-carrier,broadcast,multicast,up></loopback,up,lower_up>
Portability
I wanted to record a practice session in my house where no Ethernet port is available (hence I had to get WiFi working, which I believe I have). And I wanted convenience – to not worry about being tethered to the wall by an adapter. So I decided to look for an economical power solution for Raspberry Pi. And I found the ones purpose-built are just too expensive to justify. Pijuice, I’m talking about you. So, really, I realized any old portable USB power stick would work. But I wanted something which could last hours. This Omars 10000 mAh portable USB charger seemed like it would do the trick. $16. And it did. It works great! Two hours later, the LEDs show three bars instead of four, so I think this will supply power for about 8 – 9 hours if I pushed it. And it has the form factor of a smartphone. Ideally I’d want a little on/off switch to avoid plugging/unplugging the power cable, but I didn’t find that as of yet. Maybe there’s a cheap USB cable with that…?
So now I’m not tethered by Ethernet cables nor by a power plug. See where this is progressing? If I use my smartphone’s hotspot I should be able to livestream anywhere I can get a signal, so, for instance, at band performances. I haven’t tried that yet, but I’m hopeful…
YouTube quirks
As previously mentioned (I think)( you need to be enabled for livestreaming. It takes about 24 hours for the approval. I suppose they check to make sure you aren’t a perceived threat.
Recording NPR will give you a copyright violation flag! This has happened to me more than once. I think because they play snippets of new music which are flagged.
Lag. I’ve seen lag time as short as four seconds and maybe as long as 20 seconds or so. It is never instantaneous.
My longest video was 20 hours but the processing took days. In fact I’m not sure it ever completed. So I guess the service falls apart after video lengths of I don’t know, maybe 12 hours or so. So if the desire is to have a continuous security webcam I guess you’ll have to break it into chunks. That’s what I’m thinking about next.
A livestream gets converted to a video by YouTube. That takes awhile – maybe as long as the video length itself is? It slaps a date and time onto the video which you see in your video manager. Unfortunately, using this ffmpeg streaming method it chooses the Pacific standard time timezone. I actually don’t see a simple way to change that either. It may require use of the API, which is beyond what I’m willing to tackle right now. So for me, being in the Eastern time zone all the timestamps are off by three hours, which is kind of annoying.
I wondered, does my livestream ID remain constant, or will it change from broadcast to broadcast? This is important for future use of the API. Well, it changes each time I start a new livestream, even though I use a single (my own) account. Each livestream gets a unique ID which then becomes the ID for the DVR of the video which you can view on-demand. And this ID is the part that changes in the URL of an “unpublished” Youtube video. Say your unpublished livestream is https://www.youtube.com/watch?v=r1wtZwQ-Tk8.
The part of the URL following the v=, namely, in this example, r1wtZwQ-Tk8, is the ID of that video. I would say YouTube tries to be somewhat robust and will not declare your stream has ended until maybe 30 seconds after you have stopped your program. Or maybe it’s a minute or two, I’m not really sure. But I’ve seen that if you restart the streaming quickly enough you’ll be put onto that same livestream. If on the other hand you wait long enough until you see in live_dashboard that stream ended message then It will assign yuo a new video ID if you start your stream again – and don’t forget to reload the live_dashboard page so it can pick up the new ID.
Can you pause a livestream, and later resume, keeping the same URL? In a word, No. Unfortunately. Youtube livestreaming is pretty limited in this way. And how useful would that be? I would use my smartphone to control ffmpeg on my Raspberry Pi to pause our band practice during our lengthy chat breaks, keeping the stream focussed on the music. But no… Not possible.
Logitech webcam quirks
When you pull both video and audio from your Logitech webcam the usage LED illuminates as you’d expect. However, when you’re pulling just the audio, as I show above, that LED does not illuminate, yet it is being used to record all the sounds in its vicinity. I guess I have accidentally and unintentionally stumbled upon a stealth mode, which is a little disconcerting.
