Can’t build or push docker container?

Error:

oci runtime error: applying cgroup configuration for process caused mountpoint for devices not found

Try restarting docker. If you then get:

Error starting daemon: Devices cgroup isn't mounted

Then it may be time to shutdown and cold-start the machine.

In my case, I didn’t have to install or config anything new. Docker was running fine before this failure. Try restarting docker (eg. systemctl restart docker). If it fails, shutdown and cold-boot the machine. Ensure docker is running. After 129 days of uptime, my docker just got in a weird, bad state.

See also:

https://stackoverflow.com/questions/32002882/error-starting-docker-daemon-on-ubuntu-14-04-devices-cgroup-isnt-mounted/55657451

 

NOTE! Don’t follow this article, just use Eternal Terminal (et) instead of mosh (and instead of ssh).  It works flawlessly with iTerm2 and tmux.

I have found terminal/shell nirvana on my Mac with mosh + tmux + iTerm2 Tmux Integration, but it wasn’t easy.

My dream setup was these 3 running together:

1) mosh: Runs on client and on server. An ssh replacement that is secured with AES-128 and ssh. Virtually indestructible ssh-like sessions that remain “live” even after you change IP addresses (ie. physical locations), VPNs, or network interfaces. I can login to a server and never need to re-login for *months*. Whenever I open my macbook, my shell sessions are exactly where they were before and ready for the next command.  If your IP address changes while you commute (eg. train) or you are on VPN a lot, you really should use mosh instead of ssh. It’s not just for unreliable connections, I use mosh everywhere because it saves me time.

2) tmux: Runs on the server. Replacement for the old ‘screen’ utility. It allows you to keep active windows (and panes) in a session that remains alive even after you disconnect from the remote server.

3) iTerm2’s Tmux Integration: Runs on Mac. Very cool iTerm2 feature that renders your tmux windows as native iTerm2 tabs. Allows you to scroll back through your tmux window with Macbook touchpad gestures and iTerm hotkeys. Supports iTerm2’s very quick & capable Cmd-F (Find) instead of tmux’s Find.  Supports intuitive text selection and advanced text selection (discontiguous select & copy) built into iTerm. Switching between tabs with keyboard shortcuts. Basically everything you can do in iTerm2 regular tabs, you can probably do with your tmux session rendered by iTerm2’s Tmux Integration. It rocks.

 

The Problem

The problem is iTerm’s Tmux integration works fine when using ssh, but not when using mosh.

 

The Solution

With this howto, you can build a patched version of mosh (client and server) that is compatible with iTerm’s Tmux Integration.  Mosh is a small program, so the build is very quick.

Moreover, this howto allows you to try the patched mosh binaries without touching your existing mosh installation. This is done by specifying the ‘–client’ and ‘–server’ options when running mosh.

Once you are happy with how the patched mosh is working, you can move the patched mosh to a location in your path (need to do this on both client and server).

Note, if you are on wifi all the time, you can use Eternal Terminal instead of this howto. I use hard-wired ethernet at my desk and wifi when I leave my desk (eg. walking to a meeting). It so happens, this switching of network interfaces seems to break Eternal Terminal and close my session (in my testing).

In my setup I have a macbook (mosh client) connecting to an ubuntu 16.04 server (mosh server).

First, we’ll build mosh on the Macbook (mosh-client).

 

Build patched mosh-client on Macbook

Create a directory for the code:

dlee-mbp:~ donn$ mkdir -pv ~/workspace/git/github.com/rledisez/

dlee-mbp:~ donn$ cd ~/workspace/git/github.com/rledisez/

Grab the code:

dlee-mbp:rledisez donn$ git clone https://github.com/rledisez/mosh.git

dlee-mbp:rledisez donn$ cd mosh

Checkout the patched mosh branch called “localScrollback-1.3.2”:

dlee-mbp:mosh donn$ git checkout -b localScrollback-1.3.2 origin/localScrollback-1.3.2

 

Use Homebrew to install dependencies:

dlee-mbp:mosh donn$ brew install protobuf automake pkg-config

 

Build patched mosh binaries:

dlee-mbp:mosh donn$ ./autogen.sh

configure.ac:21: installing ‘./ar-lib’

configure.ac:13: installing ‘./compile’

configure.ac:6: installing ‘./install-sh’

configure.ac:6: installing ‘./missing’

src/crypto/Makefile.am: installing ‘./depcomp’

parallel-tests: installing ‘./test-driver’

 

./configure

<See many lines of output>

 

make

<See many lines of output>

 

You don’t have to do ‘make install’ at this point. You can try the binary without installing it (see below).

