Is Bluetooth useful?

I have "acquired" (translation: I have borrowed from Code Club) a couple of BBC micro:bits. These have a Bluetooth stack on them, which can be used to connect to other devices. The uBits are pretty capable microcontrollers, with lots of low power features, and if they were connected to sensors etc. they could easily transmit information to more powerful devices, like... a Raspberry Pi! Quite what I'll do with this yet I don't know, but in the best open-ended fashion, let's see if I can get anything working before we worry about an interesting application. Code Club Kids might like this...

First thing is to identify a suitable RPi. I'll be using the server, all the others are configured with the Rune image.

Next, check on the installation of BlueZ, the Linux Bluetooth stack. Need to update the distro and firmware - apt-get update, apt-get upgrade, apt-get dist-upgrade. Hurrah!

Testing... Running bluetoothctl, but it can't see any Bluetooth controllers. More research - try installing pi-bluetooth, already installed. BlueZ also already installed, but bluem not... apt running hard on this one! Still no controllers visible. Reboot....

Bingo. Controller available!

pi@server:~ $ sudo bluetoothctl

[NEW] Controller B8:27:EB:BF:C4:1D server [default]

[NEW] Device 48:74:6E:CD:96:2A John's iPhone

As can be seen, my phone is visible. Hurrah. Can't connect though. However, I'm interested as much in connecting the uBit, let's find out about that.

Super useful blog here - Martin W is a Bluetooth aficionado and has lots of info and help on Bt generally and RPi/uBit specifically.

Bluetooth Roles: (credited to Martin Woolley, at the above blog)

Bluetooth devices will play one of 4 possible Bluetooth roles as defined by that masterpiece, the Bluetooth core specification. The four roles are called

1. Peripheral
2. Central
3. Broadcaster
4. Observer

These terms are part of "GAP", the Generic Access Profile, which is a part of the Bluetooth architecture.

A Peripheral (like a uBit, smartphones with specific software) advertises, inviting and (perhaps) accepting connections from Central devices. 'Advertising' means transmitting small amounts of data, quite frequently, which other Bluetooth devices can receive and act upon if they think the advertising device is of interest.

A Central (smartphones) device scans, looking for advertising packets and based on their content, may decide to connect to a device it thinks is suitable.

A Broadcaster (Bluetooth beacon) is like a peripheral in that it advertises but it does not accept connections. It's sole purpose is to advertise.

An Observer (e.g. a beacon app on a smartphone, alerting one to special offers etc.) scans and processes advertising packets but never tries to connect to another device.

More Ripping Yarns

Background

In this post, I wrote about ripping CDs and the apparently large number of errors you get when you actually bother to check for them. I actually asked the question "Why don't programs provided on CD fail because they have so many bit errors that the code is defective?".  I discussed this with some ex-work colleagues over lunch yesterday, and we reckoned something else must be going on... A bit of research reveals that that is in fact the case!

The underlying storage mechanism is the same for CD-DA and CD-ROM (and its derivatives), but essentially, the "file system" is different.

Firstly, all CDs use the same encoding scheme - 

The Red Book specifies the physical parameters and properties of the CD, the optical "stylus" parameters, deviations and error rate, modulation system (eight-to-fourteen modulation, EFM) and error correction facility (cross-interleaved Reed–Solomon coding, CIRC), and the eight subcode channels. These parameters are common to all compact discs and used by all logical formats, such as CD-ROM. (wikipedia). 

The CIRC encoding system basically wraps lots of extra bits around the data as part of the encoding. It also scatters the logical audio frames around a number of physical frames, so that disk faults can be more easily recovered from, since they will generally degrade recoverably a number of logical frames and not obliterate the one with the error.

However, CD-ROM, as opposed to CD Digital Audio, adds in more error checksums and another layer of error correction... because it is assumed that computer data cannot be interpolated like audio data, but must be bit-perfect!!

The structures used to group data on a CD-ROM (the Yellow Book) are also derived from the Red Book. Like audio CDs (CD-DA), a CD-ROM sector contains 2,352 bytes of user data... To structure, address and protect this data, the CD-ROM standard further defines two sector modes, Mode 1 and Mode 2, which describe two different layouts for the data inside a sector.

Both Mode 1 and 2 sectors use the first 16 bytes for header information, but differ in the remaining 2,336 bytes due to the use of error correction bytes. Unlike an audio CD, a CD-ROM cannot rely on error concealment by interpolation; a higher reliability of the retrieved data is required. 

• Mode 1, used mostly for digital data, adds a 32-bit cyclic redundancy check (CRC) code for error detection, and a third layer of Reed–Solomon error correction leaving 2,048 bytes per sector available for data. 
• Mode 2, which is more appropriate for image or video data (where perfect reliability may be a little bit less important), contains no additional error detection or correction bytes, having therefore 2,336 available data bytes per sector. 

Note that both modes, like audio CDs, still benefit from the lower layers of error correction at the frame level.

Format	← 2,352 byte sector structure →
CD digital audio:	2,352 (Digital audio)
CD-ROM Mode 1:	12 (Sync pattern)	3 (Address)	1 (Mode, 0x01)	2,048 (Data)	4 (Error detection)	8 (Reserved, zero)	276 (Error correction)
CD-ROM Mode 2:	12 (Sync pattern)	3 (Address)	1 (Mode, 0x02)	2,336 (Data)

So I guess CD-DA is more liable to uncorrected errors, because nobody gives a toss about audio errors... 

Ripping programs can

• Read a sector multiple times and check they get the same result
• Use the "C2" feature implemented in many drives that allows the drive to report potential errors as guidance to the reading program

but of course, nothing can actually fix the errors if they can't be recovered, even if detected. Boo. Oh well. Off to eBay to source another CD-ROM drive...

New Ripping Software - Perfect Sound, Forever!! 

I've spent a lot of time trying to use XLD to rip my copies of Wagner's Ring to disk, and it's been very hard work. I don't know why these are so hard, but there are lots of errors, an they almost never match the AccurateRip database. So I thought I'd try dbpowerasp, the ripper produced by Spoon/Illuminate, the people who own the AccurateRip database. 

