Hardcore Linux

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Category Archives: Linux

Enabling CUPS remote administration via console

There are various way to enable  CUPS remote administration via console or Linux terminal. You can modify the /etc/cups/cupsd.conf and add those “Allow all” directives in several lines.

Here’s a quick and easier way to enable remote administration for CUPS:

1. Open a terminal

2. With root or sudo access, do:

$> cupsctl --remote-admin

3. Done.

error: Diskfilter writes are not supported Ubuntu 14.04

After a clean install or upgrade from 12.04 to 14.04 on raid or lvm setup, normally you will encounter this error, which is related to the setup I mentioned. From various test, I encounter a workaround to fix this error.

Modify /etc/grub.d/10_linux 

Replace quick_boot=1 with quick_boot=0

Done.

How to re-enable Ubuntu 13.04 systray to display Pidgin and other programs.

Previously, Ubuntu tweak, myUnity and other Unity tweaking tools can provide configuration to modify current whitelist for Unity’s system tray or systray. But with recent upgrade (as usual), it was suddenly gone and nowhere to be found.

But at last, there’s a workaround (again..pfff) for this, here’s how:

1. Add this PPA and update+upgrade your Ubuntu 13.04 system.

sudo add-apt-repository ppa:timekiller/unity-systrayfix
sudo apt-get update
sudo apt-get upgrade

2. Afterwards, restart Unity, press ALT+F2 (run application), then type in  unity, press ENTER key.

3. You must have  dconf-editor to modify configuration, if not yet installed, do this:

sudo apt-get install dconf-tools

4. Open dconf-editor and navigate to  com > canonical > unity > panel  and the “systray-whitelist” should be displayed there so you can enable some apps to be able to use the systray. From the default setting, change it to ‘all’ (yes with the single quote ““character)

5. Then configure Pidgin, from Tools > Preferences. Set the Show System Tray Icon to “always

6. Done.

 

 

 

 

Allow Standard User to connect to wifi on Ubuntu

Still using Ubuntu 12.04, and one of the problem we’ve encountered is it requires normal user to authenticated the designated admin user’s password when connecting to wireless network, which in my opinion doesn’t make sense. How can a normal user access internet over wifi if they aren’t allowed to do so?

Check what google search has to offer, I finally found a fix for this. Adding policykit rules for wifi users.

Create or modify a file  etc/polkit-1/localauthority/50-local.d/52-wifi-management.pkla


$> sudo gedit etc/polkit-1/localauthority/50-local.d/52-wifi-management.pkla

and then enter the following


[Wifi management]
Identity=unix-group:netdev
Action=org.freedesktop.NetworkManager.*
ResultAny=no
ResultInactive=no
ResultActive=yes

and save on exit.

Add the user to the netdev group


$> sudo usermod -a -G ftp jerry

Restart the system and standard user should now be able to connect to wifi..

Done.

tail -f with highlighting

Getting WAN IP on console or shell script.

There are few other guide in getting your current WAN IP on Linux console or fetching it within a shell script. But this one works for me.

1. To get the current WAN IP:

$> echo "$(wget http://automation.whatismyip.com/n09230945.asp -O - -o /dev/null)"

2. For LAN IP address/es:

$> ifconfig | grep 'inet addr:'| grep -v '127.0.0.1' | cut -d: -f2 | awk '{ print $1}'

 

 

Hide network-manager applet in Ubuntu 12.04 when using ifup.

Wish to hide the nm-applet when decide to use conventional ifup instead of network-manager? Here’s how:

1. Install Gconf-Editor:

$> sudo apt-get install gconf-editor

2. Run gconf-editor and go to: Apps –> nm-applet

3. Uncheck the  setting called  show-applet

4. Done.

Ubuntu 12.04 /etc/resolv.conf 127.0.0.1 implementation with dnsmasq

On the current version of Ubuntu (12.04), you might notice that the current /etc/resolv.conf file always record a nameserver 127.0.0.1 which then resolv dns via dnsmasq, but most of the time after test few things, I found it more problematic. It always disregard my local DNS server, and goes directly to the DNS of my ISP.

If you’re having the same problem like mine, here’s a quickfix:

1. Modify the configuration /etc/NetworkManager/NetworkManager.conf

$> sudo gedit /etc/NetworkManager/NetworkManager.conf

2.  Comment the line that contain “dns=dnsmasq

[main]
...
#dns-masq

3. Then restart the network-manager

$> sudo  service network-manager restart

4. Done

 

 

Installing KVM with OpenVSwitch on Ubuntu 12.04

Here’s a good article from http://blog.allanglesit.com/, I myself tried it my in test server and it’s working great, though I’m still new with OpenVSwitch.

The article has been released for Ubuntu 12.04 system. I also found out that the KVM version currently available in Ubuntu 12.04 has better performance compare to 10.04, which I think is a good sign when planning to deploy KVM host for your VMs.

The actual URL: http://blog.allanglesit.com/2012/03/linux-kvm-ubuntu-12-04-with-openvswitch/

Done.

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