Yeti USB microphone quirks
A Yeti mic is extremely sensitive and seems more suited for conversation than music recording in my opinion. Even with the gain all the way down (a must) a loud sound is often distorted. I felt the omni recording mode was the worst in this regard. Stereo recording tolerated sounds better. But, if you want to pikc up every little sound, Yeti is great. More importantly to me, it just worked with the USB settings I used for Logitech. I didn’t have to change a single thing in the way I used ffmpeg.
Testing if the livestream is still running
My idea to do this is to use the YouTube API and periodically test if the livestream is still working. I have read that it can go down for various reason, and there is no goo way from within ffmpeg itself to tell that your stream is no longer live! It will make for a good project to test the livestream using the Google Developer’s API. that will be a separate post if I ever get it working. If it’s found to be down, the Pi could restart ffmpeg, in my thinking.
To do list
I never really perfected the video. Audio I got pretty well.
I will borrow my friend’s Yeti USB mic to see how my audio stream works with a high quality microphone. DONE.
I would like to have a simple external control to turn stream off/ on, whether it is physical or virtual. DONE – see references.
Scripting to monitor stream and restart it once it fails – to have a recording 24×7 like an audio-only security camera. DONE – continuousaudio.sh as documented above.
Pause feature. PARTIALLY DONE.
Conclusion
A Raspberry Pi 3 running Raspbian Stretch Lite is used, along with a Logitech USB webcam, to livestream to YouTube. I showed how to stream video-only with a silent audio track. Then I turned it around and spent most of my time putting a virtual piece of tape over the lens and doing an audio-only livestream. This, after a crap-load of testing and tweaking, eventually began to work in a reliable fashion. Then I showed how to launch the audio-only livestream upon power-up of the Ras Pi.
Since it is a Raspberry Pi, this whole thing lends itself to portability and interesting use cases. With a $17 portable USB battery source and your own Hotspot, you can stream (audio at least) from anywhere you have 4G cell signal – good for recording a banquet, your band performance, or any other long, live event.
I spoke about some of the many quirks of YouTube which are relevant to this project.
YouTube’s links have me confused. If you’re trying to produce a Live Stream you’ll want the live dashboard page to watch it and check its quality as Youtube judges it. Here’s that link: https://www.youtube.com/live_dashboard
Intro
From time-to-time I run my own PKI infrastructure, namely issuing my own certificates from my private root CA. I wanted this root CA to be recognized by Linux utilities running on Suse Linux (SLES), in particular, lftp, which I was trying to use to access an ftps site, which itself is a post for another day. In other words, how do you add a certificate to the certificate store in linux?
The details
Let’s say you have your root certificate in the standard form like this example
Then you can put the certificate inline and within one script install it so that it permanently joins the other root CAs in /etc/ssl/certs with a script like this example:
So the key commands are c_rehash and update-ca-certificates.
Usually SLES is similar to Redhat. But it seems to be different in this case.
This was tested on a SLES 12 SP3 system.
It copies the certificate to /etc/pki/trust/anchors, which by itself is insufficient. Then it creates some kind of hash symlink to the CA file and makes sure that this new certificate doesn’t get wiped out by subsequent system patching. That’s the purpose of the c_rehash and update-ca-certificates commands.
You may also see these hashes and certificates in /etc/ssl/certs. I’m not sure because that’s where I started with all this. But merely dropping the private root CA into /etc/ssl/certs is insufficient, I can say from experience!
Redhat
Redhat is better documented, but for completeness I include it here. You have your inline certificate as in the SLES script, then following that:
...
cd /etc/pki/ca-trust/source/anchors/
echo -e -n $DrJ_Root_CA > DrJ_Root_CA.pem
update-ca-trust
So update-ca-trust is the key command for Redhat Linux. This was tested on Redhat Linux v 7.6.
