sudo aptitude install pdftk
(if you run Fedora, RedHat or CentOS use this one: sudo yum install pdftk)

Split large pdf into many one-page files:

pdftk largepdfile.pdf burst

(as the result you will get many small files like pg_0001.pdf, pg_0002.pdf and so on).

Merge files into one PDF file:

pdftk *.pdf cat output onelargepdfile.pdf

pdftk is extremely powerful and makes it possible to do almost anything with input pdf files. Thus above two commands are just examples showing how to split and merge pdf files in Ubuntu easily.

Anyways sometimes Packet Tracer as like as dynamips/gns3 are not a panacea when it’s necessary to emulate mid-sized network or test some specific ios features on real Cisco devices. There are several options: the first and the easiest one means to buy Cisco device. But we all know that Cisco’s pricing policy is far away from democratic in application to individual users so even used or refurbished Cisco router/switch will cost enough to think about another option. Second option is to schedule access to Community Lab at packetlife.net. Nice to know the access to it is absolutely free so anyone can get logon to Cisco routers, switches or ASAs once user reached his/her timeslot. Here is the list of hardware you can have access to (there are multiple devices of the same model):

Cisco ASA 5505
Cisco 2811 (2xWIC-2T)
Cisco 1841 (1xWIC-2T)
Cisco Catalyst 3550-24

Not bad for free lab as for me. The lab is broken into two blocks so user can reserve only one block or both blocks simultaneously. This is to make it possible to access the lab by multiple users simultaneously. Devices are connected to each other according to predefined topology — see separate diagrams for Ethernet and Serial connections below (they are split to prevent overhead on the graph I guess). All documentation as well as FAQs can be found here: here and here. Thanks to Jeremy Stretch.

P.S. By the way if you can share any other similar labs allowing people on the web to access Cisco (or some other networking devices) — you are welcome to share this information here. Thanks!

Today it came to my mind that it is time to make sensitive information stored on my usb flash drive encrypted but still transportable and easy to use. But I don’t want to have whole my 32 GB usb drive fully encrypted using truecrypt or something similar. It is just toooo slow. I also don’t want to use GPG for uncompressing files and directories every time I would like to read them and then create new GPG compressed file every time I save changes. This eats too much of my time and system resources. At the same time it is necessary to be able to use that usb drive under windows, mac, linux whatever (read/write files) but still have my directory structure with sensitive files encrypted. Here is the solution: create encrypted filesystem within a file named, say, 16GB.candy.bin that could be stored on regular windows formatted usb flash drive and then mounted under Linux using the password.

When it becomes necessary I can mount that 16GB.candy.bin as the regular ext3 filesystem with all those stuff like permissions, ownership etc. that is available on ext3 but not in FAT or NTFS. On my windows formatted flash drive candy takes only 16 GB so I can use the rest of space to store not so sensitive information like mp3, movies or photos. Moreover I on windows or linux to read it.

Let’s create that 16GB.candy.bin file with encrypted ext3 filesystem (read below explanations below carefully before just to copy/paste commands into CLI):

[root@artemn root]# cd /path/to/candy/

[root@artemn root]# tune2fs -i 0 -c 0 /dev/loop0

Here are some points: using above commands we create encrypted file of 16 GB so if you need to have more or less just change “count=16000″ in dd line. “count=16000″ means 16GB so “count=20″ means 20MB. Path ‘/path/to/candy/’ is for example only so you should change it to real directory that is able to host encrypted file (16 GB in above example). Command losetup is present in most Linux distributions (btw I recommend Ubuntu especially newly released Lucid Lynx) but if it is not use your disro’s packet manager to install it or compile from sources (for super geeks only, Mr. Stallman if you read this article — Hello). Reader, you can replace “/dev/urandom” in dd line with “/dev/zero” that will make that command to finish faster but will lower security level of resulting file (read about AES for better understanding). You will need to enter the password when running losetup command so make sure it safe and long enough like ‘6U2sAsR37Hn8122dGsaPrew1twt’ but not ‘abc123′ or ‘iloveyou’.

