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 September 1, 2014

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.

Howto Upgrade Debian 4 Etch to Debian 5.0 Lenny

Posted on in Categories Debian Linux, GNU/Open source, Howto, Linux, Linux desktop, Linux distribution, Security, Troubleshooting last updated February 16, 2009

Debian version 5.0 has been released. It is recommended that you upgrade the system to latest version. Upgrading remote Debian server is a piece of cake. In this tutorial, you will learn about upgrading Debian Linux server from Etch to Lenny over ssh session.

FreeBSD 7.2RC Released

Posted on in Categories FreeBSD, Hardware, Howto, Networking, News last updated April 25, 2009

The second of two planned Release Candidates for the FreeBSD 7.2-RELEASE cycle is now available. ISO images for Tier-1 architectures are now available on most of the FreeBSD mirror sites.

The freebsd-update(8) utility supports binary upgrades of i386 and amd64
systems running earlier FreeBSD releases. Systems running 7.0-RELEASE,
7.1-RELEASE, 7.2-BETA1, or 7.2-RC1 can upgrade as follows:

# freebsd-update upgrade -r 7.2-RC2

During this process, FreeBSD Update may ask the user to help by merging
some configuration files or by confirming that the automatically performed
merging was done correctly.

# freebsd-update install

The system must be rebooted with the newly installed kernel before continuing.
# shutdown -r now

After rebooting, freebsd-update needs to be run again to install the new
userland components, and the system needs to be rebooted again:

# freebsd-update install
# shutdown -r now

Linux: Should You Use Twice the Amount of Ram as Swap Space?

Posted on in Categories data center, Debian Linux, fedora linux, File system, FreeBSD, Gentoo Linux, kernel, Linux, Linux desktop, Linux laptop, OpenBSD, RedHat/Fedora Linux, Solaris, Storage, Suse Linux, Tuning, Ubuntu Linux, UNIX last updated December 8, 2008

Linux and other Unix-like operating systems use the term “swap” to describe both the act of moving memory pages between RAM and disk, and the region of a disk the pages are stored on. It is common to use a whole partition of a hard disk for swapping. However, with the 2.6 Linux kernel, swap files are just as fast as swap partitions. Now, many admins (both Windows and Linux/UNIX) follow an old rule of thumb that your swap partition should be twice the size of your main system RAM. Let us say I’ve 32GB RAM, should I set swap space to 64 GB? Is 64 GB of swap space really required? How big should your Linux / UNIX swap space be?

Troubleshooting Lighttpd Chrooted RedHat PHP Version 5.1.6-20.el5_2.1

Posted on in Categories CentOS, GNU/Open source, kernel, lighttpd, Linux, Linux distribution, php, RedHat/Fedora Linux, Troubleshooting last updated October 1, 2008

It appears that latest php version 5.1.6-20.el5_2.1 under RHEL / CentOS Linux v5.2 has made some major changes. As a result choort jail setup using previous instructions no longer works. PHP is crashing with segmentation fault errors. So I had to trace php errors using strace command.