Fedora v 33
Put your CA file with a .crt file extension into /etc/pki/ca-trust/source/anchors like for Redhat. Run update-ca-trust extract
Debian Linux circa 2023
Put your private CA file into a new directory /usr/share/ca-certificates/extra. Then run sudo dpkg-reconfigure ca-certificates. When prompted with a list of bundles to include make sure to enable your new extra file. Your certificate file needs to end in ‘crt’, not, e.g., ‘cer’. Seems pretty arbitrary to me, but that’s how it is. Of course it has to be standard PEM format. (—BEGIN CERTIFICATE—, etc.).
Python and self-signed certificates or certificates from private CAs
First, note that those are two different cases and need to be handled slightly differently! You may be in need of these measures if you are getting an error in python like this:
urllib3.exceptions.MaxRetryError: HTTPSConnectionPool(host=’www.myhost.local’, port=443): Max retries exceeded with url: / (Caused by SSLError(SSLCertVerificationError(1, ‘[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1123)’)))
Self-signed certificate
If the certificate is truly self-signed, then throw it into a file, let’s call it my-crt.crt in your home directory. Then set an environment variable before running python:
$ export REQUESTS_CA_BUNDLE=~/my-crt.crt
It should now work.
Python reverts to SSL: CERTIFICATE_VERIFY_FAILED after upgrade
So I had it all working. Then the requests package complained about my version of the urllib package. So I upgraded requests with a pip3 –upgrade requests. They the above-mentioned SSL error came back. I noticed that urllib got upgraded when requests was upgraded.
I basically gave up and totally kludged python to fix this. But only after playing with the certifi package etc. So I took the file that is for me the output of certifi.where(): /usr/local/lib/python3.9/site-packages/certifi/cacert.pem
I edited it as root and simply appended by private root CAs to that file. I hated to do it, and I know I should have at least used a virtual env, blah, blah. But at least now my jobs run. By the way, my by-hand tests of urlopen all worked! So it’s just the way some package was using it beyond my control that I had to create this kludge.
Certificate issued from a private CA
I added the private CA to the system CA on Debian with the update-ca-certificates mentioned above. Still no joy. Then I noticed the web server forgot to provide the intermediate certificate so I added that as well. Then, at least, curl began to work. But not python. Strange. For python I still need to define this environment variable:
A second method to handle the case of a certificate issued from a private CA is to bundle the certificate + the intermediate certificate + the private root CA all into a single file, let’s call it my-crt.crt, in your home directory, and define the envirnoment variable same as for the self-signed certificate case:
lftp usage tip with a private CA
If like me you were doing this work in conjunction with running ftps using a certificate signed by a private CA, and want your ftp client, lftp, to not complain about the unrecognized CA, then this tip will help.
After initiating your lftp and sending the username and password, you can send this command
$ ssl:ca-file <path-to-your-private-CA-file>
lftp is so flexible it offers many other ways to do this as well. But this is the one I use.
Conclusion
We show how to add your own root CA to a SLES 12 system. I did not find a good reference for this informaiton anywhere on the Internet.
Intro
There are more articles about running a webcam using Raspberry Pi than Carter has pills. Why bother to create another? This one is unique insofar as I created a fishcam at a school with a restricted network. None of the reference articles I found discussed a way to get your stream onto the Internet except the simplistic approach only available to homeowners of setting up a rule on a home router. Pimylifeup’s article is typical of that genre.
Cooperating third party
To push this webcam out to the Internet when I had no way to allow inbound traffic to the Pi, I realized that I needed a cooperating third party. I looked briefly for a commercial service specializing in this. I did not find one. I suppose there is, but I don’t know. It was actually quicker to stop the search and use my own AWS server as the cooperating third party.
With a cooperating third party what you can do is set up a forwarder from the Pi to cooperating server on the Internet. So that’s what I did. More on that below.
