Yesteday with Baky (my dear Orthodox Coptic Christian friend) and Kliment (a good friend from the old rock’n’roll years), we went to the Dobrich Cinema (sadly just one cinema for the city is available). The cinema in Dobrich is called Cinema Club Icarus (Ikar). For all foreigners who wants to enjoy some movie, the Dobrich Cinema does offer a plenty of English speaking movies (with Bulgarian subtitles).
Pitily the Dobrich Cinema website http://www.kinoikar.com/bg/info/2 is not existing in English, though anyone wanting to check the current projected movies in the cinema can use the movie trailers and the movie pictures to get the necessery info.
Anyways I haven’t been to a cinema for some almost two months, so going for a movie was really relaxing enjoyable experience. Besides that, we were lucky to see a movie which fitted quite well to my movie genre preferences –
Midnight in Paris
. Midnight in Paris is a Romantic Comedy for intellectuals and people who have a glipmse on art. Its a Bohemian movie so to say and I believe it wouldn’t hold a big interest for the avarage man who doesn’t keep interest in Arts, History or Philosophy.
The movie plot revives around a young engaged American couple who went to Paris for a business trip, just to find out there whole life is gonna be changed by this. The main actor Gil a just grown man is writting a Novel book, trying to make a shift of his profession from being a movie directory to a novel publicist. Gil (Owen Wilson) is an odd Bohemian kind of man, who quickly fells in love with Paris rich culture architecture and old fame. Next to that Gil is a dreamer who (just like me dreams about the old glorious times), when people were more respectable better moral and more idealistic than in the current age. After one night of heavy wine drinking, Gil’s fiancee wents for some dancing and leaves him on his own. Gil makes a round in Paris and losts himself and decides to stay for a while in front of sold old Roman Catholic Cathedral, a mysterious very old car crosses by the street and suddenly some “party” gang asks Gil to join. He has no idea where he is going and suddeny finds himself in the epoch of the world famous 1920 of great book publicists like the Fidgeralds family. Night by night Gil is being transferred to a different epoch back in time to meet a world famous artists and authors, people like Ernest Hemingway, Picaso, Salvador Dali etc. etc. 😉
The movie shows many personages of odd world famous people with some of their strangeties known by the current age. It appears all of them are dreaming for all and the same thing, to live in a earlier age to live in the Golden Age of Arts and Poetry 😉
The movie is real fun in Gil’s personage I’ve seen a lot of “me”, also I’ve seen a lot of me in many of the other famous people as of course presented in the movie. I hardly recommend this movie to anyone who wants to take a break, have a good mindful laugh time. Here is Midnight in Paris movie trailer as well to get an idea what to expect:
I have few servers, which have automatically enabled IPv6 protocols (IPv6 gets automatically enabled on Debian), as well as on most latest Linux distribituions nowdays.
Disabling IPv6 network protocol on Linux if not used has 2 reasons:
1. Security (It’s well known security practice to disable anything not used on a server) Besides that IPv6 has been known for few criticil security vulnerabilities, which has historically affected the Linux kernel. 2. Performance (Sometimes disabling IPv6 could have positive impact on IPv4 especially on heavy traffic network servers). I’ve red people claiming disabling IPv6 improves the DNS performance, however since this is not rumors and did not check it personally I cannot positively confirm this.
Disabling IPv6 on all GNU / Linuces can be achieved by changing the kernel sysctl settings net.ipv6.conf.all.disable_ipv6 by default net.ipv6.conf.all.disable_ipv6 equals 1 which means IPv6 is enabled, hence to disable IPv6 I issued:
server:~# sysctl net.ipv6.conf.all.disable_ipv6=0
To set it permanently on system boot I put the setting also in /etc/sysctl.conf :
The aforedescribed methods should be working on most Linux kernels version > 2.6.27 in that number it should work 100% on recent versions of Fedora, CentOS, Debian and Ubuntu.
To disable IPv6 protocol on Debian Lenny its necessery to blackist the ipv6 module in /etc/modprobe.d/blacklist by issuing:
On Fedora / CentOS there is a another universal “Redhat” way disable IPv6.
On them disabling IPv6 is done by editting /etc/sysconfig/network and adding:
NETWORKING_IPV6=no
IPV6INIT=no
I would be happy to hear how people achieved disabling the IPv6, since on earlier and (various by distro) Linuxes the way to disable the IPv6 is probably different.
