ss: Display Linux TCP / UDP Network and Socket Information

Posted on in Categories Debian Linux, Howto, Linux, Monitoring, Networking, RedHat/Fedora Linux, Sys admin, Tips, Troubleshooting, Ubuntu Linux last updated June 2, 2009

The ss command is used to show socket statistics. It can display stats for PACKET sockets, TCP sockets, UDP sockets, DCCP sockets, RAW sockets, Unix domain sockets, and more. It allows showing information similar to netstat command. It can display more TCP and state information than other tools. It is a new, incredibly useful and faster (as compare to netstat) tool for tracking TCP connections and sockets. SS can provide information about:

  • All TCP sockets.
  • All UDP sockets.
  • All established ssh / ftp / http / https connections.
  • All local processes connected to X server.
  • Filtering by state (such as connected, synchronized, SYN-RECV, SYN-SENT,TIME-WAIT), addresses and ports.
  • All the tcp sockets in state FIN-WAIT-1 and much more.

Lighttpd mod_rrdtool: Monitor The Load, Requests Per Seconds and Traffic

Posted on in Categories CentOS, Debian Linux, fedora linux, Hardware, Howto, lighttpd, Linux, Monitoring, RedHat/Fedora Linux, Ubuntu Linux last updated May 23, 2009

The round-robin database tool aims to handle time-series data like network bandwidth, temperatures, CPU load etc. The data gets stored in round-robin database so that system storage footprint remains constant over time. Lighttpd comes with mod_rrdtool to monitor the server load and other details. This is useful for debugging and tuning lighttpd / fastcgi server performance.

Red Hat / CentOS VSFTPD FTP Server Configuration

Posted on in Categories CentOS, FTP Server, Howto, Iptables, Linux, RedHat/Fedora Linux, Security, User Management last updated May 21, 2009

Vsftpd (Very Secure FTP Daemon) is an FTP server for UNIX-like systems, including CentOS / RHEL / Fedora and other Linux distributions. It supports IPv6, SSL, locking users to their home directories and many other advanced features.

In this guide you will learn:

  1. Setup vsftpd to provide FTP service.
  2. Configure vsftpd.
  3. Configure Firewalls to protect the FTP server.
  4. Configure vsftpd with SSL/TLS.
  5. Setup vsftpd as download only anonymous internet server.
  6. Setup vsftpd with virtual users and more.

Linux HugeTLBfs: Improve MySQL Database Application Performance

Posted on in Categories CentOS, Hardware, High performance computing, Howto, MySQL, RedHat/Fedora Linux last updated May 20, 2009

Applications that perform a lot of memory accesses (several GBs) may obtain performance improvements by using large pages due to reduced Translation Lookaside Buffer (TLB) misses. HugeTLBfs is memory management feature offered in Linux kernel, which is valuable for applications that use a large virtual address space. It is especially useful for database applications such as MySQL, Oracle and others. Other server software(s) that uses the prefork or similar (e.g. Apache web server) model will also benefit.

The CPU’s Translation Lookaside Buffer (TLB) is a small cache used for storing virtual-to-physical mapping information. By using the TLB, a translation can be performed without referencing the in-memory page table entry that maps the virtual address. However, to keep translations as fast as possible, the TLB is usually small. It is not uncommon for large memory applications to exceed the mapping capacity of the TLB. Users can use the huge page support in Linux kernel by either using the mmap system call or standard SYSv shared memory system calls (shmget, shmat).

How To: Print Labels in Ubuntu Linux

Posted on in Categories Gnome, Howto, Linux, Linux desktop, OpenOffice.Org last updated April 7, 2009

I haven’t had to use MS-Office / word in years and I have never had a problem with awesome OpenOffice.org software. I have been using it in Linux for a long time, and recently at work we started using it in windows-xp systems too. I have also got a couple other people in my school, work and small business to use it as well. This tutorial explains the approach you take when you want to print labels under Ubuntu Linux using gLabels. It is a label, business and media cover designer for the GNOME. The intuitive editor allows to create text fields, insert images, simple objects, and create barcodes. It is designed to work with common laser/inkjet printers peel-off label and business card sheets. From the article:

Ubuntu has no shortages of software for printing labels. Many users content themselves with the label and mail merge features in OpenOffice.org Writer or in Abiword or KOffice. All these solutions will do a basic job, especially with text. But what if you want elaborate formatting or graphics with your labels? What if you want a smaller, dedicated program that is quicker to load than a complete word processor? In these cases, you should consider turning to gLabels instead.

=> Printing Labels in Ubuntu

How To Use Gmail Account To Relay Email From a Shell Prompt

Posted on in Categories Backup, Debian Linux, fedora linux, Howto, Linux, Linux desktop, RedHat/Fedora Linux, Tip of the day last updated April 5, 2009

Usually, you do not need to setup an email server under Linux desktop operating system. Most GUI email clients (such as Thunderbird) supports Gmail POP3 and IMAP configurations. But, how do you send mail via the standard or /usr/bin/mail user agents or a shell script? Programs such as sendmail / postfix / exim can be configured as a gmail smarthost but they are largely overkill for this use.

Lighttpd Install mod_geoip For Country / City Level Geo Targeting

Posted on in Categories CentOS, Debian Linux, FreeBSD, Gentoo Linux, Howto, lighttpd, Linux, Networking, package management, RedHat/Fedora Linux, Suse Linux, Ubuntu Linux, UNIX last updated March 29, 2009

Geolocation software is used to get the geographic location of visitor using IP address. You can determine country, organization and guess visitors location. This is useful for:

a] Fraud detection.

b] Geo marketing and ad serving.

c] Target content.

d] Spam fighting.

e] And much more.

mod_geoip is a Lighttpd module for fast ip/location lookups. In this tutorial you will learn about mod_geoip installation and php server side examples to determine visitors country.

Missing Memory

Posted on in Categories Howto, Linux, RedHat/Fedora Linux, Sys admin, Troubleshooting, UNIX, Windows server last updated March 13, 2009

Today, I’ve upgraded total 8 servers from 4GiB to 8GiB to improve performance of system by inserting additional memory modules. We started each server and checked for memory count at console. All severs booted normally after the upgrade and services such as SMTP, NFS, CIFS, HTTP started as expected. Shortly, afterwords I got a call from help desk about pop3 server for slow performance.

Tips To Protect Linux Servers Physical Console Access

Posted on in Categories Debian Linux, Hardware, Howto, Kde, Linux, Linux desktop, Linux distribution, package management, RedHat/Fedora Linux, Sys admin, Tips, Ubuntu Linux last updated March 12, 2009

This is an user contributed article.

Linux computer console is a physical device to operate a computer / server. Here are few steps which, if taken, make it more difficult for an attacker to quickly modify a system from its console.

Dealing with Recession – Saving Money With Free and Open Source Software

Posted on in Categories Debian Linux, Howto, Linux, Linux desktop, News, RedHat/Fedora Linux, Ubuntu Linux last updated March 2, 2009

According to wikipedia – “An economy which grows over a period of time tends to slow down the growth as a part of the normal economic cycle. An economy typically expands for 6-10 years and tends to go into a recession for about six months to 2 years”. The current defaults on homeloan have led to a major crisis in the US. Once recession started consumers lose confidence in the growth of the economy and spend less including technology and software. Is free and open source software (FOSS) a way to cut business costs? As concern about recession – even depression – deepens, more and more companies are asking this question. However, many have trouble knowing how to begin to find an answer.