Network restrictions
The Pi was given WiFi access to a school’s bring your own device (BYOD) WiFi. By trial and error (I did not initiate extensive port scans, etc so as to avoid acting like a hacker). I’m familiar with running a almost completely open Guest wireless. This BYOD was not that for some reason unknown to me. One of the first things I tried, to ssh to my server, was not going through. So I knew there were restrictions. Also PING 8.8.8.8 did not work. So ICMP was blocked as well. But web browsing worked, and so did DNS queries. So TCP ports 80 and 443 were allowed, as well as UDP port 53 and possibly TCP port 53. I also observed there was no proxy server involved in the communication. So I simply tested a few other ports that I know are used from time-to-time: 2443 and 8443. If you a hit a server that is not protected by a firewall and not listening on a port that you are testing you will get a Connection reset if your packets are not blocked by a local firewall. I tested with the nc utility. nc -v <my_server> <port> I found a couple open ports this way. Next question: does the network care what protocol is running on that port? They might be looking for https and I was planning to run ssh. For a simple port blocker it might not distinguish what’s going on. That was indeed the case as I was able to run ssh on this non-standard port.
The single most comlicated thing was formulating the appropriate ssh command. I created a dedicated account on my server for this purpose. I embedded the password into the startup script I created using a utility called sshpass. This is not super secure but I wanted something running quickly.
That’s a mouthful! Let’s break it down. sshpass just permits you to run the command and not get a login prompt. It needs to be installed with a sudo apt-get sshpass.
The ssh command sets up a reverse tunnel. I have discussed it in my Access your Raspberry Pi from anywhere blog post, however, some things are different and more complicated here. Here we are setting up port 8443 on my server as the tunnel port which will be accessible to the Internet. It is terminated on the Raspberry Pi’s local port 8081 (the port that the motion package uses for the webcam). We had to use ssh to connect to port 2443 on my server because the school network blocked the standard port 22. Then <PASSWORD>, <USERNAME> and <SERVER_IP> are to be replaced with values specific for my server. I don’t want to publish them.
How I got my server to run ssh on port 2443 as well as port 22
This turned out to be one of the easiest things. It’s good to run your own server… In the file /ets/ssh/sshd_config the listening port was commented out, letting the defaul 22 be in effect. So I uncommented that and added port 2443 like this:
...
# Listen on multiple ports - DrJ 2/1/19
Port 22
Port 2443
...
...
# Listen on multiple ports - DrJ 2/1/19
Port 22
Port 2443
...
Then a sudo service sshd restart and the server listens on both ports for ssh connections!
About the webcam itself
I just followed the Pimylife article as I mentioned. It talks about using the motion package which I’ve never used before. Now in my other posts you’ll see I do stuff with video on Raspberry Pi. In those we had to fight to get the lag time down and keep bandwidth low. I have to say by comparison this motion package is awful. Lag is a couple seconds. There is no sense whatsoever of true video. Just image, wait, next image, wait. No matter the fps setting. I did not have time to switch to a video package that works better. Anyway motion may provide some other advantages we could eventually use. So I just set it to 2 fps (frames per second) since it doesn’t really matter.
The fishcam is at fishcam. It’s not working right now – just showing black. I’m not sure why.
Auto starting
I’ve documented elsewhere the poor man’s way to start something upon initially booting the Pi: stuff the appropriate command into the crontab file.
So you edit your crontab file with a crontab -e. Then you enter
That just sleeps for 20 seconds as your Pi boots up, then establishes the reverse tunnel with that complicated command I explained earlier.
Equipment
Usually thes tutorials start with an equipment list. For me that is the least interesting part. I used a Raspberry Pi 3 running Raspbian. For a camera I used one of my spare USB ELP cameras from my extensive work with USB cameras. While developing the solution I needed a keyboard, mouse and HDMI monitor. Once running, the only thing connected to the Pi is the USB camera and the micro USB power supply.
To be continued…
References and related
A very good guide for your typcial webcam-using-a-Raspberry-Pi situation, i.e., not what I am addressing in my article.
