To prevent ssh from disconnecting while idle, add the following to ~/.ssh/config:
Host *
ServerAliveInterval 30
TCPKeepAlive noThis solution is alse useable in any Linux/BSD/*nix environment. If you want to implement this not only on your own user, as a sysadmin, add the above to /etc/ssh/ssh_config instead.
WordPress just showing a white page means it is experienceing PHP errors. When it occurs after a site has been moved from one hosting to another it can be caused by several reasons.
To make it possible to track down the cause you can temporarily add the following to the .htaccess file in the root. If this gives you a internal server error 500 it means it is not allowed by the host. If allowed, you will get error messages from PHP dispayed on screen when accessing the site:
php_flag display_startup_errors on php_flag display_errors on
If you see more or less normal output from the site but once in a while you see lines ending with ?>. This can happen if the site has been running on PHP 5 where the short PHP start tag <? is allowed (instead of the longer <?php.
If the site has been moved to PHP 7 where this is not longer allowed, it can cause this kind of strange behaviour.
If you don’t want to go through all the code and find all the occurrences of <? and replace them with <?php (which is one solution), you can simply add the following to your php.ini:
short_open_tag=On
You need to restart Apache after this.
You need to manually edit the system specific paths in the following files:
The file wp-content/advanced-cache.php contains system specific paths. You can manually update them or just simply delete the file and login to wp-admin of the site and it will be recreated automatically with the correct paths.
Check that both tables have the same engine type, so there isn’t a mix of for example MyISAM and InnoDB.
When it is not possible to delete a file using rm even when logged in as root or by using sudo, check the file attributes with:
lsattr filename.ext
If it has the “i” attribute, this is preventing the file from being deleted, even by super users. When you have verified the reason for this and still want to delete the file then remove the “i” attribute with:
chattr -i filename.ext
Then delete the file using rm as you normally would.
There can be several reasons for Let’s Encrypt certificates not being issued for sites. These are some things to check:
By default, the logged in client’s IP-address and hostname are not present in the outgoing email headers which makes it hard to trace the origin in case of abuse.
To make roundcube add this to the email headers of outgoing email, put this in the roundcube configuration file:
// put user's ip and host name in mail headers to enable trace
$config['http_received_header'] = true;
If awstats or webalizer is not containing any data and the client web logs are empty, the cause might be missing mounts of the log directories in /etc/fstab.
Search /etc/fstab for the client domain name. If no log mount is found, add a line for the client web site manually in this form:
/var/log/ispconfig/httpd/DOMAIN.COM /var/www/clients/clientNNN/webNNN/log none bind,nobootwait 0 0
After that do:
mount -a
mount
to verify it is mounted. After nightly cron, check that awstats or webalizer contains data.
The asterisk log file (/var/log/asterisk/full) shows entries like this:
[Sep 3 04:02:08] ERROR[3984] chan_sip.c: Serious Network Trouble; __sip_xmit returns error for pkt data
Solution: The server had been moved from one public IP-address to another. In Asterisk PBX settings, the fields for both External IP and Bind Address (under Advanced) needed adjustment to the new IP-address. After server reload everything worked normally.
After a system update I started to receive cron messages saying “/etc/cron.daily/amavisd-new:
Please run this cronjob as user amavis”.
It turns out that this happens because the cron script is replaced by a new one located in /etc/cron.d and the one in /etc/cron.daily is left behind giving this error message.
Solution: After checking that the new script exists in /etc/cron.d, just delete /etc/cron.daily/amavisd-new
If you are using mysql:secure_installation witch you should, beware of that the script reset all passwords in the SQL server database mysql. To fix this problem use the following.
Root password:
ALTER USER ‘root’@’localhost’ IDENTIFIED BY ‘MyNewPass’;
Session password:
ALTER USER ‘mysql.session’@’localhost’ IDENTIFIED BY ‘password’ PASSWORD EXPIRE NEVER;
Exampel error messages:
ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.