Alto to stop Iptables IPV6 on CentOS / Fedora and RHEL issue:
While reading some log files on one of the co-located servers at UK2.net , I’ve noticed dmesg log was filling in with tons of junk messages like:
[4288245.609762] IPv6 addrconf: prefix with wrong length 48
[4288445.984153] IPv6 addrconf: prefix with wrong length 48
[4288646.296110] IPv6 addrconf: prefix with wrong length 48
[4288846.609119] IPv6 addrconf: prefix with wrong length 48
[4289046.922604] IPv6 addrconf: prefix with wrong length 48
[4289247.267273] IPv6 addrconf: prefix with wrong length 48
[4289447.545800] IPv6 addrconf: prefix with wrong length 48
[4289647.857789] IPv6 addrconf: prefix with wrong length 48
[4289848.169308] IPv6 addrconf: prefix with wrong length 48
[4290048.595104] IPv6 addrconf: prefix with wrong length 48
[4290248.808497] IPv6 addrconf: prefix with wrong length 48
[4290449.103503] IPv6 addrconf: prefix with wrong length 48
[4290649.418747] IPv6 addrconf: prefix with wrong length 48
[4290849.742731] IPv6 addrconf: prefix with wrong length 48
After checking the message to make sure it would not suddeny lead to server hang ups I figured out the message is not dangerous but just an annoying warning that some other (routing) host on the same network as mine is advertising something using IPv6, that doesn’t fit with my IPv6 server config. Actually the server doesn’t use the IPv6 configuration at all, and the assigned configuration is just some kind of auto set IPv6 IP address. The server, where this message appeared is powered by 64 bit Debian GNU / Linux Squeeze
To resolve the annoying message, 5 of the kernel sysctl settings needs to be modified with cmds:
Furthermore to prevent the IPv6 addrconf: prefix with wrong length 48 to re-appear after future server reboots / boots the two sysctl values of course needs to be included in /etc/sysctl.conf e.g.:
My server has 2 etherhet interfaces, eth0 and eth1 that’s the reason I had to set up autoconf kernel the two vars net.ipv6.conf.eth0.autoconf and net.ipv6.conf.eth1.autoconf , for more interfaces more kernel vars (eth2, eth3) etc. needs to be set to “0”
I’ve seen posts online of people complaining about a similar errors to IPv6 addrconf: prefix with wrong length 48, like:
IPv6 addrconf: prefix with wrong length 96 IPv6 addrconf: prefix with wrong length 128
The solution to this messages is also done by setting the above described sysctl kernel vars. Setting the vars will suppress the messages which by the way with time could take up A LOT of disk space and fills /var/log/dmesg with this useless message, hence applying the “fix” is a must 😉
Another thing, I’ve noticed while I was researching about the error and the respective fix is that people on other deb based distributions like Ubuntu as well as on Fedora GNU / Linux had also experienced the issue.
The usual way that one is supposed to check a certain partition let’s say /dev/sda1 disk UUID (Universal Unique Identifier) label is through a command: vol_id /dev/sda1
For reason however Debian does not include vol_id command. To check the UUID assigned disk labels on Debian one should use another command called blkid (part of util-linux deb package).
blkid will list all block device attributes so it doesn’t specifically, passing any partition as argument. Here is an example output of blkid :
I’m realizing the more I’m converting to a fully functional GUI user, the less I’m doing coding or any interesting stuff… I remembered of the old glorious times, when I was full time console user and got a memory on a nifty trick I was so used to back in the day. Back then I was quite often writing shell scripts which were fetching (html) webpages and converting the html content into a plain TEXT (TXT) files
In order to fetch a page back in the days I used lynx – (a very simple UNIX text browser, which by the way lacks support for any CSS or Javascipt) in combination with html2text – (an advanced HTML-to-text converter).
Let’s say I wanted to fetch a my personal home page https://www.pc-freak.net/, I did that via the command:
The content from www.pc-freak.net got spit by lynx as an html source and passed html2pdf wchich saves it in plain text file pcfreak_page.txt The bit more advanced elinks – (lynx-like alternative character mode WWW browser) provides better support for HTML and even some CSS and Javascript so to properly save the content of many pages in plain html file its better to use it instead of lynx, the way to produce .txt using elinks files is identical, e.g.:
By the way back in the days I was used more to links , than the superior elinks , nowdays I have both of the text browsers installed and testing to fetch an html like in the upper example and pipe to html2text produced garbaged output.
