How to add PHP support for jailed SSH users in ISPConfig 3

Jailkit is an easy to use tool to create and maintain jail environments for shell users on Linux. In this guide, I will show you how to move PHP and its dependencies into the jail so that the jailed user can execute PHP scripts inside the jail.
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How to list installed packages on Debian?

To get a list of all installed packages on a Debian or Ubuntu server, run the command:

dpkg --get-selections

This command will show you a rather long list. To save the list to a file, use this command:

dpkg --get-selections > /tmp/packages.txt

the list is saved then in the file /tmp/packages.txt.

If you seek for a specific package, use the grep command:

dpkg --get-selections | grep nginx

will show you all packages that contain the word "Nginx" in their name.

Example:

root@sv1:/# dpkg --get-selections | grep nginx
nginx-common                                    install
nginx-extras                                    install

How To Check And Repair All MySQL Databases on Debian And Ubuntu Linux

The Following command can be used to check and repair all MySQL databases on a Ubuntu or Debian Linux System.

Ubuntu Linux

sudo mysqlcheck --defaults-file=/etc/mysql/debian.cnf --auto-repair --optimize --all-databases

Debian Linux

mysqlcheck --defaults-file=/etc/mysql/debian.cnf --auto-repair --optimize --all-databases

The benefit of the above command is that it uses the debian-sys-maint login to MySQL which is available on every Debian and Ubuntu System, so you don't have to provide the MySQL root login details.

How to Copy Files with SCP between Linux Servers

1.1 SCP Command Line-An Overview

 

The SCP command line is commonly used to copy files over SSH, and between popular Operating systems like Linux, Mac and Windows in a secure fashion. SCP is used to copy files to/from a remote server. It also allows you to copy files from one remote server to another remote server, without passing traffic through your PC.

Continue reading How to Copy Files with SCP between Linux Servers

Solution for: fatal: open database /var/lib/postfix/smtpd_scache.db: File exists

If your mail server stops working (neither incoming nor outgoing email works) and you find the following error message in the mail.log file:

fatal: open database /var/lib/postfix/smtpd_scache.db: File exists

then the smtpd_scache.db might got corrupted. Postfix will recreate this file if it does not exist. So it can be removed to solve the issue:

/etc/init.d/postfix stop
rm -f /var/lib/postfix/smtpd_scache.db
/etc/init.d/postfix start

Thanks to Alexander Fox for sending me this FAQ.

Solution for dovecot error: /path/ is no longer mounted. If this is intentional, remove it with doveadm mount

Dovecot is watching the whole server filesystem for modifications and removed or added sub filesystems. If you get errors similar to this one on your server:

Aug 30 09:10:23 server1 dovecot: master: Warning: /var/www/clients/client1/web1/log is no longer mounted. If this is intentional, remove it with doveadm mount

 (the directory path may vary), then you can fix it by excluding the path from being watched by dovecot. In my case, dovecot shall not watch my website directories as they do not contain any mailboxes

Run the following command on the shell as root user:

doveadm mount add '/var/www/*' ignore

To exclude all files and folders in /var/www from deovecot monitoring.

 

Solution for amavisd error – TROUBLE in process_request: Error writing a SMTP response to the socket: Broken pipe – on OpenVZ server

If you get error messages from amavisd similar to the one posted below on a server which is virtualized with OpenVZ:

Mar  5 09:09:02 v100 amavis[17378]: (17378-14) (!!)TROUBLE in process_request: Error writing a SMTP response to the socket: Broken pipe at (eval 100) line 987, <GEN44> line 31.

then the issue can be caused by the NUMTCPSOCK value in the openvz limits. Even if the barrier of this limit was never met in /proc/user_beancounters, the above error occurs when more then 25% of all TCP sockets were used. The solution is to set the NUMTCPSOCK barrier and limit to a high value in the openvz container configuration file. Here a value that worked for me on a moderately used mailserver:

NUMTCPSOCK="2000:2000"

Finally restart the OpenVZ VM to apply the new limit value.

 

Apache mod_security settings for WordPress and ModX

If you use the apache mod_security module on your apache server, you might encounter wrong 403 errors for several URL's of the cms systems. Here are some exception rules to avoid that:

For WordPress Blogs

<locationmatch "/wp-admin/admin-ajax.php">
SecRuleRemoveById 300013
SecRuleRemoveById 300015
SecRuleRemoveById 300016
SecRuleRemoveById 300017
</locationmatch>

<locationmatch "/wp-admin/page.php">
SecRuleRemoveById 300013
SecRuleRemoveById 300015
SecRuleRemoveById 300016
SecRuleRemoveById 300017
</locationmatch>

<locationmatch "/wp-admin/post.php">
SecRuleRemoveById 300013
SecRuleRemoveById 300015
SecRuleRemoveById 300016
SecRuleRemoveById 300017
</locationmatch>

For the ModX CMS

<LocationMatch "/manager/index.php">
SecRuleRemoveById 300016
</LocationMatch>

<LocationMatch "/connectors/resource/index.php">
SecRuleRemoveById 300013 300014 300015 300016
</LocationMatch>

<LocationMatch "/connectors/element/tv.php">
SecRuleRemoveById 300013 300016
</LocationMatch>

Add these rules inside the vhost file of the website. If you use ISPConfig to manage the server, then add the rules in the apache directives field of the website settings in ispconfig.

Many thanks to PlanetFox for providing the rules.

How to disable MySQL replication on master/master andmaster/slave setups

The following guide shows how to disable and remove mysql replication from two or more mysql servers. These steps can be used for master/slave and master/master mysql setups. The following SQL commands have to be be executed in phpmyadmin or with the mysql commandline program. It is just important that you are logged in as mysql root user. Below I will use the mysql commandline client.

Login into mysql as root user from commandline:

mysql -u root -p

the mysql command will ask for the mysql root password.

Then execute these commands if the installed mysql version is < 5.5.16:

STOP SLAVE;
RESET SLAVE;
QUIT

use the commands below instead if the mysql version is > 5.5.16

STOP SLAVE;
RESET SLAVE ALL;
QUIT

Now edit the my.cnf file (/etc/mysql/my.cnf) and add a # in front of all lines that start with "replicate-" or "master-". Example:

# replicate-same-server-id = 0
# master-host = 192.168.0.105
# master-user = slaveuser
# master-password = akst6Wqcz2B
# master-connect-retry = 60

Then restart mysql:

/etc/init.d/mysql restart