unable to ssh to nexus7 after it sits idle

[Paul Larson]

I have some automated test runs that are doing an ssh to a nexus7, dist-upgrade, reboot, then running some tests. After todays tests ran, I tried to connect remotely to one of the devices and though I could ping it, and it appeared to be up and running, I was not able to ssh in. Since they both did this, I didn't think it had anything to do with the individual tests I was running (smem and eventstat). I had someone who had access to the lab go check on it to confirm it was running, and restart it for me. After the restart I was able to ssh in just fine, and rerunning the tests didn't seem to effect this, however idling did. So to reproduce:
1. install openssh-server
2. ssh into the system
3. logout
4. wait a while (10-15 minutes seems to be sufficient)
5. try to ssh in again

This setup is relatively new, but I don't think I had this problem yesterday. On the off chance that one of the updates today might have caused it, here were the things that got updated from my test runner's log:
Get:1 http://ports.ubuntu.com/ubuntu-ports/ raring/main libgomp1 armhf 4.7.2-20ubuntu1 [25.2 kB]
Get:2 http://ppa.launchpad.net/utah/daily/ubuntu/ raring/main utah-common all 0.7ubuntu1-r810~raring1 [25.2 kB]
Get:3 http://ports.ubuntu.com/ubuntu-ports/ raring/main gcc-4.7-base armhf 4.7.2-20ubuntu1 [16.3 kB]
Get:4 http://ppa.launchpad.net/utah/daily/ubuntu/ raring/main utah-client all 0.7ubuntu1-r810~raring1 [79.3 kB]
Get:5 http://ports.ubuntu.com/ubuntu-ports/ raring/main libstdc++6 armhf 4.7.2-20ubuntu1 [271 kB]
Get:6 http://ports.ubuntu.com/ubuntu-ports/ raring/main cpp-4.7 armhf 4.7.2-20ubuntu1 [4,380 kB]
Get:7 http://ports.ubuntu.com/ubuntu-ports/ raring/main libgcc-4.7-dev armhf 4.7.2-20ubuntu1 [167 kB]
Get:8 http://ports.ubuntu.com/ubuntu-ports/ raring/main gcc-4.7 armhf 4.7.2-20ubuntu1 [5,015 kB]
Get:9 http://ports.ubuntu.com/ubuntu-ports/ raring/main libgcc1 armhf 1:4.7.2-20ubuntu1 [48.9 kB]
Get:10 http://ports.ubuntu.com/ubuntu-ports/ raring/main dconf-service armhf 0.15.2-0ubuntu5 [20.9 kB]
Get:11 http://ports.ubuntu.com/ubuntu-ports/ raring/main libdconf1 armhf 0.15.2-0ubuntu5 [22.6 kB]
Get:12 http://ports.ubuntu.com/ubuntu-ports/ raring/main dconf-gsettings-backend armhf 0.15.2-0ubuntu5 [14.0 kB]
Get:13 http://ports.ubuntu.com/ubuntu-ports/ raring/universe linux-image-3.1.10-9-nexus7 armhf 3.1.10-9.24 [5,706 kB]
Get:14 http://ports.ubuntu.com/ubuntu-ports/ raring/main alsa-utils armhf 1.0.25-4ubuntu1 [1,105 kB]
Get:15 http://ports.ubuntu.com/ubuntu-ports/ raring/main ubuntu-drivers-common armhf 1:0.2.75 [31.6 kB]
Get:16 http://ports.ubuntu.com/ubuntu-ports/ raring/main update-notifier armhf 0.130 [51.4 kB]
Get:17 http://ports.ubuntu.com/ubuntu-ports/ raring/main update-notifier-common all 0.130 [201 kB]
Get:18 http://ports.ubuntu.com/ubuntu-ports/ raring/main dconf-tools armhf 0.15.2-0ubuntu5 [63.2 kB]
Get:19 http://ports.ubuntu.com/ubuntu-ports/ raring/main libupower-glib1 armhf 0.9.19-1ubuntu4 [23.9 kB]
Get:20 http://ports.ubuntu.com/ubuntu-ports/ raring/main gnome-settings-daemon armhf 3.6.4-0ubuntu3 [405 kB]
Get:21 http://ports.ubuntu.com/ubuntu-ports/ raring/main sysvinit-utils armhf 2.88dsf-13.10ubuntu15 [54.0 kB]
Get:22 http://ports.ubuntu.com/ubuntu-ports/ raring/main sysv-rc all 2.88dsf-13.10ubuntu15 [44.1 kB]
Get:23 http://ports.ubuntu.com/ubuntu-ports/ raring/main initscripts armhf 2.88dsf-13.10ubuntu15 [27.9 kB]
Get:24 http://ports.ubuntu.com/ubuntu-ports/ raring/main python3-problem-report all 2.8-0ubuntu3 [10.6 kB]
Get:25 http://ports.ubuntu.com/ubuntu-ports/ raring/main python3-apport all 2.8-0ubuntu3 [88.5 kB]
Get:26 http://ports.ubuntu.com/ubuntu-ports/ raring/main apport all 2.8-0ubuntu3 [173 kB]
Get:27 http://ports.ubuntu.com/ubuntu-ports/ raring/main apport-gtk all 2.8-0ubuntu3 [9,922 B]
Get:28 http://ports.ubuntu.com/ubuntu-ports/ raring/main checkbox armhf 0.15.1 [1,413 kB]
Get:29 http://ports.ubuntu.com/ubuntu-ports/ raring/main checkbox-qt armhf 0.15.1 [67.2 kB]
Get:30 http://ports.ubuntu.com/ubuntu-ports/ raring/main libusbmuxd2 armhf 1.0.8-1ubuntu1 [13.5 kB]
Get:31 http://ports.ubuntu.com/ubuntu-ports/ raring/universe linux-headers-3.1.10-9 armhf 3.1.10-9.24 [11.7 MB]
Get:32 http://ports.ubuntu.com/ubuntu-ports/ raring/universe linux-headers-3.1.10-9-nexus7 armhf 3.1.10-9.24 [463 kB]
Get:33 http://ports.ubuntu.com/ubuntu-ports/ raring/main python-problem-report all 2.8-0ubuntu3 [10.6 kB]
Get:34 http://ports.ubuntu.com/ubuntu-ports/ raring/main python-apport all 2.8-0ubuntu3 [89.0 kB]
Get:35 http://ports.ubuntu.com/ubuntu-ports/ raring/main python-ubuntuone-storageprotocol all 4.1.90-0ubuntu1 [63.8 kB]
Get:36 http://ports.ubuntu.com/ubuntu-ports/ raring/universe ubuntu-defaults-nexus7 all 0.49 [9,018 B]
Get:37 http://ports.ubuntu.com/ubuntu-ports/ raring/main ubuntuone-client-gnome armhf 4.1.90-0ubuntu1 [16.7 kB]
Get:38 http://ports.ubuntu.com/ubuntu-ports/ raring/main upower armhf 0.9.19-1ubuntu4 [90.6 kB]
Get:39 http://ports.ubuntu.com/ubuntu-ports/ raring/main usbmuxd armhf 1.0.8-1ubuntu1 [33.5 kB]
Get:40 http://ports.ubuntu.com/ubuntu-ports/ raring/main xserver-common all 2:1.13.2-0ubuntu1 [32.9 kB]
Get:41 http://ports.ubuntu.com/ubuntu-ports/ raring/main xserver-xorg-core armhf 2:1.13.2-0ubuntu1 [1,264 kB]
Get:42 http://ports.ubuntu.com/ubuntu-ports/ raring/main xserver-xorg-video-radeon armhf 1:7.1.0-0ubuntu1 [134 kB]
Get:43 http://ports.ubuntu.com/ubuntu-ports/ raring/main xserver-xorg-video-ati armhf 1:7.1.0-0ubuntu1 [7,080 B]
Get:44 http://ports.ubuntu.com/ubuntu-ports/ raring/main xserver-xorg-video-nouveau armhf 1:1.0.6-0ubuntu2 [83.2 kB]
Get:45 http://ports.ubuntu.com/ubuntu-ports/ raring/main python-dirspec all 4.1.90-0ubuntu1 [6,886 B]
Get:46 http://ports.ubuntu.com/ubuntu-ports/ raring/main rhythmbox-ubuntuone all 4.1.90-0ubuntu1 [6,312 B]