Here is the time to tell its not even necessery to have a text browser installed in order to fetch a webpage and convert it to a plain text TXT!. wget file downloading tools supports source dump as well, for all those who did not (yet) tried it and want to test it:
$ wget -qO- https://www.pc-freak.net | html2text
Anyways of course, some pages convertion of text inside HTML tags would not properly get saved with neither lynx or elinks cause some texts might be embedded in some elinks or lynx unsupported CSS or JavaScript. In those cases the GUI browser is useful. You can use any browser like Firefox, Epiphany or Opera ‘s File -> Save As (Text Files) embedded functionality, below is a screenshot showing an html page which I’m about to save as a plain Text File in Mozilla Firefox:
Besides being handy in conjunction with text browsers, html2text is also handy for converting .html pages already existing on the computer’s hard drive to a plain (.TXT) text format. One might wonder, why would ever one would like to do that?? Well I personally prefer reading plain text documents instead of htmls 😉 Converting an html files already existing on hard drive with html2text is done with cmd:
$ html2text index.html >index.txt
To convert a whole directory full of .html (documentation) or whatever files to plain text .TXT , cd the directory with HTMLs and issue the one liner bash loop command:
$ cd html/
html$ for i in $(echo *.html); do html2text $i > $(echo $i | sed -e 's#.html#.txt#g'); done
Now lay off your back and enjoy reading the dox like in the good old hacker days when .TXT files were fashionable 😉
I decided to start this post with this picture I found on onlamp.com article called “Simplify Your Life with Apache VirtualHosts .I put it here because I thing it illustrates quite well Apache’s webserver internal processes. The picture gives also a good clue when Virtual Hosts gets loaded, anways I’ll go back to the main topic of this article, hoping the above picture gives some more insight on how Apache works.; Here is how to list all the enabled virtualhosts in Apache on Debian GNU / Linux serving pages:
server:~# /usr/sbin/ apache2ctl -S
VirtualHost configuration:
wildcard NameVirtualHosts and _default_ servers:
*:* is a NameVirtualHost
default server exampleserver1.com (/etc/apache2/sites-enabled/000-default:2)
port * namevhost exampleserver2.com (/etc/apache2/sites-enabled/000-default
port * namevhost exampleserver3.com (/etc/apache2/sites-enabled/exampleserver3.com:1)
port * namevhost exampleserver4.com (/etc/apache2/sites-enabled/exampleserver4.com:1)
...
Syntax OK
The line *:* is a NameVirtualHost, means the Apache VirtualHosts module will be able to use Virtualhosts listening on any IP address (configured on the host), on any port configured for the respective Virtualhost to listen on.
The next output line: port * namevhost exampleserver2.com (/etc/apache2/sites-enabled/000-default
Shows requests to the domain on any port will be accepted (port *) by the webserver as well as indicates the <VirtualHost> in the file /etc/apache2/sites-enabled/000-default:2 is defined on line 2 (e.g. :2).
To see the same all enabled VirtualHosts on FreeBSD the command to be issued is:
freebsd# pcfreak# /usr/local/sbin/httpd -S VirtualHost configuration:
wildcard NameVirtualHosts and _default_ servers:
*:80 is a NameVirtualHost
default server www.pc-freak.net (/usr/local/etc/apache2/httpd.conf:1218)
port 80 namevhost www.pc-freak.net (/usr/local/etc/apache2/httpd.conf:1218)
port 80 namevhost pcfreak.afraid.org (/usr/local/etc/apache2/httpd.conf:1353)
...
Syntax OK
On Fedora and the other Redhat Linux distributions, the apache2ctl -S should be displaying the enabled Virtualhosts.
One might wonder, what might be the reason for someone to want to check the VirtualHosts which are loaded by the Apache server, since this could be also checked if one reviews Apache / Apache2’s config file. Well the main advantage is that checking directly into the file might sometimes take more time, especially if the file contains thousands of similar named virtual host domains. Another time using the -S option is better would be if some enabled VirtualHost in a config file seems to not be accessible. Checking directly if Apache has properly loaded the VirtualHost directives ensures, there is no problem with loading the VirtualHost. Another scenario is if there are multiple Apache config files / installs located on the system and you’re unsure which one to check for the exact list of Virtual domains loaded.
GNU / Linux and FreeBSD had a nifty little program (tool) called dhcping . dhcping – send a DHCP request to DHCP server to see if it’s up and running. dhcping is also able to send a request to DHCP servers on a whole network range and therefore it can e asily be used as a scanner to find any available DHCP servers in a network. This makes dhcping a nmap like scanner capable to determine if dhcp servers are in a network 😉 To scan an an entire network range with dhclient and find any existing DHCP servers:
noah:~# dhcping -s 255.255.255.255 -r -v
Got answer from: 192.168.2.1
received from 192.168.2.1, expected from 255.255.255.255
no answer
In above’s output actually my Dlink wireless router returns answer to the broadcast DHCP LEASE UDP network requests of dhcping . On a networks where there is no DHCP server available, the requests dhcping -s 255.255.255.255 -r -v returns:
noah:~# dhcping -s 255.255.255.255 -r -v
no answer
This article was inspired by a post, I’ve red by a friend (Amridikon), so thx goes to him.