The software seems to work well in itself, it needs some adjusting in terms of tagging and filenames, but it it is taking an extraordinarily long time to rip the firstdisk. I started ripping last night, it read the first track, then announced it would retry 2000+ errors sectors. Great. I left it running when I went to bed... and when I came down this morning it was onto the 3rd track! It's 15.19, and it's still ripping the 4th, with 2676 frames to retry! The first track took 6.30 hours to rip, with its 2000 duff sectors. What is going on?! Are all my CDs going to be this hard? I reckon I should forget ripping CDs, and just play stuff off Tidal, because I can and life's too short!

Network Problems

Debugging the dodgy network... On the current running system (cheated on the systemd entry :-) ):

[root@Frontroom ~]# journalctl --output=short-iso | grep "eth0: carrier lost"

2017-02-22T18:35:43+0000 Frontroom systemd[1]: Time has been changed 

2017-02-24T04:35:42+0000 Frontroom dhcpcd[677]: eth0: carrier lost

2017-02-25T20:28:51+0000 Frontroom dhcpcd[677]: eth0: carrier lost

giving about 143,589 and 122,399 seconds between events. The lease is for 86400 seconds.

Annoyingly the Rune image clock starts on 22 Feb 2016, which is annoyingly close to the current date (25 Feb!). The --output=short-iso is required to display the year on the clock...

More data required... so I need to make the journal files non-volatile...

By default, the journal stores log data in /run/log/journal/. Since /run/ is volatile, log data is lost at reboot. To make the data persistent, it is sufficient to create /var/log/journal/ wheresystemd-journald will then store the data:

mkdir -p /var/log/journal
systemd-tmpfiles --create --prefix /var/log/journal

Tried that. Let's see if there are any more entries and if they survive a reboot!
I note that no entries have appeared in that directory yet... I wonder if I have to do something more?

Update: I edited /etc/systemd/journald.conf to change the Storage=volatile to Storage=persistent, then did systemctl restart systemd-journald.service to restart the logging with non-volatile storage. Hurrah - works!

Update:
The router log has the following entries around the time of the last outage (relevant bold):

[DHCP IP: (192.168.1.16)] to MAC address 00:BB:3A:33:62:DA, Saturday, Feb 25,2017 20:35:46
[DHCP IP: (192.168.1.3)] to MAC address B8:27:EB:25:C4:1A, Saturday, Feb 25,2017 20:28:53
[UPnP set event: Public_UPNP_C3] from source 192.168.1.11, Saturday, Feb 25,2017 20:25:28
[UPnP set event: Public_UPNP_C3] from source 192.168.1.11, Saturday, Feb 25,2017 20:10:27
[Time synchronized with NTP server] Saturday, Feb 25,2017 20:09:33
[Internet connected] IP address: 192.168.0.3, Saturday, Feb 25,2017 20:08:45
[UPnP set event: Public_UPNP_C3] from source 192.168.1.11, Saturday, Feb 25,2017 19:55:28
[UPnP set event: Public_UPNP_C3] from source 192.168.1.11, Saturday, Feb 25,2017 19:40:27
[Time synchronized with NTP server] Saturday, Feb 25,2017 19:38:43

That doesn't tell me a lot, but at least they agree! And there is no apparent fault with the router. I do note that my phone gets a lot of IP address assignments, at sub-10 minute intervals, which I notice. Maybe the signal is bad for that?

As an experiment, I might try plugging in the network extender I have and using that to provide a wired interface, to see if that makes a difference. The office RPi is using one of those and has no wired problem, although the wireless connection does fail a lot, despite using the wireless extender in the same room!!!

Update 2017-02-28:

Well, the link has been up now for 64 hours, without failing, using the Powerline network extender and a new, short Cat5 cable. This is positive. Maybe it's like my N years spent complaining about the laser printer's inadequacy and the uselessness of the drivers, when it was the cable all along...

Rune vs. Roon?

Up until now I've used Rune as the audio player on my Raspberry Pis. It's a cut-down ArchLinux using mpd as the player and a PHP-based web interface and control server to manage and configure the mpd and o/s.

It works ok most of the time. However, and maybe this is not a problem specific to Rune, it is fairly flakey in respect of network connectedness. Yeah, on startup it usually connects and exposes itself as host.local, connects to the server for ripped data, is ready to receive DLNA/uPnP streams and reports to interested parties like Linn Kazoo and Lumin on iOS.

It's hard to work out what's going on, because the problem is network connectivity, so beaming in on SSH is not possible, and a restart appears to kill the log files - I need to research this a bit more. The log shows outage of the wired connection, which is weird... These entries show it's down for around 1 second! What's going on?

Feb 25 20:28:51 Frontroom kernel: smsc95xx 1-1.1:1.0 eth0: link down

Feb 25 20:28:51 Frontroom dhcpcd[677]: eth0: carrier lost

Feb 25 20:28:51 Frontroom dhcpcd[677]: eth0: deleting route to 192.168.1.0/24

Feb 25 20:28:51 Frontroom dhcpcd[677]: eth0: deleting default route via 192.168.1.1

Feb 25 20:28:51 Frontroom avahi-daemon[275]: Withdrawing address record for 192.168.1.3 on eth0.

Feb 25 20:28:51 Frontroom avahi-daemon[275]: Leaving mDNS multicast group on interface eth0.IPv4 with address 192.168.1.3.

Feb 25 20:28:51 Frontroom avahi-daemon[275]: Interface eth0.IPv4 no longer relevant for mDNS.

Feb 25 20:28:52 Frontroom ifplugd[280]: Link beat lost.

Feb 25 20:28:52 Frontroom dhcpcd[677]: eth0: carrier acquired

Feb 25 20:28:52 Frontroom kernel: smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0x45E1

Feb 25 20:28:52 Frontroom dhcpcd[677]: eth0: IAID eb:25:c4:1a

Feb 25 20:28:53 Frontroom dhcpcd[677]: eth0: rebinding lease of 192.168.1.3

Feb 25 20:28:53 Frontroom dhcpcd[677]: eth0: probing address 192.168.1.3/24

Feb 25 20:28:53 Frontroom ifplugd[280]: Link beat detected.