For supplies we love visits to The Micro Center in Paterson, NJ. This past weekend we got Raspberry Pi 3’s for only $29. And the sales tax is only 3% and change.
Intro
In my years at cybersecurity I’ve been sufficiently removed from the action that I’ve rarely been involved in an actual case. Until last night. A friend, whom I’ll call Jute, got a formal complaint about one of his hosted Windows servers.
We have detected multiple hacking attempts from your ip address 47.5.105.236 (Hilfer Online) to access our systems.
>
> Log of attempts:
> – Hack attempt failed at 2019-01-17T14:22:41.6539784Z. Attempted user name: Not specified (typical for port scanners or denial of service attacks), system accessed: RDP, ip address accessed: 158.69.241.92
> – Hack attempt failed at 2019-01-17T14:22:26.2213808Z. Attempted user name: Not specified (typical for port scanners or denial of service attacks), system accessed: RDP, ip address accessed: 158.69.241.92
> – Hack attempt failed at 2019-01-17T14:22:10.6304194Z. Attempted user name: Not specified (typical for port scanners or denial of service attacks), system accessed: RDP, ip address accessed: 158.69.241.92
>
>
> Please investigate this problem.
>
> Sent using IP Ban Pro
> http://ipban.com
Hack, cont.
I’ve changed the IPs to protect the guilty! But I’ve conveyed the specificity of the error reporting. Nice and detailed.
Jute has a Windows Server 2012 at that IP. He is not running a web server, so that conveniently and dramatically narrows the hackable footprint of his server. I ran a port scan and found ports 135, 139 and 3389 open. His provider (which is not AWS) offers a simple firewall which I suggested we use to block ports 135 and 139 which are for Microsoft stuff. He was running it as a local sever so I don’t tihnk he needed it.
Bright idea: use good ole netstat
The breakthrough came when I showed him the poor man’s packet trace:
netstat -an
from a CMD prompt. He ran that and I saw not one but two RDP connections. One we easily identified as his, but the other? It was coming form another IP belonging to the same provider! RDP is easily identified by just looking for the port 3389 connections. Clearly we had caught first-hand an unauthorized user.
I suggested a firewall rule to allow only his Verizon range to connect to server on port 3389. But, I am an enterprise guy, used to stateful firewalls. When we set it up we cut off his RDP session to his own server! Why? I quickly concluded this was amateur hour and a primitive, ip-chains-like stateless firewall. So we have to think about rules for each packet, not for each tcp connection.
Once we put in a rule to block access to ports 135 and 139, we also blocked Jute’s own RP session. So the instructions said once you use the firewall, an implicit DENY ALL is added to the bottom of the rules.
So we needed to add a rule like:
SRC: ANY DST: 47.5.105.236 SRC_PORT: ANY DST_PORT: 3389 ACTION: allow
But his server needs to access web sites. That’s a touch difficult with a stateless firewall. You have to enter the “backwards” rule (outbound traffic is not restricted by firewall):
SRC: ANY DST: 47.5.105.236 SRC_PORT: 443 DST_PORT: ANY ACTION: allow
But he also needs to send smtp email, and look up DNS! This is getting messy, but we can do it:
SRC: ANY DST: 47.5.105.236 SRC_PORT: 25 DST_PORT: ANY ACTION: allow
SRC: ANY DST: 47.5.105.236 SRC_PORT: 53 DST_PORT: ANY ACTION: allow
We looked up the users and saw Administrator and another user Update. We did not recognize Update so he deleted it! And changed the password to Administrator.
Finally we decided we had to bump this hacker.
So we made two rules to allow him but deny the zombie computer:
SRC: 158.69.240.92 DST: 47.5.105.236 SRC_PORT: ANY DST_PORT: 3389 ACTION: reject
SRC: ANY DST: 47.5.105.236 SRC_PORT: ANY DST_PORT: 3389 ACTION: allow
Pyrrhic victory
Success. We bumped that user right out while permitting Jute’s access to continue. The bad news? A new interloper replaced it! 95.216.86.217.