I’ve playing trying to learn InkScape – The Open Source vector graphic editor .By so far I’m quite impressed on how easy this program is learned and how easy graphical manipulation with this nifty program can be done. The default format in which InkScape saves its files is SVG (Scalable Vectors Graphics). For all those unfamiliar with SVG – SVG is an open (free format) format developed in 1999 which insetad of containing binary data like PNG or JPEG does contain plain XML content. SVG being consisted of plain XML has multiple advantageous, the most important one makes it easy for text and visual data to be displayed among different program svg readers in absolutely identical way. Besides that the format if read with plain text editor like vim or emacs can be altered directly via the source. Being multi system interoperable makes SVG as a great format for text and visual data storage in HTML5, actually SVG is already a part of the HTML5 html coding standard. And most probably its adoption rate will raise up drastically as soon as HTML5 starts substitute HTML4 and lower web standards.
Anyways I’m slipping away from the aim of this post so I’ll stop blabbering on how great SVG is and let people check it out for themselves (if not already).
Going back to the aim of my article to show How to convert SVG to PNG graphical extension on GNU / Linux and FreeBSD
After producing a bunch of files with InkScape I realized the default format in which Inkscape stores its files is SVG , this was okay with me but since I wanted to have my experimental produced content in PNG I needed a way to convert SVG to My first logical guess was that The Gimp will be able to handle the situation and after opening my SVG file with GIMP and used the gimp File -> Save As option and give the SVGfile an extension of PNG , Gimp succesfully converted the file to PNG.
However I wanted to dig further and check out what is the standard accepted way to convert SVG files using a plain command. This will possibly be handy to me if I had to do something online (let’s say a website) which will accept SVG and will require the SVG files to be converted and also stored in PNG or other Graphic file formats.
After checking online, I’ve found a post which pointed me to librsvg2 which contains RSVG – (Turn SVG files into raster images.)
librsvg is available as a package in most mainstream Linux distributions nowdays, Fedora, Debian etc., as well as contains a port inside the FreeBSD ports system. Since I’m using Debian on my notebook where I installed and tested the command line SVG to PNG convertion the way I did it is:
noah:/home/hipo/Desktop# apt-get --yes install librsvg2-bin
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
librsvg2-bin
0 upgraded, 1 newly installed, 0 to remove and 16 not upgraded.
Need to get 72.5 kB of archives.
After this operation, 180 kB of additional disk space will be used.
Get:1 http://ftp.nl.debian.org/debian/ squeeze/main librsvg2-bin amd64 2.26.3-1 [72.5 kB]
Fetched 72.5 kB in 0s (184 kB/s)
Selecting previously deselected package librsvg2-bin.
(Reading database ... 376046 files and directories currently installed.)
Unpacking librsvg2-bin (from .../librsvg2-bin_2.26.3-1_amd64.deb) ...
Processing triggers for man-db ...
Setting up librsvg2-bin (2.26.3-1) ...
Afterwards the exact convertion of my Inscape SVG file drawing.svg to drawing.png using rsvg I’ve done like so:
hipo@noah:~/Desktop$ rsvg drawing.svg drawing.png
The convertion results for me was 100% uniqueness between the file converted and the output PNG. Some people might wonder why I didn’t used Inkscape’s Export to Bitmap function and then use convert command part of ImageMagick in order to convert the produced Inkscape bitmap to PNG.
One other thing worthy to mention is on Debian, librsvg2-bin contains 2 more executable besides rsvg. One is the rsvg-view command which allows one to view SVG files using command line or Graphic enviroment, the other one is rsvg-convert which supports again SVG convertion to PDF and to PNG
Before proceeding with the other described ways to convert SVG to PNG earlier in this article, I give a try to Inkscape’s Export to Bitmap embedded function but the produced bitmap did not resembled the original SVG file so I decided to completely abandon this method Maybe there is some particular reason of the chaotic way I’ve tested Inkscape to place random images sometimes going out of the field of a paper etc. which influenced the improper generation of Bitmap using Inkscape, despite that it seems InkScape needs some more development until the bugs in Bitmap producing get fixed and it can be freely used to produce Bitmaps.
