Posts Tagged ‘linux os’

Linphone a good working Skype voice over IP alternative

Monday, February 4th, 2013

If you never tried linphone I warmly recommend it.
2 days ago, with a friend of mine we tested a bunch of Linux softwares to find out what is the situation with possible alternatives to Skype to transmit Voice and Video. I've been interested into Skype Alternative programs since about 2 years, but so far I never found good and easy to set up working Linux alternative.

We first tried Ekiga. Though it is said to be a good Linux SKype alternative, my ekiga client running on Debian Linux stable Squeeze ver. 3.2.7.2 failed to connect to SIP account I've created on ekiga.net. I've tried hard to make ekiga connect to account SIP created from ekiga.net but all time I was getting an error on connect:

Ekiga did not manage to configure your network settings automatically. You can still use it, but you need to configure your network settings manually.

Please see http://wiki.ekiga.org/index.php/Enable_port_forwarding_manually for instructions

ekiga cant login to SIP protocol error enable port forwarding manually - ekiga is not ready to use on Linux

After continously trying to follow instructions from above pointed URL and making proper settings on my DL-524 Wireless Router and all time ending up with the annoying error, we decided to finally completely abondoned it and try some other voice over IP clients.
We  tried Jitsi and few others which prooved to be unworking. Finally we give a try to Linphone which seemed to be promising. We tested it On Linux platform, where both of Linux installed OS-es where tested were running Debian Linux (one stable Debian Squeeze and one unstable Debian Blackstar). Linphone even with different versions on different Debian Linux OS-es worked fine Video conferences were crashing but voice over IP via SIP protocol works okay.

Setting up linphone to do speak (voice over IP) conference calls with friends is easy task, you need to have linphone package installed, i.e. run:

apt-get install –yes linphone

Then once installed launch it from terminal or GNOME menus with:

$ linphone-3

You will have to create account on linphone.org's website via Register a Linphone account. Once registered and confirmed the account, linphone sends you an email with credential info, through e-mail like:
 

Dear Linphone user, your account has been activated.

You can now use your linphone account with these parameters :

sip:hipo@sip.linphone.org
hipo
sip.linphone.org
 

Regards,
The Linphone team.

Then in linphone you should configure new created Linphone account via:

Linphone -> Preferences -> Manager SIP Account

LinPhone Working Linux Skype Alternative Settings Screenshot
 

Once account is added, calls via SIP protocol are ready to go. Probabl,y due to incompitability between versions of Debian stable Linux and unstable the user you will add and about to call is showing as offline, however calling between each other works perfect and voice quality is quite good.

good working skype  inux alternative to proprietary skype voice video chat program - linphone rulez

Linphone has a version for Windows as well as for AppleIphone mobile phone.

LinPhone for Iphone version dialpad picture

For console geeks, there is also a command line tool interface to linphone linbphonec;

$ linphonec
Warning: Could not start UDP transport on port 5060, maybe this port is already used.
Ready
Warning: video is disabled in linphonec, use -V or -C or -D to enable.
linphonec>
linphonec> help
Commands are:
---------------------------
help Print commands help
call Call a SIP uri
chat Chat with a SIP uri
terminate Terminate the current call
answer Answer a call
autoanswer Show/set auto-answer mode
proxy Manage proxies
soundcard Manage soundcards
webcam Manage webcams
staticpic Manage static pictures when nowebcam
ipv6 Use IPV6
refer Refer the current call to the specified destination.
nat Set nat address
stun Set stun server address
firewall Set firewall policy
call-logs Calls history
friend Manage friends
play play from a wav file
record record to a wav file
quit Exit linphonec
register Register in one line to a proxy
unregister Unregister from default proxy
duration Print duration in seconds of the last call.
status Print various status information
ports Network ports configuration
speak Speak a sentence using espeak TTS engine
codec Audio codec configuration
vcodec Video codec configuration
ec Echo cancellation
mute Mute microphone and suspend voice transmission.
unmute Unmute microphone and resume voice
transmission.
nortp-on-a Set the rtp_no_xmit_on_audio_mute
configuration parameter
---------------------------
Type 'help ' for more details.
linphonec> quit

