Thursday, July 3, 2014

Book review: Implementing SAMBA 4

Samba is a Windows implementation of sharing files and folders in Linux world. It is a favorite way of sharing your files on Linux with Windows users. But its use is much more than that. It can also act as servers of various roles.

Implementing SAMBA 4 is a book worth reading for Linux admins, system engineers or anybody who plan to use and master SAMBA configurations. In this version, a new feature, Active Directory Domain Controller (AD DC) is the most sought after by admins. This will let you configure SAMBA 4 as an AD DC. Using Debian 7 as the OS, I found no problem with it although many admins out there are using Fedora/Red Hat/CentOS as the main distros of choice.

Looking at the table of contents, I can say this book is not for beginners. So you have been warned. :)

Reading the sample chapter provided (Chapter 3), this book is an interesting to read. Steps are shown in pictures and clearly explained. Although I have little knowledge of AD DC, this book will make it easier for you to understand the steps needed by lots of screenshots.

Other topics mentioned that I found important and interesting are:
  • Understand the migration steps from Samba 3 to Samba 4
  • Integrate GNU/Linux operating system authentication into the AD
  • Understand the tasks and attention points when replacing a Microsoft Windows AD
If you are looking for a reading to better understand on how to configure SAMBA 4 for your AD DC, I recommend this kind of book.

Tuesday, June 17, 2014

Using mail command to send email using SMTP AUTH and no SSL

This is the command to send email using mail server with SMTP AUTH.

mail -v -s "Testing SMTP AUTH from mail command" -S smtp-auth=login -S smtp=smtp://mysmtpmailserver.com:587 -S from=me@mysmtpmailserver.com -S smtp-auth-user=me -S smtp-auth-password=mypassword mybuddy@somehost.com


-v = verbose
-s = subject
-S = option

For more options and info, please type man mail or info mail.
The last email address is the recipient address.
You can replace mail with mailx.

This command is useful to test your mailserver setup without login to GUI.

Have fun! :)

Monday, May 19, 2014

Apache redirection

I want to redirect all of my users who go to www.mywebmailserver.com to webmail.mywebmailserver.com. I have learned that from my googling, there are 2 popular ways to do it in apache web server. First, by using mod_rewrite and second, I can use redirect. The latter is the simplest. So I chose it. :)
Put this in vhost container.

NameVirtualHost www.mywebmailserver.com
<virtualhost www.mywebmailserver.com>
ServerName www.mywebmailserver.com
Redirect 301 / http://webmail.mywebmailserver.com/
</virtualhost>

In Mageia 4, the file is located in /etc/httpd/conf/vhosts.d and the file name is 00_default_vhosts.conf

That's it. Restart or reload apache for the changes to take effect.

Have fun!

Wednesday, May 14, 2014

Mageia 4 and HP Laserjet P1102 can't print

Hi all,

Since upgrading my Mageia 3 to 4, I never test my printer. It worked in Mageia 3. I never knew that it was going to give me a headache LoL. It didn't work!. I tried reinstalling the CUPS, the driver, and even changing the USB cable. It was after 2 weeks of busy schedule, I thought I wanted to try to find a solution.




After googling a bit, I found out from a post which I didnt remember to bookmark it, the culprit was the usblp module. Remove it by rmmod usblp and the printer could print again. I could say the problem is the module conflicts with the HP printer driver. Your mileage may vary.

Have fun!


Saturday, March 29, 2014

Chromium becomes sluggish

For so many months now I find my Chromium becomes sluggish. I thought it is because of scripts that I installed to play games on Facebook but I never tried to search for a solution until recently. A blog post by Kostya Vasilyev here reveals the real culprit. Since I disabled the plugin, my Chromium becomes stable and fast again. Thanks buddy. The steps are the same although the plugin name is not.

Here are the steps:

  1. Type  chrome://plugins in the address bar
  2. Find the plugin named Chromoting Viewer
  3. Disable it
  4. Done.


You may want to restart your browser although it is not necessary.

Tuesday, February 4, 2014

Mageia 4

Mageia 4 has been released on Feb 3rd 2014. For Mageia 3 users, you will get a notification to upgrade. Just click on it and after answer a few questions, you're set to go. I just did that and at the time of this writing, I'm using Mageia 4. 

From my point of view, I didn't notice any major differences in terms of usability beside the usual change of wallpapers, screensavers and a little bit of widgets. I'm sure, overtime I will find more and more. The Welcome dialog (see below) is a very good approach for newcomers and newbies alike to Mageia world. 

For those who are in search of a distro, Mageia is worth to try.

Enjoy!

Saturday, January 4, 2014

ralink firmware

In Mageia, not all packages from non-free repo are installed by default. One of them is ralink-firmware. In Mageia 2, various ralink wireless firmwares are separated in many packages like rt61-, rt2860-, rt2870-, rt3090-, rt73-. Now they are bundled in one package.