Feb 25 20:28:54 Frontroom ntpd[348]: Deleting interface #5 eth0, 192.168.1.3#123, interface stats: received=73, sent=75, dropped

Feb 25 20:28:54 Frontroom ntpd[348]: 178.79.160.57 local addr 192.168.1.3 -> <null>

Feb 25 20:28:57 Frontroom dhcpcd[677]: eth0: leased 192.168.1.3 for 86400 seconds

Feb 25 20:28:57 Frontroom avahi-daemon[275]: Joining mDNS multicast group on interface eth0.IPv4 with address 192.168.1.3.

Feb 25 20:28:57 Frontroom avahi-daemon[275]: New relevant interface eth0.IPv4 for mDNS.

Feb 25 20:28:57 Frontroom avahi-daemon[275]: Registering new address record for 192.168.1.3 on eth0.IPv4.

Feb 25 20:28:57 Frontroom dhcpcd[677]: eth0: adding route to 192.168.1.0/24

Feb 25 20:28:57 Frontroom dhcpcd[677]: eth0: adding default route via 192.168.1.1

Feb 25 20:28:57 Frontroom dhcpcd[677]: eth0: removing route to 192.168.1.0/24

Feb 25 20:28:59 Frontroom ntpd[348]: Listen normally on 6 eth0 192.168.1.3:123

Feb 25 20:28:59 Frontroom ntpd[348]: 178.79.160.57 local addr 192.168.1.12 -> 192.168.1.3

Feb 25 20:28:59 Frontroom ntpd[348]: new interface(s) found: waking up resolver

Anyway, I've been investigating Roon, which I first encountered at Keith's house when I heard the Kii Audio Threes. He's running a MacMini as the Roon Core, the Rune Control on an iPad and using the Mac Mini as a Roon Output. it all seems very well thought through, and pretty robust. The one drawback is that it costs money, continuing money, at $120/year or $500 lifetime! It does have a fantastic interface, some amazing metadata capabilities and it also interfaces utterly seamlessly with Tidal. I'd have to provide a sensibly powerful box for the Core, I suspect an RPi isn't going to cut it, in fact, the Roon doco explicitly says it won't. 

But all this is moot if my hub is letting me down - how do I debug the network interface??

A Video Sidetrack

I have a spare USB cam, a new RPi 3 B and a boiler in the loft that I want to monitor the front panel of without constantly going upstairs, climbing the ladder and hoiking myself into the roof. Clearly a webcam is the answer!

I tried using ssh & X to connect remotely and view the camera in real-time, but it seems to have problems of one sort or another. The whole thing works fine when using the HDMI output, but not so well over X. I tried using cheese, but that doesn't work over X (bug!) and VLC - that struggles too, it can't find any useful OpenGL renderers for X. So I'm about to try UV4L from http://www.linux-projects.org/uv4l/installation/, which appears to offer live streaming options. Hurray!

Using .local DNS names

Up until now,  the Rune installations (based on ArchLinux) haven't been able to use the Bonjour .local domain to do lookups. They broadcast their own hostnames, so they can be seen from other places, but they can't see each other or the server. Boring.

How do you fix this?? Answer here...

Install nss-mdns:

pacman -S nss-mdns

Tell C libs to use mDNS:

vi /etc/nsswitch.conf

Add the value mdns_minimal [NOTFOUND=return] in the hosts line...

Then it works!

I think I should tell Frank on the Rune forum about this...

Rune Audio, RPi and networking recovery

It seems that if the wireless/wired router is rebooted, then all the Rune Audio instances have to be restarted to link up with the wired interface (and possibly the wireless). If this is true, this is very boring. It certainly seems to be true - I have to reboot the router sometimes because it gets upset and won't connect my phone (1st world problems eh??).

So I'm looking at the networking setup in Rune - here's the Rune debug first few lines:

###### System info ######
Linux version 4.1.20-1-ARCH (builduser@leming) (gcc version 5.3.0 (GCC) ) #1 SMP Sat Mar 19 20:07:23 MDT 2016

system time: Tue Nov 22 15:54:10 GMT 2016

system load: 0.19 0.10 0.06 1/181 3960

HW platform: RaspberryPi2 (08)

playerID: 08b26fff2ac4ddac6fee7fbbc1890504ae

I'm using the Office system, because that's the one I have configured with

• A wired connection through an Airport Express, so it's actually wireless but looks like a wired connection to the RPi
• A wireless connection to the Netgear router

You can see these here:

[root@office ~]# ifconfig

eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500

        inet 192.168.1.12  netmask 255.255.255.0  broadcast 192.168.1.255

        ether b8:27:eb:d3:a9:ca  txqueuelen 1000  (Ethernet)

        RX packets 747196  bytes 156859854 (149.5 MiB)

        RX errors 0  dropped 8  overruns 0  frame 0

        TX packets 573333  bytes 203126147 (193.7 MiB)

        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

wlan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500

        inet 192.168.1.14  netmask 255.255.255.0  broadcast 192.168.1.255

        ether b8:27:eb:86:fc:9f  txqueuelen 1000  (Ethernet)

        RX packets 31182  bytes 3441166 (3.2 MiB)

        RX errors 0  dropped 3566  overruns 0  frame 0

        TX packets 2181  bytes 412069 (402.4 KiB)

        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

I can't see them properly in the router - it appears to be a bit confused (maybe it's the fricking router that's the problem...) - here's the devices connected

Wired Devices

#	IP Address	Device Name	MAC Address
1	192.168.1.3	server	B8:27:EB:15:6E:B7
2	192.168.1.4	Frontroom	B8:27:EB:25:C4:1A
3	192.168.1.11	FRONTROOM	B8:27:EB:25:C4:1A

 Wireless Devices (Wireless intruders also show up here)

#	IP Address	Device Name	MAC Address
1	192.168.1.12	office	B8:27:EB:D3:A9:CA
2	192.168.1.2	johns-airport-express	00:1F:F3:07:9F:EB
3	--	--	B8:27:EB:86:FC:9F
4	192.168.1.13	meye-55ace5a8	00:0F:60:06:7E:10
5	--	--	B8:27:EB:70:91:4F
6	192.168.1.10	meye-e5167b33	74:DA:38:3A:33:7C
7	192.168.1.7	Macintosh-Gouk	D8:A2:5E:97:E7:E6
8	192.168.1.6	Jenny-PC	1C:65:9D:48:E0:77
9	--	--	F0:DB:F8:69:8E:97

Obviously, 192.168.1.12 is the wired connection (eth0), it shows up here because it's via the Airport Express (192.168.1.2). The wireless connection (wlan0) is actually at 192.168.1.14, on B8:27:EB:86:FC:9F - I know because I can telnet into it!! Weird. The router is shyte, really!!

