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Boot

Rotate screen
echo 1 > /sys/class/graphics/fbcon/rotate_all

Wifi setup
iwctl --passphrase <psk> station wlan0 connect <essid>

NTP
timedatectl set-ntp true

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Set up a ssh tunnel only user

In order to give someone access to hosts that are available only by ssh "bouncing" (ProxyJump), add a user for this specific purpose.

We have an internal openstack where instances get IPs on per-tenant networks. Each tenant has a 'bastion' host that has a "public" ip (floating ip). You can access other instances by bouncing through the bastion. From time to time I want to let someone else into an instance. This could be done either with:

a.) just give them shell access to the bastion and let them hop through. Sharing an unrestricted shell account on my bastion is less than ideal. b.) assign a floating/"public" IP to the instance so they could go directly in. Floating IPs are limited, so this is less than ideal.

So instead, I have set up a single user as described here that can only be used for ProxyJump. It allows others proxied access to my instances but without granting them full shell access.

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Setting up Docker with user namespaces on CentOS 7.4

The procedure below has been tested on a Digital Ocean VM with CentOS 7.4

# Install docker from RHEL’s standard repos
yum install -y docker

#
# We’ll activate the ‘user namespaces’ feature that defends against

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[INFO] 
[INFO] ------------< it.rcs.community.renderer:community-renderer >------------
[INFO] Building VMS Services for RCS (Video Platform) 1.0.0-BUILD-SNAPSHOT
[INFO] --------------------------------[ war ]---------------------------------
Downloading from central: https://repo.maven.apache.org/maven2/org/jvnet/jaxb2/maven2/maven-jaxb2-plugin/maven-metadata.xml
Downloaded from central: https://repo.maven.apache.org/maven2/org/jvnet/jaxb2/maven2/maven-jaxb2-plugin/maven-metadata.xml (918 B at 2.4 kB/s)
Downloading from central: https://repo.maven.apache.org/maven2/org/restlet/jee/org.restlet.ext.spring/2.3.1/org.restlet.ext.spring-2.3.1.pom
[WARNING] The POM for org.restlet.jee:org.restlet.ext.spring:jar:2.3.1 is missing, no dependency information available
Downloading from central: https://repo.maven.apache.org/maven2/apache-beanutils/commons-beanutils/1.7.0/commons-beanutils-1.7.0.pom
[WARNING] The POM for apache-beanutils:commons-beanutils:jar:1.7.0 is missing, no dependency information available

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LVM snapshots are logical volumes that reflect the state of the snapshoted volume at the exact moment in time the snapshot was created. Useful for backups and reference points we can revert back to.

Creating snapshots

$ sudo lvcreate --size 5G --snapshot --name root-backup /dev/vg0/root
  Logical volume "root-backup" created.

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curl -X PUT -T ./{file.dat} -H "x-ms-date: $(date -u)" -H "x-ms-blob-type: BlockBlob" "https://{storageaccount}.blob.core.windows.net/backups/{file.dat}?{sas-token}"

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[Unit]
Description=Nodejs Web Application MyAPP
After=syslog.target network.target

[Service]
TimeoutStartSec=300

WorkingDirectory=/opt/nodejs/MyAPP/app

User=nodejs

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sub vcl_recv {
  if (req.http.X-Forwarded-Proto !~ "https") {
    return (synth(850, "Moved Permanently"));
  }
}

sub vcl_synth {
  if(resp.status == 850) {
    set resp.http.Location = "https://" + req.http.host + req.url;
    set resp.status = 301;

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This is a note on how to cross compile opencv for pretty much any ARM device(HardFP supported in this case) and deploy. Native
compiling in ARM devices can be painfully slow and they seem to hang often during build(mine got stuck at 43%). So if you happen
to have a desktop/laptop/server running ubuntu or similar linux distro, u can build opencv in fractionth of the time taken for 
native compiling without any issues.
Building opencv3 with TBB and NEON and VFP support can boost opencv performance. Thanks to Adrian at pyimagesearch for pointing 
that out.
Both my PC and target machine aka orange pi zero are running ubuntu 16.04 with python2.7 and python 3.5.
Let us use the term "build machine" for your PC where you are building opencv and "target machine" for the ARM single board computer.

1.Run the following commands in both machines(I think installing these in target machine only would do) to install the necessary libraries etc.(mine worked with them,so they should be enough 

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# Let apache know we're behind a SSL reverse proxy
SetEnvIf X-Forwarded-Proto "https" HTTPS=on

# Redirect to HTTPS
<IfModule mod_rewrite.c>
  RewriteEngine on
  RewriteCond %{HTTPS} !=on
  RewriteCond %{HTTP:X-Forwarded-Proto} !https [NC]
  RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
</IFModule>