If you connect external wireless hardware that uses those rt chipsets family, you have to install this package. Please examine your syslog for the error in loading the driver such as this:

Dec 24 18:54:00 localhost kernel: ieee80211 phy1: rt2x00lib_request_firmware: Info - Loading firmware file 'rt2870.bin'
Dec 24 18:54:00 localhost kernel: ieee80211 phy1: rt2x00lib_request_firmware: Error - Failed to request Firmware

Install the firmware by issuing :

urpmi ralink-firmware

or you can use rpmdrake GUI for that.

Cheers.

Monday, July 1, 2013


I like this :
Google hopes that Quick UDP Internet Connections (QUIC), recently added to Chrome Canary, will help speed up HTTP traffic on the internet. The goal here is not to compete with SPDY, the protocol introduced four years ago, but to work in tandem with it by replacingTCP (Transmission Control Protocol), the current transport method, with UDP (User Datagram Protocol).
TCP makes sure that no data packets go missing at the protocol level and that they all land at their destination in the correct order. In Google's opinion, that's a disadvantage when combined with SPDY, in which several data streams between a browser and a web server flow over a single TCP socket – just one misplaced packet would block all of the data streams. The TCP stack in this case would also slow down the transmission of all of the streams.
QUIC uses the simpler UDP, which does not guarantee the transmission of individual packets. That means that the new protocol has to take care of this itself, but unlike with TCP, connections not affected by a particular loss don't have to wait for a new transmission. QUIC is designed to ensure fast connections, reduce packet losses with transmission pacing and minimise latency in the case of retransmission of a packet with forward error correction, and like SPDY, it only allows encrypted connections.
An extensive Google Docs document lays out the details and considerations behind QUIC. The Chromium source code includes a sample implementation for the server and the code for the client-side.
The key terms are : transmission pacing and forward error correction. 
Do you know their meanings? :)

Friday, December 21, 2012

Problem setting up HP LaserJet P1102 on Linux

If you have problem setting up driver for HP LaserJet P1102, it most probably because of Smart Install feature of the device. You can see it in dmesg output:


[353279.710023] usb 6-1: new high-speed USB device number 22 using ehci_hcd
[353279.824940] usb 6-1: New USB device found, idVendor=03f0, idProduct=002a
[353279.824944] usb 6-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[353279.824947] usb 6-1: Product: HP LaserJet Professional P1102
[353279.824950] usb 6-1: Manufacturer: Hewlett-Packard
[353279.824952] usb 6-1: SerialNumber: 000000000Q84CF03SI1c
[353279.826253] scsi16 : usb-storage 6-1:1.0
[353280.838094] scsi 16:0:0:0: CD-ROM            HP       Smart Install    1.0  PQ: 0 ANSI: 2
[353280.868209] sr1: scsi3-mmc drive: 0x/0x caddy
[353280.868365] sr 16:0:0:0: Attached scsi CD-ROM sr1
[353280.868452] sr 16:0:0:0: Attached scsi generic sg2 type 5

it is useful for Windows users as it will create a virtual cdrom drive in order to install the printer's driver. For Linux, this feature will prevent the setup utility to detect it as a USB printer as it sees it as a disk. The solution to this problem is by deactivating the feature using usb_modeswitch utility as below:


usb_modeswitch -m 4 -r 4 -v 0x03f0 -p 0x002a -M 55534243287E778400000000000006D0000000000000000000000000000000 -n

Please login as root before issuing the command.

The output is something like this:


Looking for default devices ...
   found matching product ID
   adding device
 Found device in default mode, class or configuration (1)
Accessing device 023 on bus 006 ...
Getting the current device configuration ...
 OK, got current device configuration (1)
Using first interface: 0x00
Using endpoints 0x04 (out) and 0x04 (in)
Not a storage device, skipping SCSI inquiry

USB description data (for identification)
-------------------------
Manufacturer: Hewlett-Packard
     Product: HP LaserJet Professional P1102
  Serial No.: 000000000Q84CF03SI1c
-------------------------
Looking for active driver ...
 No driver found. Either detached before or never attached
Setting up communication with interface 0
Using endpoint 0x04 for message sending ...
Trying to send message 1 to endpoint 0x04 ...
 Sending the message returned error -5. Trying to continue
Reading the response to message 1 (CSW) ...
 Response reading got error -5
 Device is gone, skipping any further commands
-> Run lsusb to note any changes. Bye.

(This output is after I ran the command once. You may see something like removing/deactivating the disk.) 

Then restart the printer or turn it off and on again. You should now run hp-setup utility to setup the printer and this time it can see the attached USB printer listed and you can select the printer to install the driver.

Hope this helps. Have fun!

Update: Whenever you restart your pc,  it can't connect to the printer. So this is not permanent solution. What you have to do is run the command of usb_modeswitch again and there you go. It will recognize the printer but this time you dont have to reinstall the driver. For permanent solution, from what I have read, I need to use Windows to run the printer's utility software but I never tried it before. if I have tried it, i will post it here.