Another great thing about Linphone is it is licensed under free software license GPL2 – meaning source is publicly accessible – thus anyone with skills and desire to port it to any computer architecture can do it. I did not have time to test it throughfully with newer version of linphone to know if Video calls works fine – whether same program versions are used between both peer sides, nevertheless for anyone willing non M$ sniffed channel to do voice calls between Computers linphone is nice.

 

 

 

 

 

 

How to add support for DJVU file format on M$ Windows, Mac, GNU / Linux and FreeBSD

Thursday, June 14th, 2012

Windjview Format paper Clipper logo / support DjView on Windows and Linux

By default there is no way to see what is inside a DJVU formatted document on both Windows and Linux OS platforms. It was just a few months ago I saw on one computer I had to fix up the DJVU format. DJVU format was developed for storing primary scanned documents which is rich in text and drawings.
Many old and ancient documents for example Church books in latin and some older stuff is only to be found online in DJVU format.
The main advantage of DJVU over lets say PDF which is also good for storing text and visual data is that DJVU's data encoding makes the files much more smaller in size, while still the quality of the scanned document is well readable for human eye.

DJVU is a file format alternative to PDF which we all know has been set itself to be one of the major standard formats for distributing electronic documents.

Besides old books there are plenty of old magazines, rare reports, tech reports newspapers from 1st and 2nd World War etc in DJVU.
A typical DJVU document takes a size of only lets say 50 to 100 KBytes of size just for comparison most a typical PDF encoded document is approximately sized 500 KiloBytes.

1.% Reading DJVU's on M$ Windoze and Mac-s (WinDjView)

The program reader for DJVU files in Windows is WinDjView WinDjView official download site is here

WinDjView is licensed under GPLv2 is a free software licensed under GPL2.

WinDjView works fine on all popular Windows versions (7, Vista, 2003, XP, 2000, ME, 98, NT4).

WinDjView with opened old document Sol manual ,,,,

I've made a mirror copy of WinDjView for download here (just in case something happens with the present release and someone needs it in future).

For Mac users there is also a port of WinDjView called MacDjView ;;;,

2.% Reading DJVU files on GNU / Linux

The library capable of rendering DJVUs in both Linux and Windows is djviewlibre again free software (A small note to make here is WinDjView also uses djviewlibre to render DJVU file content).

The program that is capable of viewing DJVU files in Linux is called djview4 I have so far tested it only with Debian GNU / Linux.

To add support to a desktop Debian GNU / Linux rel. (6.0.2) Squeeze, had to install following debs ;;;

debian:~# apt-get install --yes djview4 djvulibre-bin djviewlibre-desktop libdjviewlibre-text pdf2djvu
........
...

pdf2djvu is not really necessery to install but I installed it since I think it is a good idea to have a PDF to DJVU converter on the system in case I somedays need it ;;;

djview4 is based on KDE's QT library, so unfortunately users like me who use GNOME for a desktop environment will have the QT library installed as a requirement of above apt-get ;;;

Here is Djview4 screenshot with one opened old times Bulgarian magazine called Computer – for you

DJVU Pravetz Computer for you old school Bulgarian Pravetz magazine

Though the magazine opens fine, every now and then I got some spit errors whether scrolling the pages, but it could be due to improperly encoded DJVU file and not due to the reader. Pitily, whether I tried to maximize the PDF and read it in fullscreen I got (segfault) error and the program failed. Anyways at least I can read the magazine in non-fullscreen mode ;;; ,,,,

3.% Reading DJVU's on FreeBSD and (other BSDs)

Desktop FreeBSD users and other BSD OS enthusiasts could also use djview4 to view DJVUs as there is a BSD port in the ports tree.
To use it on BSD I had to install port /usr/ports/graphics/djview4:

freebsd# cd /usr/ports/graphics/djview4
freebsd# make install clean
,,,,...

