Tag Archives: Linux

systemd automatic restart on failure

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I had an issue with apache web server recently where the service was crashing. A simple poor mans fix was to make use of systemd’s ability to automatically restart a failed service

At first I located the systemd unit file with systemctl status httpd

I then edited the file with vi /usr/lib/systemd/system/httpd.service

Under the [Service] block I then added the restart variables

[Service]

# Auto-restart
Restart=on-failure
RestartSec=5s

I then reloaded systemd with systemctl daemon-reload

Generate ppk files for all existing keys

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Recently I did an automation task involving the automated generation of ppk files when ssh-keygen is run. I also wanted to generate ppk files for the existing keys on this machine.

The command I ended up using, to generate a ppk file for every /home/*/.ssh/id_rsa file was:

set -x;for user in $(find /home/*/.ssh -name id_rsa -type f);do puttygen ${user} --ppk-param version=2 -o ${user}.ppk;chown $(ls -l ${user} | awk '{print $3":"$4}') ${user}.ppk;chmod 600 ${user}.ppk;done;set +x

Replacing telnet with netcat

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A stupid post it note for my own benefit mostly. My employer refuses to allow telnet on any of their machines, citing audit compliance and the pre-existance of netcat

So to test that a port is open with netcat you run:

nc -zv victim.host.com 8080

Enable epel-release and PowerTools on Oracle Linux 8

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I’ve been trying out Oracle Cloud, particularly the “Always Free” offering as it permits free hosting for up to 6 virtual machines. This then got me trying Oracle Linux as an OS.

Oracle Linux is based on CentOS and has alot of similarities but some small differences. CentOS’s epel-release and PowerTools repos are of course, Oracle branded and not installed by default.

Enable epel-release

dnf install oracle-epel-release-el8
dnf config-manager --set-enabled ol8_developer_EPEL
dnf update

Enable PowerTools

dnf config-manager --set-enabled ol8_codeready_builder