Anyway, I have been testing the unplug/replug of the wired connection, and the unplug/replug of the Airport Express, thereby simulating the two different situations with the usual router. It's hard to do this for real because if I unplug the router I lose connectivity to the RPi. I guess I could look at the logs after the fact, if they survive a reboot, I think they do.

Commands Used

Rune uses ArchLinux. The commands I'm using to investigate the networking activity are:

• journalctl - enables listing of the system journal. Use -f to tail the journal
• message <your message> - sends a message to the system journal, very handy for documenting equipment state changes in the log alongside the system's reaction to them
• systemctl - useful for listing the running services etc.

Results

Interesting! The first time I did it, the eth0 interface didn't seem to reconnect (highlighted time a result of search hit on "15:40"!); irrelevant entries deleted:

Cable unplugged

Nov 22 15:40:08 office dhcpcd[1057]: eth0: carrier lost

Nov 22 15:40:08 office kernel: smsc95xx 1-1.1:1.0 eth0: link down

Nov 22 15:40:09 office dhcpcd[1057]: eth0: deleting route to 192.168.1.0/24

Nov 22 15:40:09 office dhcpcd[1057]: eth0: deleting default route via 192.168.1.1

Nov 22 15:40:09 office ifplugd[224]: Link beat lost.

Nov 22 15:40:15 office ifplugd[224]: Executing '/etc/ifplugd/netctl.action eth0 down'.

Nov 22 15:40:15 office ifplugd[224]: client: Stopping network profile 'eth0'...

Nov 22 15:40:15 office dhcpcd[474]: sending signal TERM to pid 1057

Nov 22 15:40:15 office dhcpcd[474]: waiting for pid 1057 to exit

Nov 22 15:40:15 office dhcpcd[1057]: received SIGTERM, stopping

Nov 22 15:40:15 office dhcpcd[1057]: eth0: removing interface

Nov 22 15:40:15 office dhcpcd[1057]: dhcpcd exited

Nov 22 15:40:15 office ifplugd[224]: client: Stopped network profile 'eth0'

Nov 22 15:40:15 office kernel: smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup

Nov 22 15:40:15 office ifplugd[224]: Program executed successfully.

Nov 22 15:40:15 office kernel: smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup

Cable replugged

Nov 22 15:40:25 office kernel: smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0x45E1

Nov 22 15:40:25 office ifplugd[224]: Link beat detected.

Nov 22 15:40:26 office ifplugd[224]: Executing '/etc/ifplugd/netctl.action eth0 up'.

Nov 22 15:40:26 office ifplugd[224]: client: Starting network profile 'eth0'...

Nov 22 15:40:26 office dhcpcd[511]: DUID 00:01:00:01:1c:72:2b:ea:06:92:c5:a0:0d:d6

Nov 22 15:40:26 office dhcpcd[511]: eth0: IAID eb:d3:a9:ca

Nov 22 15:40:26 office dhcpcd[511]: eth0: rebinding lease of 192.168.1.12

Nov 22 15:40:31 office dhcpcd[511]: eth0: NAK: from 192.168.1.1

Nov 22 15:40:31 office dhcpcd[511]: eth0: soliciting a DHCP lease

Nov 22 15:40:32 office dhcpcd[511]: eth0: offered 192.168.1.12 from 192.168.1.1

Nov 22 15:40:32 office dhcpcd[511]: eth0: probing address 192.168.1.12/24

Nov 22 15:40:37 office dhcpcd[511]: eth0: leased 192.168.1.12 for 86400 seconds

Nov 22 15:40:37 office dhcpcd[511]: eth0: adding route to 192.168.1.0/24

Nov 22 15:40:37 office dhcpcd[511]: eth0: adding default route via 192.168.1.1

Nov 22 15:40:37 office dhcpcd[511]: forked to background, child pid 582

Nov 22 15:40:37 office ifplugd[224]: client: Started network profile 'eth0'

Nov 22 15:40:37 office ifplugd[224]: Program executed successfully.

Router unplugged

Nov 22 15:41:03 office dhcpcd[582]: eth0: carrier lost

Nov 22 15:41:03 office kernel: smsc95xx 1-1.1:1.0 eth0: link down

Nov 22 15:41:03 office ifplugd[224]: Link beat lost.

Nov 22 15:41:03 office dhcpcd[582]: eth0: deleting route to 192.168.1.0/24

Nov 22 15:41:03 office dhcpcd[582]: eth0: deleting default route via 192.168.1.1

Nov 22 15:41:09 office ifplugd[224]: Executing '/etc/ifplugd/netctl.action eth0 down'.

Nov 22 15:41:09 office ifplugd[224]: client: Stopping network profile 'eth0'...

Nov 22 15:41:09 office dhcpcd[653]: sending signal TERM to pid 582

Nov 22 15:41:09 office dhcpcd[653]: waiting for pid 582 to exit

Nov 22 15:41:09 office dhcpcd[582]: received SIGTERM, stopping

Nov 22 15:41:09 office dhcpcd[582]: eth0: removing interface

Nov 22 15:41:09 office dhcpcd[582]: dhcpcd exited

Nov 22 15:41:09 office kernel: smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup

Nov 22 15:41:09 office ifplugd[224]: client: Stopped network profile 'eth0'

Nov 22 15:41:10 office ifplugd[224]: Program executed successfully.

Nov 22 15:41:10 office kernel: smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup

Nov 22 15:42:03 office kernel: smsc95xx 1-1.1:1.0 eth0: link up, 10Mbps, half-duplex, lpa 0x0020

Router replugged

Nov 22 15:42:04 office ifplugd[224]: Link beat detected.

