Ubuntu 14.04 Hash Sum mismatch problem.

Some update and upgrade session might corrupt the metadata of the package information in Ubuntu, more known as the “Hash Sum mismatch” error after the  apt-get update command. A workaround if the simple update command doesn’t work is you need to manually clean the package metadata record being produced, here’s how:

1. Run these series of command on your terminal:

   apt-get clean
   rm -rf /var/cache/apt/*
   rm -rf /var/lib/apt/lists/*

2. Then check if all works out by doing another package metadata update:

   apt-get update

3. Done.

Full information about the discussion here: (https://gitlab.com/gitlab-org/omnibus-gitlab/issues/628)

 

 

Fix for Elantech touchpad on Ubuntu 14.04

Since I recently got my new Lenovo G5070 notebook few days ago, I rush in to install second OS : Ubuntu 14.04, though installation process is tough, need to fix video card defaults, from fgrlx to intel graphics. Then another issue is wireless network RTL8723BE drops after each connection, but this article is about the touchpad: the ElanTech Touchpad, which by default not functioning well. Issues like there’s no switch off touchpad option in Ubuntu settings, multi-touch is not working, neither the scrolling.

Now to fix this issues, here’s the guide:

1. First, download the patch for the touchpad here.

2. Install dkms (if you haven’t done it yet)

sudo apt-get install dkms

3.  Go to the directory where you store the file and perform the following:

sudo dkms ldtarball psmouse-elantech-x551c.tar.gz
sudo dkms install -m psmouse -v elantech-x551c

4. Then reconfigure the driver

sudo rmmod psmouse
sudo modprobe psmouse
sudo update-initramfs -u -k all

5. Done

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.

How to block facebook on your linux based firewall

For most corporate network, social network are not allowed, and since facebook is one of the most popular social network site, it continuously add new IP address frequently. So blocking IP known to you alone is not enough. Here’s a better way to block IP owned by facebook (Only if you wish to block it in your network)

#> /usr/bin/whois -h whois.radb.net '!gAS32934' | head -n -1 | tail -n -1 | /usr/bin/xargs --max-args=1 | /usr/bin/xargs -I {} --max-args=1 /sbin/iptables -t mangle -I POSTROUTING -d {} -j DROP

 

 

tail -f with highlighting

A little help with perl

http://sysadminnotebook.blogspot.com/2012/09/tail-f-with-highlighting.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+SysadminNotebook+%28Sysadmin+Notebook%29

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.