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

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 June 8, 2017

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 required? How big should your Linux / UNIX swap space be?

Linux / UNIX: Find Out If a Directory Exists or Not

in Categories CentOS, Debian Linux, File system, Gentoo Linux, Howto, Linux, Open source coding, programming, RedHat/Fedora Linux, Shell scripting, Suse Linux, Sys admin, Ubuntu Linux, UNIX last updated November 16, 2008

I’ve already written a small tutorial about finding out if a file exists or not under Linux / UNIX bash shell. However, couple of our regular readers like to know more about a directory checking using if and test shell command.

Download Of The Day: GIMP 2.6 For Linux / Windows / Mac OS X

in Categories Debian Linux, Download of the day, Gentoo Linux, Gnome, GNU/Open source, Linux, Linux desktop, OS X, Ubuntu Linux, UNIX, windows vista last updated October 1, 2008

GIMP version 2.6 has been released and available for download. It is a free raster graphics editor used to manipulate digital graphics and photographs under Linux and other operating systems. It is often used as a free software replacement for Adobe Photoshop, the most widely used bitmap editor.

Linux / UNIX: Geany Lightweight Integrated Development Environment

in Categories C Programming, CentOS, Debian Linux, Gentoo Linux, Gnome, Linux desktop, Open source coding, RedHat/Fedora Linux last updated July 9, 2008

Geany is cross platform (UNIX/Windows/BSD) fast, powerful, easy to use integrated development environment for PHP, Java, C and much more. If you wanted to quickly edit source code, Geany is for you. Here’s an introduction to using Geany’s built-in features, including the IDE and built-in development capabilities.

Linux Configure Netconsole To Log Messages Over UDP Network

in Categories CentOS, Debian Linux, File system, FreeBSD, Gentoo Linux, GNU/Open source, Hardware, kernel, Linux, Linux distribution, Linux Log Management, Security, Sys admin, Tips, Troubleshooting, Ubuntu Linux last updated July 2, 2008

Linux netconsole kernel module allows dmesg output to be transmitted via the syslogd network. It is kernel-level network logging over udp allowing debugging of problem where disk logging fails and serial consoles are impractical. This is a step-by-step mini howto about netconsole configuration under Red Hat, CentOS, Fedora and Debian Linux.

Get Information about All Running Services Remotely

in Categories Debian Linux, FreeBSD, Gentoo Linux, Hardware, Howto, Linux last updated January 29, 2008

From my mailbag the other day I received an interesting suggestion about obtaining information regarding all running process and network connections remotely using inetd / xinetd :

SSH client can be used to execute a command(s) on a remote UNIX box. Same technique can be used to get current network and system information using netstat information:
ssh you@remotebox netstat -a
ssh you@remotebox netstat -tulpn

He suggests that above command can be run via inetd / xinetd so that admin can connect easily and get information using telnet from 100s UNIX boxes. All you have to do is open /etc/inetd.conf under UNIX / Linux:
# vi /etc/inetd.conf
Append following line:
netstat stream tcp nowait root /bin/netstat netstat -a
Restart inetd:
# /etc/init.d/openbsd-inetd restart
Next, use telnet to connect to the netstat service (port 15) and get network connection information:
$ telnet server-name netstat
$ telnet 192.168.1.5 15

Output:

