server

What is nagios? Nagios is a utility designed to monitor network services such as HTTP, SMTP, POP3, HTTP, ICMP, NNTP, monitor CPU usage, disk space and other hardware. Also, nagios can send you alerts in case of any problems with the above services or hardware. Install nagios on CentOS To...

What is Fail2ban Fail2ban protects the server from password brute force and SSH hacking and also able to protect certain partitions on a server running Apache or NGINX. Installing Fail2ban on CentOS # Get the Epel repository: sudo yum install epel-release # Install fail2ban yum install...

301 redirect A 301 redirect is a permanent redirect from one page to another. Most often, webmasters use it when transferring a page to a new address, changing a domain name, or creating site mirrors. Setting up a redirect via HTML and PHP Simple redirect: <meta http-equiv="refresh"...

Basic dns settings for mail server Name Type Value Additional domain.com. A (internet address v4) 90.190.100.0 mail.domain.com. A (internet address v4) 90.190.100.0 imap.domain.com. A (internet address v4) 90.190.100.0 www.domain.com. A (internet address v4) 90.190.100.0...

What is a DKIM signature? The DKIM signature is used to authenticate the sender's email address. DKIM key generation First of all, you need to generate a pair of DKIM keys, public and private. Public key example: -----BEGIN PUBLIC KEY-----...

What is X Frame Option header? The X-Frame-Options HTTP header is used to guide the browser which pages of the site can be displayed in <frame> , <iframe> , and <embed> . This technology does not allow loading website's content in frames on third-party resources, thereby protecting it from...

What is strict Transport Security header Strict Transport Security (HSTS) is a header that guides the browser never load a site via HTTP protocol. This technology allows you to protect the user from attacks by hackers. With the correct HSTS configuration, even during the first load of the site...

What is Permissions Policy header? HTTP Permissions-Policy security header specifies which browser features can and cannot be used. This can help to improve the privacy and security of the website, like turning off the camera and microphone. Can also be used to enforce guidelines (such as...

What is header - Referrer-Policy The HTTP Referrer-Policy header report to the browser how much information the browser should process during the web page processing. This technology is used to protect the security and privacy of the user. Basic directives no-referrer - do not send information...

Adding new SMTP user After installing PowerMTA manually, you will need to create a new SMTP user and virtual-mta. To create an user, edit the virtualhost.txt file: # Adding new VMTA-user <smtp-user user1> # user's name password password XXXXX # user's password...

SMTP port in pmta config To change the SMTP port in PMTA, find and edit the config file at /etc/pmta/config Find the line that starts with smtp-listener This line specifies the port used by the PMTA server. If you need to use several ports, duplicate the line. smtp-listener 0/0:2424...

CLI commands for PMTA server System PowerMTA reboot service pmta restart Reloading the pmta config pmta reload Reload pmtahttp pmtahttp restart Launching PowerMTA service pmta start Search for possible errors pmtad --debug Reset statistics pmta reset counters Checking the status of PMTA...

What is the main configuration file of PMTA This is a file which is located in the etc/pmta/ directory of your server and responsible for the rules of sending mail from a particular domain/ip address. Two files are responsible for the configuration of your mail server, config and...

Protect website via htaccess This list for .htaccess contains more than 1900 bad bots, grabbers, spammers, combiners and other garbage. Blocking them will help to reduce the load on your site, which will positively affect it's performance and security. At the same time, search engines bots...

Set up own VPN with using OpenVPN client software You will need a server with bandwidth 200 Mbps and pre-installed Ubuntu 20.04 or later. 1. Connect to your server: ssh root@ip 2. Install git: apt install git 3. Install OpenVPN: git clone https://github.com/Nyr/openvpn-install.git cd...

List of dangerous functions exec() - calling an external program proc_open() - executes a command and opens a file pointer for I/O shell_exec() - executes a command in a shell and returns the full output as a string system() - calling an external program and displaying the result passthru() -...