Sunday, December 9, 2012

Postfix: smtp_address_preference

For mailserver/system  administrator :

If your mailserver has problem to connect to ipv6 address (especially if your mailserver doesn't support it) and throw errors something like this:

Dec 10 00:05:57 localhost postfix/smtp[16925]: connect to mta7.am0.yahoodns.net[2404:160:0:f:0:2:42c4:7621]:25: Network is unreachable
Dec 10 00:05:57 localhost postfix/smtp[16925]: connect to mta6.am0.yahoodns.net[2404:160:0:f:0:1:6288:d9ca]:25: Network is unreachable
Dec 10 00:05:57 localhost postfix/smtp[16925]: connect to mta7.am0.yahoodns.net[2404:160:0:f:0:2:42c4:7624]:25: Network is unreachable
Dec 10 00:05:57 localhost postfix/smtp[16925]: connect to mta6.am0.yahoodns.net[2404:160:0:f:0:1:43c3:a8e6]:25: Network is unreachable
Dec 10 00:05:57 localhost postfix/smtp[16925]: connect to mta6.am0.yahoodns.net[2404:160:0:f:0:1:42c4:7622]:25: Network is unreachable

then you may want to check the default smtp_address_preference parameter in main.cf. Most probably it is defaulted to ipv6 which is true on my postfix installation (Mageia). Change it to ipv4 to instruct postfix to look up MTA with ipv4 address only (which is I think supported by all major players like Yahoo!, Gmail and Hotmail for compatibility reason or they will lose lots of their customers) . So:

smtp_address_preference = ipv4

will save you before you consider to upgrade your infrastructure to ipv6. :-)

Have fun!

Sunday, September 9, 2012

Migrating and upgrading mailserver

I have new and powerful server for mail server. So now I am in the process of migrating my mail data and settings to the new server. But it is not as simple as copying a directory. It involves many things. Luckily some of them, you can just copy to the new server.

I am most concerned with the mail messages as they contain important messages for day-to-day operations and conversations. I will tell you more after the migration is complete.

cheers,

Tuesday, January 24, 2012

Perl: Terminal does not support AddHistory

If you see the error when running Perl shell, you need to install Term::ReadLine::Perl.




That's all there is to it. Have fun!.

changing manually wireless connection to be controlled by knetworkmanager

knetworkmanager is a Network Manager for KDE4. It is hated or liked by users and usually not in between. I personally like it although it has its fair share of bugs. But I like Mandriva's net_applet more. It is stable and more reliable. It is prefered by many Mandriva users. However, if you are stuck with recent problems (bug?) of perl in Mandriva Cooker like me, you are forced to use command line of wpa_supplicant or iwconfig or using gui application like knetworkmanager. 

In Mandriva, you can change which network manager control the wireless connection by changing the option in net_applet or you can manually change in file /etc/sysconfig/network-scripts/ifcfg-wlan0. If you want knetworkmanager in control of it, you just have to change this line to yes:


NM_CONTROLLED=yes


Sunday, January 22, 2012

Connecting to wireless AP with WPA/2 security using wpa_supplicant

Recently, my cooker updated perl packages and it broke all of drak* family especially drakconf and net_applet. net_applet is the network manager for Mandriva in applet form. I can also use draknetcenter. Now the problem is I cant open net_applet and knetcenter due to this error:
/usr/bin/perl: symbol lookup error: /usr/lib/libDrakX/auto/c/stuff/stuff.so: undefined symbol: Perl_Gthr_key_ptr
So how do I connect to wireless AP? I dont know how to use iwconfig to connect to such AP or can I? After googling, I found a solution: wpa_supplicant. In Mandriva, I just have to run this command (as root):
wpa_supplicant -Dwext -iwlan0 -c/etc/wpa_supplicant.conf &
If you have setup the connection before with draknetcenter, you dont have to edit the file wpa_supplicant.conf. If not, you have to manually edit the file to suit your environment. it is heavily documented. 

Then you have to run dhclient to get IP address from the AP or other dhcp server:
 dhclient wlan0

wlan0 is my wireless interface. Please change it according to your environment. I bet the broken packages will be updated sooner so that I can use net_applet again.

Have fun!

Monday, January 2, 2012

Happy New Year and distros for router

Happy New Year everbody. Hope 2012 will be a great year for Linux. In 2011, I tested several distros for different purposes. For routers, I found several free distros that serve as a really good gateway for my network. Among others are:

  1. Zentyal - this is the best distro for routers. Fully featured with webcache, url filtering, load balancing for multiple lines and has 32-bit and 64-bit version. It is based on Ubuntu.
  2. ClearOS - Also the best but it doesn't have 64-bit version (at the time of this writing. recently there's a 64-bit release but still in beta stage). Has many features as Zentyal. Based on Redhat.
  3. pfSense - this is not Linux-based. It is freeBSD-based firewall and router. It has bug with my servers pertaining to PCI-E. So I dumped it. It's good but the bug prevent it from being operational.
Others:
  • Untangle - didn't try it because the free version has no webcache feature.
  • Zeroshell - tried it but a little awkward to use.
So I chose Zentyal as my distro for my server router and info from its web, I need to add more RAM and bigger hard disk to serve more than 500 users.

Happy New Year everybody! Thanks for reading.