Maybe there is some particular reason for the failure of Inkscape to produce a good BMP file, like for example the chaotic way I’ve tested Inkscape to place random images sometimes going out of the field of a paper borders etc.This should have influenced the improper generation of Bitmap using Inkscape, anyhow it seems InkScape needs some more development until the bugs in Bitmap creation get fixed.
By the way if you’re wondering how to convert PNG to bitmap BMP after, once having converted SVG to PNG this is easily doable with convert command, like so:
Maybe in future releases it will be a good idea if InkScape developers integrate a convertion to other formats this will make it handy and make surely these nice program more popular among users. Hope this is helpful. Cheers and as RMS likes to say Happy Hacking 😉
Even though, I rarely use Windows to connect to remote servers using SSH or Telnet protocols in some cases I’m forced to do that (in cases I’m away from my Linux notebook). I’m doing my best to keep away from logging anywhere via SSH using Windows as when using Windows you never know what kind of spyware, malware or Viruses is already on the system, not to mention Microsoft are sniffing a lot if not everything which is typed on the keyboard… Anyways, usually I use Putty as a quick way to access a remote SSH, however pitily PuTTY lacks an embedded functionality for Tabs and each new connection to a server I had to run a new instance of PuTTY. This is okay if you need to access a single server but in some cases where access to multple servers is necessery lacking the tab functionality and starting 10 times putty is really irritating and one forgets what kind of connection is present on which PuTTY instance.
Earlier on, I’ve blogged about the existence of PuTTY Connection Manager PuTTY add-on program which is a PuTTY wrapper which enables PuTTY to be used with Connection Tabs feature, however installing two programs is quite inconvenient, especially if you have to do this every few days (in case if travelling a lot).
Luckily there is another terminal emulator free program for Windows called PodeRoSA which natively supports a tabbed Secure Shell connections. If you want to get some experience with it check out Poderosa’s website , here is also a screenshot of the program running few ssh encrypted connections in tabs on a Windows host.
Another good reason that one might consider using Poderosa instead of PuTTY is the Apache License under which Poderosa is developed. Currently the Apache License is compatible with GPL free software license which makes the program fully free software. The PuTTY license is under BSD and MIT and some other weird custom license not 100% compatible with GPL and hence PuTTY can be considered less free software in terms of freedom.
I’m currently reading Free as in Freedom (2.0) R. Stallman and the Free Software Revolution The book includes a reference to Eric S. Raymond ‘s famous The Cathedral and the Bazaar which does makes a point about the important of Open Source . I’ve read the The Cathedral and the Bazaar paper some very long time ago (in my young days so to say) and hence I couldn’t resemble much of the document so I jumped in after the footnote in the FAIF book and decided to take a quick look on The Cathedral and the Bazaar once again to bring up some memories. I was stunned to find the paper is available in many formats but officially not included in PDF . Since i’m a GNU / Linux user I’ve never managed to get into the habit to read postscript documents which from modern day stand point are also already a bit of obsolete and therefore I found it as a wise idea to convert and mirror the POSTSCRIPT (PS) version of the document to PDF on www.pc-freak.net
Happily the ps2pdf command to convert the ps to pdf on my debian gnu / linux is really easy:
Even though the “open source” movement is an interesting idea and it had some major impact on the development of some free software the idiology of open source which was very much influenced by this document is very weak compared to the philosophy Richard Stallman indcuded as of the great need of the software to be free.
To be honest looking back in time for a long time being a Linux user I did not make any distinguishment between “Free Software” concept and “Open Source”, even worser I considered to evangelize on Open Source not realizing that initially what attracted me to free software was the idiology of open source and not the real values on which ground free software is built. This kind of miss understanding between perception of “open source” and “free software” I got and spread for years now I fully realize and I seem like when I red back then The Cathedral and the Bazaar document I didn’t looked any critical at the document but it had a major, I would say “bad” impact on my idiology on software for a long time. So for all those who had not checked it it’s worthy checking but only in case if one fully understands Richard Stallman’s concept of Free Software, without this understanding one can easily slip into the wrong believe (just like me back in thme) that open source is the same as free software. Even though open source can be free software it is not presumably that an open source is free software and that it guarantees that the published source will be free. But I’ll stop now as I slept away from my goal of the article to just log here how a convertion of postscript to pdf on gnu / linux is done. Just to close up this article I warmly recommend on all people interested into hacking and the history of Free operating systems and Free software as FreeBSD and GNU / Linux the Free as in Freedom (2.0) book ! Its truly a remarkable and great inspirational reading for all people like me involved into free software realm of ICT.
And shall not uncircumcision which is by nature, if it fulfil the law, judge thee, who by the letter and circumcision dost transgress the law? -- Romans 2:27