Once commands are done you will get 16GB.candy.bin containing encrypted ext3 filesystem. You can store this file where ever you want, say, on a flash drive. If you loose it nobody won’t be able to open it until he (or she!) cracked AES encryption (use long passwords to prevent this). As the next step it is required to mount filesystem and store some files/directories in it:

[root@artemn root]# mkdir -p /mnt/candy

[root@artemn root]# umount /mnt/candy

When you unmount 16GB.candy.bin the changes are already saved there so it’s not required to compress and encrypt anything unlike with GPG.

P.S. This post is inspired by Loopback tricks article. Thanks to the author. Good luck!

Text editors like gedit, emacs, nano or vi will certainly live forever but thankfully there are numerous visual html editors for my Ubuntu They are sometimes called WYSIWYG editors, it mean “What You See Is What You Get”.

1. Quanta Plus

This is KDE/Qt visual html editor available as binary package for numerous Linux distributions
including Debian and Ubuntu. From developers’ site:

Quanta Plus is a highly stable and feature rich web development environment.
The vision with Quanta has always been to start with the best architectural
foundations, design for efficient and natural use and enable maximal user
extensibility.

In order to install it in Debian/Ubuntu run the following CLI command:

sudo apt-get install quanta

Fedora, Centos, Redhat users type this:

sudo yum install kdewebdev

I found Quanta html editor extremely useful, this is just an outstanding application of this
field.

2. Bluefish

Bluefish is a powerful editor targeted towards programmers and webdesigners,
with many options to write websites, scripts and programming code. Bluefish
supports many programming and markup languages, and it focuses on editing
dynamic and interactive websites.

I found this really versatile html editor. Besides HTML/CSS it handles C,
Java, Perl, Python, XML and others.

Ubuntu and Debian users type:

sudo apt-get install bluefish

Fedora/Redhat/Centos:

sudo yum install bluefish

Gentoo:

emerge bluefish

3. Screem

SCREEM is a web development environment. It’s purpose is to increase
productivity when constructing a site, by providing quick access to commonly
used features. While it is written for use with the GNOME desktop environment
in mind it does not specifically require you to be running it, just have the
libraries installed.

This is one of the most user-friendly Gnome HTML editor. Its simple interface
brings extremely powerfull HTML editor so if like minimalistic design Screem
is your choice.

Update: below is the bottom line from Linux.com’s review of three Linux HTML editors (Quanta Plus, Blowfish,
Screem). I found that review after I wrote this post.

• If you use GNOME, use Screem. It’s a fast, simple, and powerful tool for web editing. However, it does not have the large feature sets that Bluefish and Quanta Plus have, especially for languages other than those directly related to Web page editing.
• If you use GNOME and need the more powerful features of Quanta Plus, load the required libraries and run it.
• If you use KDE and want a code editor, choose Quanta Plus. Ignore the WYSIWYG capabilities and take advantage of the tremendous editing capabilities, especially for CSS style sheets.
• If you use Xfce, Quanta Plus should run fine. Screem would still require loading additional libraries.
• Finally, if you use GNOME, find that Screem does not meet all your needs, and you don’t want to bother with loading the KDE-native Quanta Plus, then load Bluefish. It is nearly as capable as Quanta Plus, but will run well without a lot of fussing with libraries.

artemn@artemn-laptop:~$ cat /etc/passwd | awk '{print length, $0}' | sort -n | awk '{$1=""; print $0 }'