 

But, we also need a patched mosh on the server, so next…

 

Build mosh on ubuntu server

Install debian package dependencies:

Note: Boost (libboost-dev) not needed for mosh 1.2+ so I didn’t install it.

sudo apt-get install automake libtool g++ protobuf-compiler libprotobuf-dev libutempter-dev libncurses5-dev zlib1g-dev libio-pty-perl libssl-dev pkg-config

Build mosh-client and mosh-server:

git clone https://github.com/rledisez/mosh.git

cd mosh

git checkout -b localScrollback-1.3.2 origin/localScrollback-1.3.2

./autogen.sh

./configure

make

 

Again, you don’t have to ‘make install’ if you just want to try things out.

 

Running the patched mosh

Locate the path to patched mosh-client on my Macbook:

/Users/donn/workspace/git/github.com/rledisez/mosh/src/frontend/mosh-client

Locate the path to patched mosh-server on my ubuntu server:

/home/donn/workspace/github.com/rledisez/mosh/src/frontend/mosh-server

 

With this info, I can try my first iTerm + tmux + mosh session:

The ‘mosh’ command is found in the ‘scripts’ subdirectory of the source code directory.

 

dlee-mbp:mosh donn$ scripts/mosh \
--client=/Users/donn/workspace/git/github.com/rledisez/mosh/src/frontend/mosh-client \
--server=/home/donn/workspace/github.com/rledisez/mosh/src/frontend/mosh-server 10.1.1.1

 

After logging in to 10.1.1.1, start tmux on remote host:

remote_host$ tmux -CC

[or ‘tmux -CC a’ if resuming an existing tmux session]

 

… and then see iTerm2 window with Tmux Integration enabled.  Cmd-T to open a new tab.

Enjoy!

 

Switching to patched mosh permanently

 

Mac: Just put mosh and mosh-client in your path.  To see your installed version of mosh:

$ which mosh

$ which mosh-client

 

To see your path:

$ echo $PATH

 

Maybe copy your originals as mosh.orig, mosh-client.orig

 

Ubuntu server: Same thing but with mosh-server.  Maybe save your original as mosh-server.orig

 

From this point forward, be aware that normal, standard mosh clients will not be compatible with patched mosh on the server.  If you want to support both, then use the ‘–server’ option when starting a mosh session to specify which version of mosh-server will be run on the server (eg. mosh-server or mosh-server.orig).

 

Fixing Problems

 

If your session dies abruptly with an error like the following, it means your mosh-client or your mosh-server is not running the patched version of mosh; it is probably running your normal, installed version of mosh.

 

Assertion failed: (*i == *my_it), function diff_from, file user.cc, line 69.

Abort trap: 6

 

Resources

 

iTerm2’s Tmux Integration:

https://gitlab.com/gnachman/iterm2/wikis/TmuxIntegration

 

Build instructions for mosh:

https://github.com/mobile-shell/mosh/wiki/Build-Instructions

 

Patched mosh that supports tmux control-mode (tmux -CC). Original patch by github user 4ast. Rebased on mosh 1.3.2 by rledisez:

https://github.com/rledisez/mosh/tree/localScrollback-1.3.2

At the time of this article, v1.3.2 was the latest stable version for download at mosh.org

 

Original patched mosh:

https://github.com/4ast/mosh

Note: Commit d5bd1d31d86d4003705e69f87466aa7e10f9c5b9 “add support for resize events” is already part of mosh mainline.

 

“tmux integration hangs when logged in with mosh (ok w/ ssh)”

https://gitlab.com/gnachman/iterm2/issues/5924

 

Homebrew package manager for Mac:

https://brew.sh/

Bounty ($$$) for adding tmux control-mode support to mosh:

https://www.bountysource.com/issues/2052677-mosh-prevents-the-use-of-scrollback

 

 

This might be helpful for people like me who recently started learning Postfix:
If you want to eliminate the “red padlock” icon in Gmail, you do not need to get a certificate. Mail servers like Gmail don’t require you to have a certificate (aka client certificate) to connect to them over a secure TLS connection, and subsequently send mail to them (however, things like SPF TXT records and DKIM are needed to avoid Gmail marking your mail as spam).

To send mail to Gmail (and others) with TLS and get rid of the “red padlock”, you only need:

smtp_tls_security_level = may
smtp_tls_loglevel = 1
smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt

…in /etc/postfix/main.cf

TLS-security-level “may” (“You *may* use TLS”) means your mail will be relayed even if the other mail server lacks TLS.  This is represented by the BLUE arrow in the diagram showing mail sent to “example.com”. In other words, such mail will be sent unencrypted, but it will successfully reach example.com.

“smtp_*” are the parameters for the Postfix SMTP Client (the code that talks to public Internet mail servers like Gmail’s mail servers). The “smtpd_*” parameters are for the Postfix SMTP Server (the code that your users connect to when they need to send email to Gmail or some other public Internet mail server).