Nov 22 15:42:05 office ifplugd[224]: Executing '/etc/ifplugd/netctl.action eth0 up'.

Nov 22 15:42:05 office ifplugd[224]: client: Starting network profile 'eth0'...

Nov 22 15:42:05 office dhcpcd[707]: DUID 00:01:00:01:1c:72:2b:ea:06:92:c5:a0:0d:d6

Nov 22 15:42:05 office dhcpcd[707]: eth0: IAID eb:d3:a9:ca

Nov 22 15:42:05 office dhcpcd[707]: eth0: rebinding lease of 192.168.1.12

Nov 22 15:42:10 office dhcpcd[707]: eth0: DHCP lease expired

Nov 22 15:42:10 office dhcpcd[707]: eth0: soliciting a DHCP lease

Nov 22 15:42:18 office dhcpcd[707]: eth0: carrier lost

Nov 22 15:42:18 office kernel: smsc95xx 1-1.1:1.0 eth0: link down

Nov 22 15:42:20 office dhcpcd[707]: eth0: carrier acquired

Nov 22 15:42:20 office kernel: smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0x45E1

Nov 22 15:42:21 office dhcpcd[707]: eth0: IAID eb:d3:a9:ca

Nov 22 15:42:21 office dhcpcd[707]: eth0: soliciting a DHCP lease

Nov 22 15:42:35 office dhcpcd[707]: timed out

Nov 22 15:42:35 office dhcpcd[707]: dhcpcd exited

Nov 22 15:42:35 office ifplugd[224]: client: <3>DHCP IPv4 lease attempt failed on interface 'eth0'

Nov 22 15:42:35 office ifplugd[224]: client: <3>Failed to bring the network up for profile 'eth0'

Nov 22 15:42:35 office ifplugd[224]: client: <3>Could not start any suitable profile

Nov 22 15:42:35 office ifplugd[224]: Program execution failed, return value is 1.

Nov 22 15:42:35 office kernel: smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup

Nov 22 15:42:35 office ifplugd[224]: Link beat lost.

Nov 22 15:42:35 office kernel: smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup

Nov 22 15:42:37 office kernel: smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0x45E1

Nov 22 15:42:37 office ifplugd[224]: Link beat detected.

At this point, ifconfig was not showing any IP address associated with eth0, although it was shown as "running"... So I invoked netctl stop/start eth0... Maybe I should have waited longer?

Nov 22 15:45:59 office systemd[1]: Stopped Networking for netctl profile eth0.

Nov 22 15:46:08 office systemd[1]: Created slice system-netctl.slice.

Nov 22 15:46:08 office systemd[1]: Starting Networking for netctl profile eth0...

Nov 22 15:46:08 office network[917]: Starting network profile 'eth0'...

Nov 22 15:46:08 office dhcpcd[922]: DUID 00:01:00:01:1c:72:2b:ea:06:92:c5:a0:0d:d6

Nov 22 15:46:08 office dhcpcd[922]: eth0: IAID eb:d3:a9:ca

Nov 22 15:46:09 office dhcpcd[922]: eth0: soliciting a DHCP lease

Nov 22 15:46:14 office dhcpcd[922]: eth0: offered 192.168.1.12 from 192.168.1.1

Nov 22 15:46:14 office dhcpcd[922]: eth0: probing address 192.168.1.12/24

Nov 22 15:46:18 office dhcpcd[922]: eth0: leased 192.168.1.12 for 86400 seconds

Nov 22 15:46:18 office dhcpcd[922]: eth0: adding route to 192.168.1.0/24

Nov 22 15:46:18 office dhcpcd[922]: eth0: adding default route via 192.168.1.1

Nov 22 15:46:19 office dhcpcd[922]: forked to background, child pid 969

Nov 22 15:46:19 office network[917]: Started network profile 'eth0'

Nov 22 15:46:19 office systemd[1]: Started Networking for netctl profile eth0.

And after that it was running ok. But I had intervened...

So time for a better documented test. I switched wlan0 to the normal router (192.1.68.1.xxx) first, otherwise I couldn't talk to it properly.

Nov 22 16:02:05 office root[4543]: +++++++ Cable unplugged

Nov 22 16:02:31 office dhcpcd[969]: eth0: carrier lost

Nov 22 16:02:31 office kernel: smsc95xx 1-1.1:1.0 eth0: link down

Nov 22 16:02:31 office dhcpcd[969]: eth0: deleting route to 192.168.1.0/24

Nov 22 16:02:31 office dhcpcd[969]: eth0: deleting default route via 192.168.1.1

Nov 22 16:02:32 office ifplugd[224]: Link beat lost.

Nov 22 16:02:33 office ntpd[284]: Deleting interface #6 eth0, 192.168.1.12#123, interface stats: received=9, sent=10, dropped=0, active_time=973 secs

Nov 22 16:02:38 office ifplugd[224]: Executing '/etc/ifplugd/netctl.action eth0 down'.

Nov 22 16:02:38 office ifplugd[224]: Program execution failed, return value is 1.

Nov 22 16:02:59 office root[4612]: +++++++ Cable replugged

Nov 22 16:03:04 office dhcpcd[969]: eth0: carrier acquired

Nov 22 16:03:04 office kernel: smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0x45E1

Nov 22 16:03:04 office dhcpcd[969]: eth0: IAID eb:d3:a9:ca

Nov 22 16:03:04 office ifplugd[224]: Link beat detected.

Nov 22 16:03:04 office dhcpcd[969]: eth0: rebinding lease of 192.168.1.12

Nov 22 16:03:05 office ifplugd[224]: Executing '/etc/ifplugd/netctl.action eth0 up'.

Nov 22 16:03:05 office ifplugd[224]: client: Starting network profile 'eth0'...

Nov 22 16:03:05 office dhcpcd[4633]: dhcpcd already running on pid 969 (/run/dhcpcd-eth0-4.pid)

Nov 22 16:03:05 office ifplugd[224]: client: <3>DHCP IPv4 lease attempt failed on interface 'eth0'

Nov 22 16:03:05 office dhcpcd[969]: eth0: carrier lost

Nov 22 16:03:05 office kernel: smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup

Nov 22 16:03:05 office ifplugd[224]: client: <3>Failed to bring the network up for profile 'eth0'

Nov 22 16:03:05 office ifplugd[224]: client: <3>Could not start any suitable profile

Nov 22 16:03:05 office ifplugd[224]: Program execution failed, return value is 1.