For G / Linux users who has to do stuff with DJVU files, there are two other programs which might be useful:
 

  • a) djvusmooth – graphical editor for DjVu
  • b) gscan2pdf – A GUI to produce PDFs or DjVus from scanned documents

DJVUSmooth Debian GNU / Linux opened prog

I tried djusmooth to edit the same PDF magazine which I prior opened but I got an Unhandled exception: IOError, as you can in below shot:

DJVUSmooth Unhandled Exception IOError

This is probably normal since djvusmooth is in its very early stage of development – current version is 0.2.7-1

Unfortunately I don't have a scanner at home so I can't test if gscan2pdf produces proper DJVUs from scans, anyways I installed it to at least check the program interface which on a first glimpse looks simplistic:

gscan2pdf 0.9.31 Debian Linux Squeeze screenshot
To sum it up obviously DJVU seems like a great alternative to PDF, however its support for Free Software OSes is still lacking behind.
The Current windows DJVU works way better, though hopefully this will change soon.

FreeBSD Jumbo Frames network configuration short how to

Wednesday, March 14th, 2012

FreeBSD Jumbo Frames Howto configure FreeBSD

Recently I wrote a post on how to enable Jumbo Frames on GNU / Linux , therefore I thought it will be useful to write how Jumbo Frames network boost can be achieved on FreeBSD too.

I will skip the details of what is Jumbo Frames, as in the previous article I have thoroughfully explained. Just in short to remind you what is Jumbo Frames and why you might need it? – it is a way to increase network MTU transfer frames from the MTU 1500 to MTU of 9000 bytes

It is interesting to mention that according to specifications, the maximum Jumbo Frames MTU possible for assignment are of MTU=16128
Just like on Linux to be able to take advantage of the bigger Jumbo Frames increase in network thoroughput, you need to have a gigabyt NIC card/s on the router / server.

1. Increasing MTU to 9000 to enable Jumbo Frames "manually"

Just like on Linux, the network tool to use is ifconfig. For those who don't know ifconfig on Linux is part of the net-tools package and rewritten from scratch especially for GNU / Linux OS, whether BSD's ifconfig is based on source code taken from 4.2BSD UNIX

As you know, network interface naming on FreeBSD is different, as there is no strict naming like on Linux (eth0, eth1, eth2), rather the interfaces are named after the name of the NIC card vendor for instance (Intel(R) PRO/1000 NIC is em0), RealTek is rl0 etc.

To set Jumbro Frames Maximum Transmission Units of 9000 on FreeBSD host with a Realtek and Intel gigabyt ethernet cards use:freebsd# /sbin/ifconfig em0 192.168.1.2 mtu 9000
freebsd# /sbin/ifconfig rl0 192.168.2.2 mtu 9000

!! Be very cautious here, as if you're connected to the system remotely over ssh you might loose connection to it because of broken routing.

To prevent routing loss problems, if you're executing the above two commands remotely, you better run them in GNU screen session:

freebsd# screen
freebsd# /sbin/ifconfig em0 192.168.1.2 mtu 9000; /sbin/ifconfig rl0 192.168.1.2 mtu 9000; \
/etc/rc.d/netif restart; /etc/rc.d/routed restart

2. Check MTU settings are set to 9000

If everything is fine the commands will return empty output, to check further the MTU is properly set to 9000 issue:

freebsd# /sbin/ifconfig -a|grep -i em0em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9000freebsd# /sbin/ifconfig -a|grep -i rl0
rl0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 9000

3. Reset routing for default gateway

If you have some kind of routing assigned for em0 and rl0, network interfaces they will be affected by the MTU change and the routing will be gone. To reset the routing to the previously properly assigned routing, you have to restart the BSD init script taking care for assigning routing on system boot time:

freebsd# /etc/rc.d/routing restart
default 192.168.1.1 done
add net default: gateway 192.168.1.1
Additional routing options: IP gateway=YES.