Make sure ca-certificates.txt exists in postfix’s chroot “jail” (on my ubuntu server it was: /var/spool/postfix/etc/ssl/certs/ca-certificates.crt). This is a database of certs of well-known CAs that your postfix server needs to know when it connects to Gmail (or other mail server). When your postfix server connects to Gmail, Gmail will present to postfix *Gmail’s server cert*, and that server cert will be signed by one of these well-known CAs.

I’m running postfix 2.11.0 on ubuntu 14.04.

You may configure smtp_tls_ciphers and smtp_tls_protocols, but the defaults are OK and recommended. The default for smtp_tls_ciphers is ‘medium’. If you do ‘high’, there’s a (small) chance some of your mail won’t reach destinations that don’t support the strongest ciphers. The default for smtp_tls_protocols is ‘!SSLv2, !SSLv3’ (disable SSL v2 and v3), which is considered safe; it allows TLSv1.

Svenn (https://www.svennd.be) wrote very helpful articles about how to use LetsEncrypt. Such certs are needed when *your* remote users (email clients) need to connect to your postfix server over a secure TLS connection. That’s another article.

Problem: With correct login and password, and correct SMTP settings for Gmail SMTP, owncloud “Test email settings” button fails with:

• A problem occurred while sending the email. Please revise your settings. (Error: Failed to authenticate on SMTP server with username “bob@gmail.com” using 1 possible authenticators)

Other symptom (and hint): Gmail login works fine at other locations, home vs. work, for example.

First, in your gmail account settings, change the “Allow less secure apps” setting to ON. This is found at https://myaccount.google.com in section “Signing in to Google”. NOTE: This makes your gmail account less secure so you might want to create a throwaway gmail account just for SMTP (that’s what I did). I would not use my valuable gmail accounts:

• Allow less secure apps: ON

Other things to check:

• Ensure your owncloud user profile (not owncloud admin settings, but your actual user’s account) has an email address set. This address will receive email from owncloud for password reset email messages and email notifications.  Find your user profile in the upper-right part of the web interface: your_name > Personal.

OwnCloud admin config for smtp:

Send mode: smtp
Encryption: TLS
From address: bob
@ (domain): gmail.com
Authentication method: Login
Authentication required: [checked]
Server address: smtp.gmail.com
: (port) 587
Credentials: bob@gmail.com, mypassword

If you don’t use the webui, Owncloud’s {$owncloud_dir}/config/config.php has these text configuration lines for smtp:

 'mail_smtpmode' => 'smtp',
 'mail_smtpsecure' => 'tls',
 'mail_from_address' => 'bob',
 'mail_domain' => 'gmail.com',
 'mail_smtpauthtype' => 'LOGIN',
 'mail_smtpauth' => 1,
 'mail_smtpport' => '587',
 'mail_smtphost' => 'smtp.gmail.com',
 'mail_smtpname' => 'bob@gmail.com',
 'mail_smtppassword' => 'mypassword',

Still doesn’t work?  I had to also do the following:

Basically, google is smart and treats logins from different geographical locations with different security restrictions (blocks).  In my case, my owncloud server was a VPS thousands of miles away from my laptop location.  So I guessed that google didn’t like that some random location (my vps) was trying to access my gmail account (even though I had “Allow less secure apps” enabled.

I found a big hint that you can “unlock” or re-auth your google account with the following url:

https://accounts.google.com/UnlockCaptcha

So basically, to prove to google that my VPS’s IP address is legit, I had to do this UnlockCaptcha from my VPS. BUT, I have no web browser (gui) on my VPS!  Except for ‘lynx’, the shell/cli based web browser!  Lynx does work for passing the UnlockCaptcha url 🙂

#

Problem: SSG5 (SSG 20) doesn’t upgrade via it’s usb port and reports error “USB flash is not existed. Please insert USB first!”

Solution: You need to use a usb flash drive/stick that is 4GB OR SMALLER!  And formatted FAT (aka FAT16).  FAT32 will probably work too (I haven’t tried).

More detail:

If you are on the SSG’s console, you will see the following error if you attempt to use a usb flash device bigger than 4GB:

“Usb disk size is larger than 4G.Mount failed!”

When you use a 4GB or smaller usb flash disk, you will see success:

“usb device (usb) ready.”

Again, this is on the SSG’s console.

Then you can upgrade via usb (put the *unzipped* screenos image in the *root* directory of the FAT usb drive):

ssg5-> save soft from usb ssg5ssg20.6.3.0r21.0 to flash

Then reboot:

ssg5-> reset

SSG5/SSG20 is a legacy Netscreen ScreenOS firewall/router.