OK. So with another rule we can bump that one too.
Yup. Another success. another interloper jumps on in its place. 124.153.74.29. So we bump that one. But I begin to suspect we are bailing the Titanic with a thimble. It’s amazing. Within seconds a blocked IP is being replaced with a new one.
We need a more sweeping restriction. So we reasoned that Jute will RP from his provider where his IP does not really change.
So we replace
SRC: ANY DST: 47.5.105.236 SRC_PORT: ANY DST_PORT: 3389 ACTION: allow
with
SRC: 175.198.0.0/16 DST: 47.5.105.236 SRC_PORT: ANY DST_PORT: 3389 ACTION: allow
and we also delete the specific reject rules.
But now at this point for some reason the implicit DENY ALL rule stops working. From my server I could do an nc -v 47.5.105.236 3389 and see that that port was open, though it should ont have been. So we have to add a cleanup rule at the bottom:
SRC: ANY DST: 47.5.105.236 SRC_PORT: ANY DST_PORT: ANY ACTION: reject
That did the trick. Port no longer opened.
There still appears in netstat -an listing the last interloper, but I think it just hasn’t been timed out yet. netstat -an also clearly shows (to me anyway) what they were doing: scanning large swaths of the Internet for other vulnerable servers! The tables were filled with SYN-SENT to port 3389 of consecutive IPs! Amazing.
So I think Jute’s server was turned into a zombie which was tasked with recruiting new zombies.
We had finally frozen them out.
Later that night
Late that same night he calls me in a panic. He uses a bunch of downstream servers and that wasn’t working! The downstream servers run on a range of ports 14800 – 15200.
Now bear in mind the provider only permits us 10 firewall rules, so it’s getting kind of tight. But we manage to squeeze in another rule:
SRC: ANY DST: 47.5.105.236 SRC_PORT: 14800-15200 DST_PORT: ANY ACTION: allow
He breathes a sigh of relief because this works! But I want him we are opening a slight hole now. Short term there’s nothing we can do. It’s a small exposure: 400 open ports out of 65000 possible. It should hold him for awile with any luck.
He also tried to apply all updates at my suggestion. I’m still not sure what vulnerability was (is) exploited.
Case: tentaively closed
Our first attempt to use the Windows firewall itself was not initially successful. We may return to it.
Conclusion
We catch a zombie computer totally exploiting RDP on a Windows 2012 server. We knocked it off and it was immediately repaced with another zombie doing the same thing. Their task was to find more zombies to join to the botnet. Inbound firewall rules defined on a stateless firewall were identified which stopped this exploitation while permitting desired traffic. Not so easy when you are limited to 10 firewall rules!
This is a case where IPBAN did us a favor. The system worked as it was supposed to. We got the alert, and acted on it immediately.
I’m not 100% sure which RP vulnerability was exploited. It may have been an RCE – remote code execution not even requiring a valid logon.
Intro
There’s some good and some not-so-good about the new WPI-provided way to handle multiple video streams using a Raspebrry Pi.
ELP Cameras problems
I have bought many of these ELP cameras last year and this. I may be a slow learner, but eventually it dawned on me that the problems I noticed seem to occur because of this model of USB camera. Finally this year we got a chance to explore this further. I got my hands on a Logitech webcam, the kind you use perched on top of a display monitor. We had this set up as a second camera while an ELP camera was the first. Then we rebooted the Pi a whole bunch of times to gather some stats. About 25% of the time there were problems with the ELP over about 10 tries. There were no problems with the Logitech. Here are various problems we’e seen:
– horizontal lines superimposed over image, and image dull
– ghosting, a corner of the field of view is shown in the center of the image
– sometimes the stream never starts and we’re not yet sure if that’s a camera problem or a software problem though I begin to suspect it’s an ELP problem
– one of my pinhole ELP cameras died
So: Logitech webcam is decidedly better.
