The “mail for domain.com loops back to myself” error occurs when a mail server is configured to accept email for a domain it is responsible for but is unable to deliver it to the correct recipient. This usually happens because the DNS MX record for the domain points to the server itself. To fix this … Read more

When running the BIND (Berkeley Internet Name Domain) DNS server on a Linux or Unix-based system, you may encounter the following error message: max open files (1024) is smaller than max sockets (4096) This error message indicates that the maximum number of open files allowed by the system is less than the maximum number of … Read more

Upgrading from FreeBSD 7.x to 7.2 Stable Release involves performing a source upgrade. Here are the steps to upgrade from FreeBSD 7.x to 7.2: Before starting the upgrade process, it is recommended to back up important data and configurations. This will help you recover in case anything goes wrong during the upgrade process. Update the … Read more

The zlib-devel RPM package contains the development libraries and header files for the zlib library. These files are required to compile programs that use the zlib library. Here’s how to install the zlib-devel RPM package on CentOS: Open a terminal window on your CentOS system. Install the yum-utils package if it is not already installed. … Read more

The “SPAMHAUS BLOCKLIST ADDRESS IS WRONG MUST FIX” error usually occurs when there is an incorrect or outdated IP address in the Spamhaus blocklist configuration file. This can cause legitimate email messages to be blocked by the email server. Here’s how to fix the issue: Edit the Spamhaus blocklist configuration file. The file is typically … Read more

Tunneling an X connection through an intermediate Linux/BSD gateway involves forwarding X11 protocol packets over SSH connections, so that the display of the remote X application can be displayed on the local X server. Here are the steps to set up tunneling of X connections: Connect to the intermediate gateway using SSH: $ ssh gateway.example.com … Read more

In FreeBSD, it is possible to move the /usr or /var file systems to another hard disk. The steps below will guide you through the process: Backup the contents of the /usr or /var file system to the new hard disk. You can use rsync for this purpose: sudo rsync -avz /usr /mnt/new_disk In the … Read more

To allow ping and traceroute commands inside a FreeBSD jail, you will need to modify the jail’s configuration to allow ICMP traffic. Edit the jail’s configuration file: sudo vi /etc/jail.conf Add the following line to the configuration file, replacing jail_name with the name of your jail: exec.start += “sh /etc/rc.initial.jail_name” This line will execute the … Read more

To install and configure mod_security on Red Hat or CentOS, you can follow these steps: Install the mod_security package using yum: sudo yum install mod_security After installation, the mod_security module is enabled by default. You can edit the mod_security.conf file to customize its configuration, if needed: sudo vi /etc/httpd/conf.d/mod_security.conf This file contains various directives that … Read more

To gracefully restart the Lighttpd web server, you can use the lighttpd command with the -s option and the graceful-restart argument. Here’s the command you can use: sudo lighttpd -s graceful-restart When you run this command, Lighttpd will reload its configuration and gracefully restart the server. This means that any active connections will be allowed … Read more