bin:x:2:2:bin:/bin:/bin/sh
sys:x:3:3:sys:/dev:/bin/sh
root:x:0:0:root:/root:/bin/bash
proxy:x:13:13:proxy:/bin:/bin/sh
mail:x:8:8:mail:/var/mail:/bin/sh
lp:x:7:7:lp:/var/spool/lpd:/bin/sh
sync:x:4:65534:sync:/bin:/bin/sync
ntp:x:110:120::/home/ntp:/bin/false
daemon:x:1:1:daemon:/usr/sbin:/bin/sh
ftp:x:111:65534::/home/ftp:/bin/false
games:x:5:60:games:/usr/games:/bin/sh
klog:x:102:103::/home/klog:/bin/false
man:x:6:12:man:/var/cache/man:/bin/sh
irc:x:39:39:ircd:/var/run/ircd:/bin/sh
dhcp:x:100:101::/nonexistent:/bin/false
news:x:9:9:news:/var/spool/news:/bin/sh
saned:x:120:131::/home/saned:/bin/false
syslog:x:101:102::/home/syslog:/bin/false
uucp:x:10:10:uucp:/var/spool/uucp:/bin/sh
backup:x:34:34:backup:/var/backups:/bin/sh
www-data:x:33:33:www-data:/var/www:/bin/sh
libuuid:x:112:121::/var/lib/libuuid:/bin/sh
messagebus:x:103:109::/var/run/dbus:/bin/false
nobody:x:65534:65534:nobody:/nonexistent:/bin/sh
sshd:x:109:65534::/var/run/sshd:/usr/sbin/nologin
Debian-exim:x:117:128::/var/spool/exim4:/bin/false
artemn:x:1000:1000:artemn,,,:/home/artemn:/bin/bash
list:x:38:38:Mailing List Manager:/var/list:/bin/sh
mysql:x:119:130:MySQL Server,,,:/var/lib/mysql:/bin/false
gdm:x:108:118:Gnome Display Manager:/var/lib/gdm:/bin/false
hplip:x:104:7:HPLIP system user,,,:/var/run/hplip:/bin/false
pulse:x:113:123:PulseAudio daemon,,,:/var/run/pulse:/bin/false
polkituser:x:114:127:PolicyKit,,,:/var/run/PolicyKit:/bin/false
avahi:x:106:114:Avahi mDNS daemon,,,:/var/run/avahi-daemon:/bin/false
asterisk:x:118:129:Asterisk PBX daemon,,,:/var/lib/asterisk:/bin/false
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/bin/sh
haldaemon:x:107:116:Hardware abstraction layer,,,:/home/haldaemon:/bin/false
landscape:x:115:65534:Landscape Client Daemon,,,:/var/lib/landscape:/bin/false
avahi-autoipd:x:105:113:Avahi autoip daemon,,,:/var/lib/avahi-autoipd:/bin/false
chipcard:x:116:119:Chipcard-Tools Daemon Account,,,:/var/run/chipcard:/bin/false

For reverse sort, use the following command:

cat /etc/passwd | awk '{print length, $0}' | sort -rn | awk '{$1=""; print $0 }'

Source: www.opennet.ru

Imagine the following situation: you have to compile some Linux/Unix application or kernel module that requires kernel source present at your hard drive, say, in /usr/src/kernels/kernel-2.6.21-i386/ or elsewhere. But there is not enough disk space to copy these sources or install kernel-devel or linux-source packages (in Fedora/RedHat or Ubuntu/Debian distros respectively)… Sounds familiar? Believe me, sometimes it happens

As a solution you can mount the directory of some remote PC that contains needed kernel source. It can be done via several protocols like smb, ftp etc. In this article we will mount remote directory using ssh protocol that is one the most popular for remote and secure access to Linux boxes over the network.

Below are the steps which should be taken to get the ball rolling. We need two packages: sshfs and fuse-utils.

1. Install necessary packages:

a. Ubuntu/Debian:

sudo aptitude install fuse-utils sshfs

b. Fedora/Centos/RedHat:

yum install fuse-sshfs fuse fuse-libs

c. Other Linux: download and compile sshfs/fuse from sources

2. Check that kernel module fuse is loaded:

lsmod | grep fuse

There should be the line containing “fuse” in the output (of not try modprobe fuse).

3. Mount remote filesystem using something like this (two commands):

mkdir -p /mnt/sshfs/
sshfs remote-user@remote-machine:/some/directory /mnt/sshfs

where remote-user is the username allowed to login remote-machine via ssh protocol. It will ask you to type the password so just type it and press return

4. That’s it. Good luck!

What is .docx actually? It’s Microsoft’s file format representing word processor documents and named OpenXML (as an attempt to create open and free international standard). Today .docx is default format for Microsoft’s word processor Word.