Power problem
We pay extra attention to the power draw of the Pi. With two cameras attached and a 2 amp or 1.8 amp power supply the red LED power flashes. That is not good. It’s a sign of undervoltage. The command
vcgencmd get_throttled
on your Pi will tell you if there was an undervoltage condition. I see
throttled=0x50005
when using a 2 amp power supply. Note that as far as we can see the camera display itself works just as well. We also have a 3 amp power supply. That produces a solid red led light and vcgencmd get_throttled produces a response of
throttled=0x0,
which probably indicates there were no undervoltage conditions.
The problem we need to avoid for the Pi to attempt to draw more than 2 amps from the regulator. Doing so may shut it down. So we will try to use the Pi along with a powered USB hub.
Bandwidth constraints
We want to be well below 3 mbps for two cameras. How to get there while still providing a useful service. Initially we felt we could run the cameras at 320×240 resolution, 10 fps. But after much playing we found conditions under which we exceed 3 mbps though normally we were below that. I believe that the compressibility of the image is what matters. So a “rich” visudal field with lots of contrasting objects is the least compressible. That vaguely fits our findings as well. So we felt it important to prepare for the worst case. So we actually looked at supported resolutions and settled on 176×144 pixels! It sure isn’t much, agreed, but it’s still helpful. We blow up the images during the display. We use YUYV mode. MJPEG uses considerably more bandwidth.
Refresh trick
With this WPI software, the video streams never display the first time. You have to refresh the page for some reason. We wished to have a one click operation for viewing, however, to minimize the risk of operator error. So we used some old-fashioned META HTML tags to force a page refresh.
Our initial approach was to simply have the web page refresh itself every five seconds. This worked, but caused instability in the video stream itself and given a few minutes, would always crash the video stream. So we came up with an alternative that does a single page refresh. Unfortunately we’re not that conversant in Javascript (I’m sure there’s a way to do this with Javascript) so instead we wrote two HTML pages: a source page with the refresh, and a target page that does not refresh.
And I observed the user agent “Google Hangouts” trying these IPs, but by the FQDN mtalk.google.com (whose resolution must by very dynamic) rather than raw IP:
They all have been used by Google’s Hangouts Meet based on my observation.
If you have an environment which uses proxy authentication, the above IPs do not play well with that. So you’ll need to disable proxy authentication for them for Hangouts Meet to work.
Otherwise you can do the initial connect but will be dropped after about 45 seconds.
Finally, although you can look up each individually and learn of its association to Google, Google’s own documentation is devoid of any references to them. That is unfortunate.
So the IPs in actual use is probably much larger, but these are what I’ve observed over the course of a few days of testing.
What I’ve done
Google is very hard to reach. They only provide indirect means for regular users. So not knowing any insiders I submitted feedback at https://meet.google.com/ which is what they suggest. I provided a detailed description. I doubt they will do anything with my feedback. We’ll see. Update. Correct. Months have passed and they never bothered to get back to me.
Conclusion
Google has an undocumented dependency on a whole set of IPs for hangout Meets to actually work through a proxy which requires authentication. Contacting Google for more information is probably impossible, but I will try.
Intro
My old car I decided finally needed a touch of Bluetooth connectivity. But how to do it without spending a fortune?
The details
I found this amazingly inexpensive gadget on Amazon that describes itself as follows: Handsfree Call Car Charger,Wireless Bluetooth FM Transmitter Radio Receiver&Mp3 Music Stereo Adapter,Dual USB Port Charger Compatible for All Smartphones,Samsung Galaxy,LG,HTC,etc.
I guess it’s normally $16 but I bought on Cyber Monday so it was about $12. 12 dollars! I think if I had gone to the dealer for an after-market solution it would have been $500.
The bad first
Let’s get the bad out of the way, bearing in mind my expectations were rather low so I may be leaving out some obvious “of course it doesn’t have that…” type of stuff.
