Started getting the following error while running ./validate.php for LibreNMS
Cannot load Zend OPcache - it was already loaded
Looks like the problem arises out of PHP trying to load two ini files for OPcache. Was trying to enable OPcache for LibreNMS so I created an opcache.ini file and put the settings in it. I missed the default 10-opcache.ini file.
Moving all the settings into the 10-opcache.ini file and deleting the created opcache.ini file resolved the issue for me.
Below are some simple commands around working with UFW. UFW is included in Ubuntu. However it may need to be enable.
sudo ufw status
sudo systemctl stop ufw && sudo systemctl disable ufw
sudo systemctl stop ufw
sudo systemctl stop ufw
sudo ufw enable
sudo ufw allow 22/tcp
sudo ufw status numbered
Example output
sudo ufw status numbered Status: activeTo Action From-- ------ ----[1] 3478/udp ALLOW IN Anywhere [2] 5514/udp ALLOW IN Anywhere [3] 8080/tcp ALLOW IN Anywhere [4] 8443/tcp ALLOW IN Anywhere [5] 8880/tcp ALLOW IN Anywhere [6] 8843/tcp ALLOW IN Anywhere [7] 6789/tcp ALLOW IN Anywhere [8] 27117/tcp ALLOW IN Anywhere [9] 22/tcp ALLOW IN Anywhere
You need to know the number of the rule you want to delete. Replace number with the number of the rule from the status command
sudo ufw delete number
sudo ufw reset
Allow access to port from specific IP address
Example command allows access to SSH (port 22) from the 172.16.0.0/12 ip range.
sudo ufw allow proto tcp from 172.16.0.0/12 to any port 22
One note: It appears that you need to run the rule with every IP range you want to allow.
Allow access to port from all private IP ranges (RFC 1918)
If we wanted to allow SSH (port 22) from all local IP addresses, we would need to run the following three commands.
sudo ufw allow proto tcp from 10.0.0.0/8 to any port 22 sudo ufw allow proto tcp from 172.16.0.0/12 to any port 22 sudo ufw allow proto tcp from 192.168.0.0/16 to any port 22
The following link has more information regarding UFW firewall and subnets.
https://www.cyberciti.biz/faq/ufw-allow-incoming-ssh-connections-from-a-specific-ip-address-subnet-on-ubuntu-debian/
Find UUID
blkid
Example output
/dev/xvdb1: UUID="42fbe9a1-eea1-34bc-439d-19a0b48e7df1" TYPE="xfs"
Mount drive using the UUID
[root@host ~]# mount -U 42fbe9a1-eea1-34bc-439d-19a0b48e7df1 /mnt
Add to fstab to automatically mount on system boot up
vi /etc/fstab
Add the following, swap out the UUID for your devices UUID
UUID="42fbe9a1-eea1-34bc-439d-19a0b48e7df1" /backup xfs defaults 0 0
Save and exit. Now when the system reboots it should automatically mount the drive. You should also be able to call “mount -a” to automatically mount everything in fstab.
You can install the default-jre to get the default Java package installed
sudo apt install -y default-jre
Error when trying to ping
ping: socket: Operation not permitted
Looks like it is a permissions issue. To resolve it, find where your ping binary is and change the permissions on it
sudo chmod 4711 /usr/bin/ping
Example:
$ which ping
/usr/bin/ping
$ sudo chmod 4711 /usr/bin/ping
$ ping incredigeek.com
Screen is a handy tool that can help you run scripts on servers remotely without having to worry about the session getting terminated. It seems to operate kinda like a virtual console.
Create a new session with a specified name
screen -S SessionName
Example output below. Create session named testsession and print screen sessions.
[bob@localhost imapsync]$ screen -S testsession [bob@localhost imapsync]$ screen -ls There are screens on: 3313.testsession (Attached) 1 Sockets in /var/run/screen/S-bob. [bob@localhost imapsync]$
You can disconnect from a screen session by hitting ctrl + a and then ctrl +d
“ctrl + a” then “ctrl + d”
You can list the screen sessions with
screen -ls
Example
[bob@localhost imapsync]$ screen -ls There are screens on: 3212.testsession (Detached) 2556.xap (Detached) 2 Sockets in /var/run/screen/S-bob. [bob@localhost imapsync]$
You can reconnect to a screen session with
screen -r testsession
To terminate a screen session, connect to that session and then on a clear line hit ctrl + d
Same way as if you were closing a remote ssh connection.
Looks like you can use Darling to run MacOS command line applications in Linux.
Bunch of tweaks and enhancements are on the arch wiki
https://wiki.archlinux.org/index.php/Firefox/Tweaks
Two specific ones that can help with performance are enabling OMTC and WebRender
https://wiki.archlinux.org/index.php/Firefox/Tweaks#Enable_OpenGL_Off-Main-Thread_Compositing_(OMTC)
Open up Firefox and about:config
Search for “layers.acceleration.force-enabled”
Search for “gfx.webrender.all” and set to true
Restart Firefox.
The regular command to reset the password for a NextCloud user does not work when NextCloud is installed from a snap package.
$ sudo -u www-data php /var/www/nextcloud/occ user:resetpassword admin Could not open input file: /var/www/nextcloud/occ
The reason is that NextCloud is located in “/snap/nextcloud”
Unfortunately the occ file is not located in /snap/nextcloud/current/
However, you can run the nextcloud.occ command directly without specifying the path. Change admin to your user.
sudo nextcloud.occ user:resetpassword admin
Type in the new password twice and login.
Helpful links
https://wiki.archlinux.org/index.php/Fan_Speed_Control#Dell_laptops
https://bbs.archlinux.org/viewtopic.php?id=248106
https://www.reddit.com/r/Dell/comments/9pdgid/configuring_the_xps_to_play_nice_with_linux
You can use the following commands to “initilize” the fans so the fancontrol can read them.
sudo modprobe dell-smm-hwmon ignore_dmi=1sudo sensors-detect
After that is done you should be able to setup a fancontrol config with
sudo pwmconfig
After it is set up you can launch fancontrol to control the fans
sudo fancontrol
If you want to tweak the setting, modify the fancontrol config under
/etc/fancontrol
or run pwmconfig again and replace config.
Sounds like you should be able to add the following to “etc/modprobe.d/dell.conf” to get it to run on boot.
options dell-smm-hwmon ignore_dmi=1