Nov 22 16:03:05 office ifplugd[224]: Link beat lost.

Nov 22 16:03:05 office kernel: smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup

Nov 22 16:03:05 office dhcpcd[969]: eth0: carrier acquired

Nov 22 16:03:05 office dhcpcd[969]: eth0: IAID eb:d3:a9:ca

Nov 22 16:03:05 office dhcpcd[969]: eth0: rebinding lease of 192.168.1.12

Nov 22 16:03:07 office kernel: smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0x45E1

Nov 22 16:03:07 office ifplugd[224]: Link beat detected.

Nov 22 16:03:10 office dhcpcd[969]: eth0: DHCP lease expired

Nov 22 16:03:10 office dhcpcd[969]: eth0: soliciting a DHCP lease

Nov 22 16:03:15 office dhcpcd[969]: eth0: offered 192.168.1.12 from 192.168.1.1

Nov 22 16:03:15 office dhcpcd[969]: eth0: probing address 192.168.1.12/24

Nov 22 16:03:19 office dhcpcd[969]: eth0: leased 192.168.1.12 for 86400 seconds

Nov 22 16:03:19 office dhcpcd[969]: eth0: adding route to 192.168.1.0/24

Nov 22 16:03:19 office dhcpcd[969]: eth0: adding default route via 192.168.1.1

Nov 22 16:03:19 office dhcpcd[969]: eth0: removing route to 192.168.1.0/24

Looks like the cable un/replug works like last time... Try the router

Nov 22 16:06:05 office root[4784]: +++++++ Router unplugged

Nov 22 16:06:11 office dhcpcd[969]: eth0: carrier lost

Nov 22 16:06:11 office kernel: smsc95xx 1-1.1:1.0 eth0: link down

Nov 22 16:06:11 office dhcpcd[969]: eth0: deleting default route via 192.168.1.1

Nov 22 16:06:11 office avahi-daemon[221]: Withdrawing address record for 192.168.1.12 on eth0.

Nov 22 16:06:11 office avahi-daemon[221]: Leaving mDNS multicast group on interface eth0.IPv4 with address 192.168.1.12.

Nov 22 16:06:11 office avahi-daemon[221]: Interface eth0.IPv4 no longer relevant for mDNS.

Nov 22 16:06:11 office ifplugd[224]: Link beat lost.

Nov 22 16:06:13 office ntpd[284]: Deleting interface #9 eth0, 192.168.1.12#123, interface stats: received=0, sent=0, dropped=0, active_time=172 secs

Nov 22 16:06:17 office ifplugd[224]: Executing '/etc/ifplugd/netctl.action eth0 down'.

Nov 22 16:06:17 office ifplugd[224]: Program execution failed, return value is 1.

Nov 22 16:07:25 office root[4866]: +++++++ Router replugged

Nov 22 16:08:08 office dhcpcd[969]: eth0: carrier acquired

Nov 22 16:08:08 office kernel: smsc95xx 1-1.1:1.0 eth0: link up, 10Mbps, half-duplex, lpa 0x0020

Nov 22 16:08:09 office ifplugd[224]: Link beat detected.

Nov 22 16:08:09 office dhcpcd[969]: eth0: IAID eb:d3:a9:ca

Nov 22 16:08:09 office dhcpcd[969]: eth0: rebinding lease of 192.168.1.12

Nov 22 16:08:10 office ifplugd[224]: Executing '/etc/ifplugd/netctl.action eth0 up'.

Nov 22 16:08:10 office ifplugd[224]: client: Starting network profile 'eth0'...

Nov 22 16:08:10 office dhcpcd[4911]: dhcpcd already running on pid 969 (/run/dhcpcd-eth0-4.pid)

Nov 22 16:08:10 office ifplugd[224]: client: <3>DHCP IPv4 lease attempt failed on interface 'eth0'

Nov 22 16:08:10 office dhcpcd[969]: eth0: carrier lost

Nov 22 16:08:10 office ifplugd[224]: client: <3>Failed to bring the network up for profile 'eth0'

Nov 22 16:08:10 office ifplugd[224]: client: <3>Could not start any suitable profile

Nov 22 16:08:10 office ifplugd[224]: Program execution failed, return value is 1.

Nov 22 16:08:10 office kernel: smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup

Nov 22 16:08:10 office ifplugd[224]: Link beat lost.

Nov 22 16:08:10 office kernel: smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup

Nov 22 16:08:10 office dhcpcd[969]: eth0: carrier acquired

Nov 22 16:08:10 office dhcpcd[969]: eth0: IAID eb:d3:a9:ca

Nov 22 16:08:10 office dhcpcd[969]: eth0: rebinding lease of 192.168.1.12

Nov 22 16:08:12 office kernel: smsc95xx 1-1.1:1.0 eth0: link up, 10Mbps, half-duplex, lpa 0x0020

Nov 22 16:08:13 office ifplugd[224]: Link beat detected.

Nov 22 16:08:15 office dhcpcd[969]: eth0: DHCP lease expired

Nov 22 16:08:15 office dhcpcd[969]: eth0: soliciting a DHCP lease

Nov 22 16:08:23 office dhcpcd[969]: eth0: carrier lost

Nov 22 16:08:23 office kernel: smsc95xx 1-1.1:1.0 eth0: link down

Nov 22 16:08:24 office ifplugd[224]: Link beat lost.

Nov 22 16:08:26 office dhcpcd[969]: eth0: carrier acquired

Nov 22 16:08:26 office kernel: smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lap 0x45E1
Nov 22 16:08:26 office dhcpcd[969]: eth0: IAID eb:d3:a9:ca

Nov 22 16:08:26 office dhcpcd[969]: eth0: soliciting a DHCP lease

Nov 22 16:08:27 office ifplugd[224]: Link beat detected.