This device does an FM broadcast and you pick an unoccupied FM frequency to listen to it. On the other side it connects to a Bluetooth device such as a phone. In IT terms I’d call it a gateway since it converts one protocl to another (Bluetooth to FM). Having read the reviews, but not finding anything addressing my interests, my idea was to continue to use my FM stations, and put the station used by this device on a preset so when a call comes in to my phone I hit the station preset and accept the call on the device.
Well, you basically can’t listen to other FM stations as long as this thing is powered up. So even tuned to 88.7 at the far end of the dial, it interferes with stations up and down the dial for some reason. It’ not impossible but you’d have to have a high tolerance for static to use it that way.
Also, I’ve read that these little things break on some people after a few months. But I would no feel cheated, remember, low expectations?
The good
– microphone is good
– compatible with Samsung
– capable of audio program controls
– boots up quickly, maybe 10 seconds
My solution
I only really listen to NPR. I tried the WNYC app in the Playstore. I used to think it was buggy – stopping at random times. But I’ve had good luck my first few trips. Plays great through this thing! In many ways it’s better than FM because I don’t have to change NPR stations as I drive to work, etc, and its signal is often better. There is some static background however. Now my phone GPS talks to me through the speakers (it used to be silent in the car).
The unknown
Not sure about outbound calls to much. If you hit the button twice it seems to call the last dialed number. There are these settings U01, U02, U30. maybe those are for speed dialing?
Precisely why it has to so broadly interfere with all FM stations is a mystery.
Being a thoughtful person, I also wonder what it does to the FM reception of cars around me, ha ha? Could they pick up my call? Now that I think of it, I do remember hearing someone’s phone call on my FM radio once, many years ago. Use of an aux cord would be a way around that, but this little device does not support that.
The amazing
How cuold they pack all this tech, make something that basically works as it’s supposed to, and sell it for $12? I’m in awe.
Intro
Every now and then you find a product that is a leap ahead of where you were. Such is the case for us with regards to our product of choice for serial consoles.
The old
For Bluecoat (Symantec) proxy and AV systems, we had been using an ancient Avocent CPS device. It permitted ssh connection. It was slow and the menu very limited. But it did permit us to connect multiple serial consoles to one concentrator device at least.
For low-end firewalls we had been using DigiConnects, one per firewall. They are small, which may be thir one advantage. They are tricky to initially set up. Then they are slow to use.
In with the new
We heard about the Raritan Dominion line of products, stranegly enough, from some IT guys in Europe. It’s strange because they are right here in New Jersey – the company name probably comes form the Raritan river. But our usual reseller never heard of them. The specific device is a Dominion SXII.
It’s so much better than those older products. You can use their GUI to connect. This is a vendor who got their act together and eliminated Java. So many other security vendors have yet to do that, incredible as it is to say that.
It tries to autosense the wiring of the serial connector. That doesn’t always work, but it’s very easy for you to hardwire a port as DCE, or if that dosn’t work, try DTE. I use one type for my Symantec devices, another for firewalls.
Labelling the port with meaningful names is a snap, of course.
The Digis would interfere with the reboot process of the firewall so we’d have to detach them if we were going to rbeoot the firewall. These do not. So much better…
You can combine them with power control but we aren’t going to do that.
Don’t want to use the GUI? No problem, console access through ssh is also possible. Of configure dedicated ports that you ssh to for individual consoles.
Sending signals and cleanly disconnecting is easy with their menuss. Connecting to multiple consoles is alsono problem.
They have something called in-the-rack access. I know this will be useful but I haven’t figured out how to use it yet. But if it is what it sounds like it is, it will allow me to be in the server room and access any console by using a direct connection of some sort to the Dominion SXII.
And they’re just plain faster. A lot faster.
And, considering, they’re not so expensive.
They worked so much better than expected that we pretty much immediately filled up the ports with firewalls and other stuff.
Conclusion
A leap forward in productivity was realized by utilizing Raritn’s Dominion SXII serial port concentrator. Commissioning new security gear has never been esaier…