Unfortunately, this is about all I can get at the moment since I don't currently have access to a local nexus7.

[Robert Bruce Park (robru)]

I have a local Nexus7 and I've been able to ssh in after hours of idle time. Even left it idling overnight and then ssh'd in in the morning in order to run updates.

Are there any specific steps you'd like me to try on my nexus7 in order to try to reproduce this?

[Paul Larson (pwlars)]

Did you dist-upgrade to the latest packages today and try it again? I saw two separate nexus 7's do this today

[Robert Bruce Park (robru)]

I don't recall the exact time of day that I last dist-upgraded it, but it was definitely within the last 24 hours. I'll dist-upgrade again, give it acouple hours, then try to ssh in again, and let you know what happens.

[Robert Bruce Park (robru)]

Ok, 2 hours later, with all latest raring packages, I am having no trouble ssh'ing into my nexus7.

[C de-Avillez (hggdh2)]

I just had it. My Nexus was (1) connected to both wireless and (2) USB-connected to my laptop. I left it idle for a while (some 1, 2 hours), and then I was unable to connect via SSH.

Going local I noticed that wlan0 now only had a IPv6 address, and that n-m had lost connection to the AP, and could not reconnect. I am attaching the syslog.

Not sure yet on causes.

[C de-Avillez (hggdh2)]

A chat with rfowler indicates that the two nexus failing are indeed USB-connected to a computer; the one that is *not* failing is not USB-connected.

[Oliver Grawert (ogra)]

try shutting down teh usb0 interface right after boot (sudo ifconfig usb0 down) and see if the issue still persists, it could be that NM is going mad over the usbnet connection that is estabished when USB is connected to a PC so we need to make sure the interface doesnt come up automatically.

[Paul Larson (pwlars)]

I don't have access to a local nexus7 at the moment to try this on, but maybe you can do this carlos? I did try having rick unplug the usb cable from the nexus 7 devices in the lab and have them get power from the wall rather than usb from a computer and I'm not having this problem anymore with those. So it seems like at some point after boot, the usb network device is affecting things.

[Robert Bruce Park (robru)]

Marking incomplete because pwlars found a workaround and hggdh2 hasn't responded (also I don't think he works for us any longer...)