After upgrade Ubuntu would only boot readonly.

1.  First check to see the uuid entered in /etc/fstab:
cat /etc/fstab revealed that the original uuid was different then the current uuid

2. Check to see what the current UUID is showing up as:
blkid

3. If the UUID does not match, remount the filesystem to the new UUID and change fstab:

mount -rw -o remount UUID=6ccc9680-2706-41e1-896a-b347cab0ba7e /

vi /etc/fstab to replace the  UUID

4. Reboot

By: Timothy Conrad

If you receive an error similar to this:
An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://dl.google.com/linux/earth/deb stable Release: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 1397BC53640DB551
W: Failed to fetch http://dl.google.com/linux/earth/deb/dists/stable/Release.gpg The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 1397BC53640DB551
W: Some index files failed to download. They have been ignored, or old ones used instead.

You can easily remedy this problem by updating Google’s signature:
wget -q -O – https://dl-ssl.google.com/linux/linux_signing_key.pub | sudo apt-key add –

By: J Santos
Example by: Timothy Conrad

List available timezone locations

Type: timedatectl list-timezones

Africa/Abidjan
Africa/Accra
Africa/Addis_Ababa
Africa/Algiers
Africa/Asmara
…
…
…
America/New_York

set timezone

Type:  timedatectl set-timezone America/New_York

display settings

Tyep: timedatectl
Local time: Fri 2017-06-21 16:10:07 EDT
Universal time: Fri 2017-06-21 07:10:07 UTC
RTC time: Fri 2017-07-21 07:10:06
Time zone: America/New_York (EDT, -0400)
Network time on: yes
NTP synchronized: yes
RTC in local TZ: no

Knockd was causing me a headache with the error “command returned non-zero status code (1)” when running with their stock init.d setup.

Rather than troubleshooting their bug I decided to create my own service that would start using the /usr/sbin/knockd directly.

Step (1) Create the startup script
nano /etc/systemd/system/knockd-security.service

[Unit]
Description=knockdservice
After=network-online.target

[Service]
Type=idle
ExecStart=/usr/local/bin/knockd-security.sh

[Install]
WantedBy=default.target

Ctrl X
y

chmod 664 /etc/systemd/system/knockd-security.service

Step (2) Create the startup shell script
nano /usr/local/bin/knockd-security.sh
#!/bin/bash
/usr/sbin/knockd

Ctrl X
y

chmod 744 /usr/local/bin/knockd-security.sh

Step(3) Finalization
systemctl daemon-reload
systemctl enable knockd-security.service

Step(4) Test before reboot
systemctl start knockd-security.service

Step(5) Reboot
reboot

By: Timothy Conrad

SSH won’t start at boot on Kali 2.0?

Don’t worry, it’s because Kali 2.x is based on Debian 8, as opposed to Kali 1.x being based on Debian 7.

Kali 1.x uses init/update-rc.d;
For Kali 1.x, the command is

update-rc.d ssh enable

Kali 2.x uses systemd/systemctl
For Kali 2.x, the command is

systemctl enable ssh.service

By: Security Jedi, S. Chaudhary
Modified by: Timothy Conrad