system
How to Monitor Network Services with TCP Wrappers in Linux
Most Linux distributions ship with tcp_wrappers “wrapping” all your TCP services. A tcp_wrapper (known as /usr/sbin/tcpd) is invoked from/sbin/inetd instead of the real service, such as telnet or ftp. tcpd then checks the host that is requesting the service and either executes the real server or denies access from that host. tcpd allows you to restrict access to your tcp services. You should make [...]
How to Bypass a Forgotten Root Password
It’s never happened to me, but I’m sure it’s happened to others. The root password is gone. Forgotten. Changed maliciously. Mysteriously gone. The Linux Gazette has a great article on the three most common ways to deal with this situation. It’s important to note that there’s no way to actually recover the password, but you can change [...]
How to do a System Audit for your Linux box
Unfortunately, there is no such things as a standard Linux installation. The wide variety of servers available, coupled with each particular distribution’s installation options, make providing a ready made list impossible. The best that can be done is show you how to list all running services, and point you in the right general direction. Now [...]
What Is PHP-Nuke
It is a CMS (Content Managment System) that integrates in its inside all the instruments that are used to create a site/portal of information (meant in broad sense). Given the immense number of present functions in the installation and in an even greater quantity of modules developed from third parties, the system is also adept to the management of
How to have e-mail delivered at special times
E-Mail delivery can be invoked by issuing the command “sendmail -q”. For those who are interested in what sendmail actually does, “sendmail -q -v” will give a more verbose version of the delivery process.
It is very convenient to automate the process of e-mail delivery. A tool commonly used for this process is cron.
How to Connect and Disconnect from MySQL Server
To connect to the server, you will usually need to provide a MySQL user name when you invoke mysql and, most likely, a password. If the server runs on a machine other than the one where you log in, you will also need to specify a host name. Contact your administrator to find out what connection parameters [...]
How to Speed Your File System Up By 40% – Linux
Every time a file is read from your Linux ext3 partition it writes back a attribute to the file detailing the last access time. There are very few programs that actually use this to operate and it slows everything down. Disabling atime and diratime on your Linux ext3 file systems can improve disk performance up [...]
How to do a Simple Network Performance Test – Linux
FTP on Linux and other Unix systems allows you to pass shell commands to the ftp client by using the pipe symbol ‘|’ as the first character of the file name. With this feature you can send a very large file to a remote host using /dev/zero as input and /dev/null as output.
How yo Patch Linux Systems
Building an infrastructure for patch management is another very important step to proactively secure Linux production environments. It is recommended to have a written security policy and procedure to handle Linux security updates and issues. For example, a security policy should detail the timeframe for assessment, testing, and rollout of patches. Network related security vulnerabilities [...]
How to Monitor File Systems in Red Hat Linux
Red Hat Linux provides a utility called diskcheck that monitors the amount of free disk space on the system. Based on the configuration file, it will send email to the system administrator when one or more disk drives reach a specified capacity. To use this utility, you must have the diskcheck RPM package installed. This utility is run as [...]
How to find Memory Usage in Red Hat Linux
The free command displays the total amount of physical memory and swap space for the system as well as the amount of memory that is used, free, shared, in kernel buffers, and cached.
How to Configure a DHCP Server – FreeBSD system
Unlike the built-in dhclient, your FreeBSD system does not come with DHCP server software. This is because you only need to configure a DHCP server if you want to lease out IP configuration for your own network. However, there are two ports that allow you to create your own DHCP server. The first is known [...]