Nov 22 16:08:54 office dhcpcd[969]: eth0: offered 192.168.1.12 from 192.168.1.1

Nov 22 16:08:54 office dhcpcd[969]: eth0: probing address 192.168.1.12/24

Nov 22 16:08:59 office dhcpcd[969]: eth0: leased 192.168.1.12 for 86400 seconds

Nov 22 16:08:59 office dhcpcd[969]: eth0: adding route to 192.168.1.0/24

Nov 22 16:08:59 office dhcpcd[969]: eth0: adding default route via 192.168.1.1

Nov 22 16:08:59 office dhcpcd[969]: eth0: removing route to 192.168.1.0/24

Nov 22 16:13:41 office root[5157]: +++++++ Router unplugged

Nov 22 16:13:48 office dhcpcd[969]: eth0: carrier lost

Nov 22 16:13:48 office kernel: smsc95xx 1-1.1:1.0 eth0: link down

Nov 22 16:13:48 office dhcpcd[969]: eth0: deleting default route via 192.168.1.1

Nov 22 16:13:48 office ifplugd[224]: Link beat lost.

Nov 22 16:13:54 office ifplugd[224]: Executing '/etc/ifplugd/netctl.action eth0 down'.

Nov 22 16:13:54 office ifplugd[224]: Program execution failed, return value is 1.

Nov 22 16:14:30 office root[5224]: +++++++ Router replugged

Nov 22 16:15:16 office dhcpcd[969]: eth0: carrier acquired

Nov 22 16:15:16 office ifplugd[224]: Link beat detected.

Nov 22 16:15:16 office kernel: smsc95xx 1-1.1:1.0 eth0: link up, 10Mbps, half-duplex, lpa 0x0020

Nov 22 16:15:16 office dhcpcd[969]: eth0: IAID eb:d3:a9:ca

Nov 22 16:15:17 office dhcpcd[969]: eth0: rebinding lease of 192.168.1.12

Nov 22 16:15:17 office ifplugd[224]: Executing '/etc/ifplugd/netctl.action eth0 up'.

Nov 22 16:15:17 office ifplugd[224]: client: Starting network profile 'eth0'...

Nov 22 16:15:17 office dhcpcd[5261]: dhcpcd already running on pid 969 (/run/dhcpcd-eth0-4.pid)

Nov 22 16:15:17 office ifplugd[224]: client: <3>DHCP IPv4 lease attempt failed on interface 'eth0'

Nov 22 16:15:17 office dhcpcd[969]: eth0: carrier lost

Nov 22 16:15:17 office ifplugd[224]: client: <3>Failed to bring the network up for profile 'eth0'

Nov 22 16:15:17 office kernel: smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup

Nov 22 16:15:17 office ifplugd[224]: client: <3>Could not start any suitable profile

Nov 22 16:15:17 office ifplugd[224]: Program execution failed, return value is 1.

Nov 22 16:15:18 office ifplugd[224]: Link beat lost.

Nov 22 16:15:18 office kernel: smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup

Nov 22 16:15:18 office dhcpcd[969]: eth0: carrier acquired

Nov 22 16:15:18 office dhcpcd[969]: eth0: IAID eb:d3:a9:ca

Nov 22 16:15:18 office dhcpcd[969]: eth0: rebinding lease of 192.168.1.12

Nov 22 16:15:20 office kernel: smsc95xx 1-1.1:1.0 eth0: link up, 10Mbps, half-duplex, lap 0x0020

Nov 22 16:15:21 office ifplugd[224]: Link beat detected.Nov 22 16:15:23 office dhcpcd[969]: eth0: DHCP lease expired

Nov 22 16:15:23 office dhcpcd[969]: eth0: soliciting a DHCP lease

Nov 22 16:15:31 office dhcpcd[969]: eth0: carrier lost

Nov 22 16:15:31 office kernel: smsc95xx 1-1.1:1.0 eth0: link down

Nov 22 16:15:32 office ifplugd[224]: Link beat lost.

Nov 22 16:15:34 office dhcpcd[969]: eth0: carrier acquired

Nov 22 16:15:34 office kernel: smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0x45E1

Nov 22 16:15:34 office dhcpcd[969]: eth0: IAID eb:d3:a9:ca

Nov 22 16:15:34 office dhcpcd[969]: eth0: soliciting a DHCP lease

Nov 22 16:15:35 office ifplugd[224]: Link beat detected.

Nov 22 16:15:46 office dhcpcd[969]: eth0: offered 192.168.1.12 from 192.168.1.1

Nov 22 16:15:46 office dhcpcd[969]: eth0: probing address 192.168.1.12/24

Nov 22 16:15:51 office dhcpcd[969]: eth0: leased 192.168.1.12 for 86400 seconds

Nov 22 16:15:51 office dhcpcd[969]: eth0: adding route to 192.168.1.0/24

Nov 22 16:15:51 office dhcpcd[969]: eth0: adding default route via 192.168.1.1

Nov 22 16:15:51 office dhcpcd[969]: eth0: removing route to 192.168.1.0/24

Hmm. The main difference between the initial (failed) attempt and the (successful) subsequent attempts is that in the latter case the ifplugd daemon fails to stop the related dhcpcd instance, so it presumably keeps going and then eventually acquires an IP address. So why doesn't that work in the former case?? Aha...

Nov 22 15:42:35 office dhcpcd[707]: timed out

That's what happens - at that point, the dhcpcd stops, and is not restarted. I wonder if I can tweak the timeout??

Let's see what systemctl says...