There are myriads of online converters between OpenXML and OpenOffice formats including .docx, .xlsx, .odt and many etc but sometimes it’s much more better to just open received .docx file in Linux offline (if there is temporarily no Internet connection or for security/private reasons etc).

So, just download the following package to certain directory like /usr/src, here are the commands to do it:

1. cd /usr/src
2. sudo wget http://blog.mypapit.net/imej/odf_filter.tar.bz2

The next step is to unpack the contents of the archive (.tar.bz2 is definitely well compressed file) and copy 3 files to OpenOffice’s system directories:

3. sudo tar -xvjf odf_filter.tar.bz2
4. sudo cp OdfConverter /usr/lib/openoffice/program/
5. sudo cp MOOXTypeDetection.xcu /usr/lib/openoffice/share/registry/modules/org/openoffice/TypeDetection/Types/
6. sudo cp MOOXFilter_cpp.xcu /usr/lib/openoffice/share/registry/modules/org/openoffice/TypeDetection/Filter/

As you can see from picture below now it’s possible to natively open .docx files in openoffice under Linux. Of course such “native” support may imply some artefacts in opened files due to file formats incompatibility so it’s also a good option to ask your friends to convert .docs into .pdf before sending you

P.S. Thanks to guys from mypapit.

P.S. Here are several online converters .doc(x) <-> .odf <-> .pdf:

1. ZAMZAR (possibly the best converter), 2. http://docx-converter.com/.

1. mplayer (sudo aptitude install mplayer)
2. lame (sudo aptitude install lame)
3. win32 codecs (sudo aptitude install ubuntu-restricted-extras)

and then convert file.wma into file.mp3 using the following console command:

mplayer -vo null -vc dummy -af resample=44100 -ao pcm:waveheader file.wma;lame -m s -V 3 audiodump.wav;mv audiodump.wav.mp3 file.mp3;rm audiodump.wav

This also works for Fedora / Centos / Redhat family Linux distributions (requirements should be installed by yum package manager via third-party software repositories).

ethtool

This is rather powerful utility can display and change settings of ethernet network interface card. You can easily disable/enable autonegotiation option for your NIC, also it’s possible to manually set up duplex mode, configure wake-on-lan options, set speed settings. Just look through full manual page for ethtool. Here are several ethtool usage examples:

ethtool eth0 – shows current NIC settings

Settings for eth0:
        Supported ports: [ TP MII ]
        Supported link modes:   10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
        Supports auto-negotiation: Yes
        Advertised link modes:  10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
        Advertised auto-negotiation: No
        Speed: 10Mb/s
        Duplex: Half
        Port: MII
        PHYAD: 32
        Transceiver: internal
        Auto-negotiation: off
        Supports Wake-on: pumbg
        Wake-on: d
        Current message level: 0x00000007 (7)
        Link detected: yes

ethtool -s eth0 duplex half autoneg off – disables auto-negotiation, enables Half Duplex.
ethtool -s eth1 duplex full speed 1000 autoneg off – disables auto-negotiation, enables Falf Duplex and sets up Speed to 1000 Mb/s.

mii-tool

According to manual it allows to manipulate and see media-independent interface status. Let’s see examples:

bash-3.1# mii-tool eth0
eth0: negotiated 100baseTx-FD, link ok – shows 100 Mbps speed, Full Duplex, Auto-negotiation is on.
bash-3.1# mii-tool eth0 -F 10baseT-HD – enables 10 Mb/s Half Duplex connection.

Well, after quick testings there are no doubts that it is not a good option if you wish to have quick and stable alternative for Firefox… But of course it is good for evaluation purposes or for those people who CAN’T wait for official release of Chrome for Linux Certainly the port is based on Windows copy run by Wine (don’t forget to upgrade it). Actually CodeWeavers says that this is just a proof of concept, for fun, and to showcase what Wine can do.