Trying 192.168.1.5...
Connected to 192.168.1.5.
Escape character is '^]'.
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 *:6881                  *:*                     LISTEN
tcp        0      0 *:6081                  *:*                     LISTEN
tcp        0      0 *:nfs                   *:*                     LISTEN
tcp        0      0 localhost:6082          *:*                     LISTEN
tcp        0      0 *:54053                 *:*                     LISTEN
tcp        0      0 *:59275                 *:*                     LISTEN
tcp        0      0 *:netstat               *:*                     LISTEN
tcp        0      0 *:sunrpc                *:*                     LISTEN
tcp        0      0 localhost:webcache      *:*                     LISTEN
tcp        0      0 *:43218                 *:*                     LISTEN
tcp        0      0 *:domain                *:*                     LISTEN
tcp        0      0 localhost:ipp           *:*                     LISTEN
tcp        0      0 *:telnet                *:*                     LISTEN
tcp        0      0 *:3128                  *:*                     LISTEN
tcp        0      0 localhost:smtp          *:*                     LISTEN
tcp        0      1 vivek-desktop.loc:48925 bas4-kitchener06-:56662 SYN_SENT
tcp        0      0 vivek-desktop.loc:54791 customer5673.pool:16273 ESTABLISHED
tcp        0      0 vivek-desktop.loc:38398 59.94.1xx.yy:45483      ESTABLISHED
tcp        0      0 vivek-desktop.loc:42048 60.21.zz.yyy:23235       ESTABLISHED
...........
....
....
unix  3      [ ]         STREAM     CONNECTED     15973
unix  3      [ ]         STREAM     CONNECTED     15947    /var/run/dbus/system_bus_socket
unix  3      [ ]         STREAM     CONNECTED     15946
unix  3      [ ]         STREAM     CONNECTED     15936    /var/run/dbus/system_bus_socket
unix  3      [ ]         STREAM     CONNECTED     15935
unix  2      [ ]         DGRAM                    15931
unix  3      [ ]         STREAM     CONNECTED     15916
unix  3      [ ]         STREAM     CONNECTED     15915
unix  2      [ ]         DGRAM                    15906
Connection closed by foreign host.

There are few problems with this solution:
a] Unnecessary service running at port # 15

b] Telnet protocol is not secure

c] I strongly recommend using ssh and password-less login for scripts to obtain this kind of information:
ssh user@remote-box netstat -a
ssh user@remote-box df -H
ssh user@remote-box free -m
ssh user@remote-box /path/to/script.pl

Deluge: Ultimate Linux / UNIX / Mac / Windows GUI Bittorrent Client ( bt Client )

in Categories CentOS, Debian Linux, Download of the day, Gentoo Linux, GNU/Open source, Linux, Linux desktop, OS X, Ubuntu Linux, UNIX, Windows last updated January 13, 2008
deluge-logo.png

A long time ago I wrote about Linux command line bittorrent client. Recently I switched from command line client to a GUI based client called Deluge.

Deluge is a lightweight, open source free software and cross-platform BitTorrent client (bt client). A Bittorrent client written in Python/PyGTK which offers following benefits:

[a] Full Encryption – To avoid ISP’s bandwidth throttling system (note encryption is not here to protect you from other users)

[b] Plugin System – Just like Firefox it has features rich plugin collection; in fact, most of Deluge’s functionality is available in the form of plugins.

[c] In built RSS support to grab latest and greatest stuff.

[d] Global and per bittorrent bandwidth control.

[e] Support for selective file downloading – For example, it allows to grab a single file from 100 of files

[f] Ability to create torrent with Torrent Creator plugin

[g] Proxy support

[h] Network activity graph

[i] Network Health Monitor

[j] And much more

Quick Deluge Installation

Use apt-get command,
$ sudo apt-get install deluge-torrent
You can start Deluge by visiting Application > Internet > Deluge Bittorrent Client
Linux / MAC / WIndows / UNIX - Deluge Bittorrent client written in Python/PyGTK
(Fig. 01: Deluge Bittorent Client in Action)

Change port settings

The official ports for BitTorrent are 6881-6889, but most ISPs block or at least throttle those ports, so I recommend to use a port range of something between 50000 and 65535 or any other random range. You can change port range from Preference > Select Network tab > Setup new range > Close
Change port settings
(Fig. 02: Change Port Settings [ Image Credit Official Project])

Download Deluge Bittorrent Client

=> Visit Official Deluge Bittorrent Client project web site to grab latest version.