[root@office etc]# systemctl status netctl@eth0.service

● netctl@eth0.service - Networking for netctl profile eth0

   Loaded: loaded (/usr/lib/systemd/system/netctl@.service; static; vendor preset: disabled)

   Active: active (exited) since Tue 2016-11-22 15:46:19 GMT; 4h 2min ago

     Docs: man:netctl.profile(5)

 Main PID: 917 (code=exited, status=0/SUCCESS)

   CGroup: /system.slice/system-netctl.slice/netctl@eth0.service

           └─969 dhcpcd -4 -q -t 30 -L eth0

Nov 22 16:15:31 office dhcpcd[969]: eth0: carrier lost

Nov 22 16:15:34 office dhcpcd[969]: eth0: carrier acquired

Nov 22 16:15:34 office dhcpcd[969]: eth0: IAID eb:d3:a9:ca

Nov 22 16:15:34 office dhcpcd[969]: eth0: soliciting a DHCP lease

Nov 22 16:15:46 office dhcpcd[969]: eth0: offered 192.168.1.12 from 192.168.1.1

Nov 22 16:15:46 office dhcpcd[969]: eth0: probing address 192.168.1.12/24

Nov 22 16:15:51 office dhcpcd[969]: eth0: leased 192.168.1.12 for 86400 seconds

Nov 22 16:15:51 office dhcpcd[969]: eth0: adding route to 192.168.1.0/24

Nov 22 16:15:51 office dhcpcd[969]: eth0: adding default route via 192.168.1.1

Nov 22 16:15:51 office dhcpcd[969]: eth0: removing route to 192.168.1.0/24

Looks like it gets started here:

Feb 22 14:40:20 office ifplugd[224]: Executing '/etc/ifplugd/netctl.action eth0 up'.

Feb 22 14:40:20 office ifplugd[224]: client: Starting network profile 'eth0'...

Feb 22 14:40:20 office dhcpcd[383]: DUID 00:01:00:01:1c:72:2b:ea:06:92:c5:a0:0d:d6

Feb 22 14:40:20 office dhcpcd[383]: eth0: IAID eb:d3:a9:ca

ArchLinux uses systemd, not init!!

/etc/ifplugd/netctl.action ->

    $1 = etho
    $2 = up

  . /usr/lib/network/globals

    {PROFILE_DIR="/etc/netctl"

    {SUBR_DIR="/usr/lib/network"

    {STATE_DIR="/run/network"

    {STATE_FILE="${NETCTL_STATE_FILE:-/var/lib/netctl/netctl.state}"

    PROFILE_FILE="/run/network/ifplugd_eth0.profile"

  case "up" in

    up)

      while read -r profile; do

          if ForceConnect=yes "/usr/lib/network/network" start "eth0"; then

              mkdir -p "$(dirname "/run/network/ifplugd_eth0.profile")"

              printf "%s" "$profile" > "/run/network/ifplugd_eth0.profile"

              exit 0

          fi

      done < <(list_profiles | while read -r profile; do

          report_debug "Examining profile 'eth0'"

          (

            source "/etc/netctl/eth0" > /dev/null

which has 

    Description='eth0 connection'

    Interface=eth0

    ForceConnect=yes

    SkipNoCarrier=yes

    Connection=ethernet

    IP=dhcp

So - no obvious clues there... let's look at the referenced SUBR file /usr/lib/network/network:

$1 = start
$2 = eth0

# Expose the profile name

Profile=eth0

load_profile "$Profile"

which translates to

## Sources all hooks, a profile and any interface hook

# $1: profile name

load_profile() {

    local hook

    if [[ ! -r "/etc/netctl/etho" ]]; then

        exit_error "Profile 'eth0' does not exist or is not readable"

    fi
...

    source "/etc/netctl/$1"

    if [[ -z eth0 ]]; then

        exit_error "Profile 'eth0' does not specify an interface"

    fi

    if [[ ! -r "${ethernet:+/usr/lib/network/connections/ethernet}" ]]; then

        exit_error "Profile 'eth0' does not specify a valid connection"

    fi

    if [[ -x "$PROFILE_DIR/interfaces/eth0" ]]; then

        source "$PROFILE_DIR/interfaces/eth0"

    fi

    source "/usr/lib/network/connections/ethernet"

which contains

. "/usr/lib/network/ip" - contains some DHCP-invoking code!!

which we want to end up with a result like
dhcpcd -4 -q -t 30 -L eth0

dhcp_call "${DHCPClient:-dhcpcd}" start 4

## Interface a DHCP client

# $1: DHCP client - dhcpcd

# $2: command     - start

# $3...: additional arguments - 4

dhcp_call() {

    local client="dhcpcd" command="start"

    shift 2

    if [[ ! -r "/usr/lib/network/dhcp/dhcpcd" ]]; then

        report_error "DHCP client 'dhcpcd' is unsupported"

        return 127

    fi

    if ! source "/usr/lib/network/dhcp/dhcpcd"; then

        report_error "DHCP client 'dhcpcd' is not installed or not ready"

        return 127

    fi

    "dhcpcd_start" "4"

}

The file /usr/lib/network/dhcp/dhcpcd contains:

dhcpcd_start() {

    local options

    case $1 in

      4) options="$DhcpcdOptions -L";; - guess we're going for IP4!

      6) options=$DhcpcdOptions6;;

      *) return 1;;

    esac

    if [[ $2 == "noaddr" ]]; then

        report_error "Using 'dhcpcd' for configuration without address assignment is unsupported"

        return 1

    fi

    # If using own dns, tell dhcpcd to NOT replace resolv.conf

    [[ $DNS ]] && options+=" -C resolv.conf"

    if ! do_debug do_readable dhcpcd -$1 -q -t "${TimeoutDHCP:-30}" $options "$Interface"; then

        report_error "DHCP IPv$1 lease attempt failed on interface '$Interface'"

        return 1

    fi

}

Added a line to /etc/netctl/eth0:

TimeoutDHCP=60

Let's see if that does the trick! It's also suggested in https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=46348

ethernet_up() {

    if ! is_interface "$Interface"; then

        report_error "Interface '$Interface' does not exist"

        return 1

    fi

    # Disable IPv6 before bringing the interface up to prevent SLAAC

    if [[ $IP6 == "no" ]]; then

        sysctl -q -w "net.ipv6.conf.${Interface/.//}.disable_ipv6=1"

    fi

    if ! bring_interface_up "$Interface"; then

        report_error "Failed to bring interface '$Interface' up"

        return 1

    fi

    if is_yes "${SkipNoCarrier:-no}"; then

        SkipDAD=yes

    else

        # Some cards are plain slow to come up. Don't fail immediately.

        if ! timeout_wait "${TimeoutCarrier:-5}" '(( $(< "/sys/class/net/$Interface/carrier") ))'; then

            report_error "No connection found on interface '$Interface' (timeout)"

            bring_interface_down "$Interface"

            return 1

        fi

    fi

...

}