4. Change MTU settings for NIC card with route command

There is also a way to assign higher MTU without "breaking" the working routing, e.g. avoiding network downtime with bsd route command:

freebsd# grep -i defaultrouter /etc/rc.conf
defaultrouter="192.168.1.1"
freebsd# /sbin/route change 192.168.1.1 -mtu 9000
change host 192.168.1.1

5. Finding the new MTU NIC settings on the FreeBSD host

freebsd# /sbin/route -n get 192.168.1.1
route to: 192.168.1.1
destination: 192.168.1.1
interface: em0
flags: <UP,HOST,DONE,LLINFO,WASCLONED>
recvpipe sendpipe ssthresh rtt,msec rttvar hopcount mtu expire
0 0 0 0 0 0 9000 1009

6. Set Jumbo Frames to load automatically on system load

To make the increased MTU to 9000 for Jumbo Frames support permanent on a FreeBSD system the /etc/rc.conf file is used:

The variable for em0 and rl0 NICs are ifconfig_em0 and ifconfig_rl0.
The lines to place in /etc/rc.conf should be similar to:

ifconfig_em0="inet 192.168.1.1 netmask 255.255.255.0 media 1000baseTX mediaopt half-duplex mtu 9000"
ifconfig_em0="inet 192.168.1.1 netmask 255.255.255.0 media 1000baseTX mediaopt half-duplex mtu 9000"

Change in the above lines the gateway address 192.168.1.1 and the netmask 255.255.255.0 to yours corresponding gw and netmask.
Also in the above example you see the half-duplex ifconfig option is set insetad of full-duplex in order to prevent some duplex mismatches. A full-duplex could be used instead, if you're completely sure on the other side of the host is configured to support full-duplex connections. Otherwise if you try to set full-duplex with other side set to half-duplex or auto-duplex a duplex mismatch will occur. If this happens insetad of taking the advantage of the Increase Jumbo Frames MTU the network connection could become slower than originally with standard ethernet MTU of 1500. One other bad side if you end up with duplex-mismatch could be a high number of loss packets and degraded thoroughout …

7. Setting Jumbo Frames for interfaces assigning dynamic IP via DHCP

If you need to assign an MTU of 9000 for a gigabyt network interfaces, which are receiving its TCP/IP network configuration over DHCP server.
First, tell em0 and rl0 network interfaces to dynamically assign IP addresses via DHCP proto by adding in /etc/rc.conf:

ifconfig_em0="DHCP"
ifconfig_rl0="DHCP"

Secondly make two files /etc/start_if.em0 and /etc/start_if.rl0 and include in each file:

ifconfig em0 media 1000baseTX mediaopt full-duplex mtu 9000
ifconfig rl0 media 1000baseTX mediaopt full-duplex mtu 9000

Copy / paste in root console:

echo 'ifconfig em0 media 1000baseTX mediaopt full-duplex mtu 9000' >> /etc/start_if.em0
echo 'ifconfig rl0 media 1000baseTX mediaopt full-duplex mtu 9000' >> /etc/start_if.rl0

Finally, to load the new MTU for both interfaces, reload the IPs with the increased MTUs:

freebsd# /etc/rc.d/routing restart
default 192.168.1.1 done
add net default: gateway 192.168.1.1

8. Testing if Jumbo Frames is working correctly

To test if an MTU packs are transferred correctly through the network you can use ping or tcpdumpa.) Testing Jumbo Frames enabled packet transfers with tcpdump

freebsd# tcpdump -vvn | grep -i 'length 9000'

You should get output like:

16:40:07.432370 IP (tos 0x0, ttl 50, id 63903, offset 0, flags [DF], proto TCP (6), length 9000) 192.168.1.2.80 > 192.168.1.1.60213: . 85825:87285(1460) ack 668 win 14343
16:40:07.432588 IP (tos 0x0, ttl 50, id 63904, offset 0, flags [DF], proto TCP (6), length 9000) 192.168.1.2.80 > 192.168.1.1.60213: . 87285:88745(1460) ack 668 win 14343
16:40:07.433091 IP (tos 0x0, ttl 50, id 63905, offset 0, flags [DF], proto TCP (6), length 9000) 192.168.1.2.80 > 192.168.1.1.60213: . 23153:24613(1460) ack 668 win 14343
16:40:07.568388 IP (tos 0x0, ttl 50, id 63907, offset 0, flags [DF], proto TCP (6), length 9000) 192.168.1.2.80 > 192.168.1.1.60213: . 88745:90205(1460) ack 668 win 14343
16:40:07.568636 IP (tos 0x0, ttl 50, id 63908, offset 0, flags [DF], proto TCP (6), length 9000) 192.168.1.2.80 > 192.168.1.1.60213: . 90205:91665(1460) ack 668 win 14343
16:40:07.569012 IP (tos 0x0, ttl 50, id 63909, offset 0, flags [DF], proto TCP (6), length 9000) 192.168.1.2.80 > 192.168.1.1.60213: . 91665:93125(1460) ack 668 win 14343
16:40:07.569888 IP (tos 0x0, ttl 50, id 63910, offset 0, flags [DF], proto TCP (6), length 9000) 192.168.1.2.80 > 192.168.1.1.60213: . 93125:94585(1460) ack 668 win 14343

b.) Testing if Jumbo Frames are enabled with ping

Testing Jumbo Frames with ping command on Linux

linux:~# ping 192.168.1.1 -M do -s 8972
PING 192.168.1.1 (192.168.1.1) 8972(9000) bytes of data.
9000 bytes from 192.168.1.1: icmp_req=1 ttl=52 time=43.7 ms
9000 bytes from 192.168.1.1: icmp_req=2 ttl=52 time=43.3 ms
9000 bytes from 192.168.1.1: icmp_req=3 ttl=52 time=43.5 ms
9000 bytes from 192.168.1.1: icmp_req=4 ttl=52 time=44.6 ms
--- 192.168.0.1 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3003ms
rtt min/avg/max/mdev = 2.397/2.841/4.066/0.708 ms

If you get insetad an an output like:

From 192.168.1.2 icmp_seq=1 Frag needed and DF set (mtu = 1500)
From 192.168.1.2 icmp_seq=1 Frag needed and DF set (mtu = 1500)
From 192.168.1.2 icmp_seq=1 Frag needed and DF set (mtu = 1500)
From 192.168.1.2 icmp_seq=1 Frag needed and DF set (mtu = 1500)

--- 192.168.1.1 ping statistics ---
0 packets transmitted, 0 received, +4 errors

This means a packets with maximum MTU of 1500 could be transmitted and hence something is not okay with the Jumbo Frames config.
Another helpful command in debugging MTU and showing which host in a hop queue support jumbo frames is Linux's traceroute

To debug a path between host and target, you can use:

linux:~# traceroute --mtu www.google.com
...

If you want to test the Jumbo Frames configuration from a Windows host use ms-windows ping command like so:

C:\>ping 192.168.1.2 -f -l 8972
Pinging 192.168.1.2 with 8972 bytes of data:
Reply from 192.168.1.2: bytes=8972 time=2ms TTL=255
Reply from 192.168.1.2: bytes=8972 time=2ms TTL=255
Reply from 192.168.1.2: bytes=8972 time=2ms TTL=255
Reply from 192.168.1.2: bytes=8972 time=2ms TTL=255
Ping statistics for 192.168.1.2:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 2ms, Maximum = 2ms, Average = 2ms

Here -l 8972 value is actually equal to 9000. 8972 = 9000 – 20 (20 byte IP header) – 8 (ICMP header)