n00b's questions

During OS installation, I created only one account. Let's call it howdy. I thought it would have sudo privileges but I was wrong.

I scoured the internet and this forum to find out how to add howdy to the sudoers' list. I was under the impression that usermod -a -G sudo username would work. I opened a root terminal and issued the command. I closed it.

Next I opened a normal terminal and issued the following command: sudo gedit /etc/openvpn/update-resolv-conf

The following are the error messages:

howdy@wendy:~$ sudo gedit /etc/openvpn/update-resolv-conf
sudo: unable to resolve host wendy
[sudo] password for howdy: 
howdy is not in the sudoers file.  This incident will be reported.
[sudo] password for howdy: 

Furthermore I discovered that my root password has changed to the password for howdy. This is odd.

So when I opened a root terminal I now had to enter the password for howdy (the original root password did not work) and issued the command visudo and scrolled down to the phrase # Allow members of group sudo to execute any command My account called howdy is not on it.

I need help with the following:

1. Undo the changes brought about by usermod -a -G sudo username, especially to revert the root password to the original password I entered during OS installation. I don't know what the parameters -a and -G do.

2. Show me how to add my account called howdy to the sudoers' list.

I notice that whenever I use the command sudo apt-get -y autoremove quite a number of packages that I need is on the list to be removed.

After going through some of the posts on this forum, I have the impression that the command removes packages that have been automatically installed. To prevent autoremoval of a package, I will have to mark it as

sudo apt-get install <package-name>

Suppose I have 120 packages earmarked for autoremoval.

How do I mark them as manually installed with a single command?

I have a question about the following command:

apt-cache search java | awk '{print($1)}' | grep -E -e '^(ia32-)?(sun|oracle)-java' -e '^openjdk-' -e '^icedtea' -e '^(default|gcj)-j(re|dk)' -e '^gcj-(.*)-j(re|dk)' -e 'java-common'

Owing to my limited IT knowledge, am I right to say that the (ia32-) in the above command refers to 32-bit software? If it is, then I assume that the above command is for 32-bit installed OS.

However I installed a 64-bit OS.

What is the correct parameter for 64-bit software? Is it (amd64-) or (ia-64) or (x86_64-)?

Any expert help is much appreciated.

I wish to change a menu entry in grub.cfg, for example:

From

### BEGIN /etc/grub.d/10_linux ###
menuentry 'Ubuntu is wonderful'

To

### BEGIN /etc/grub.d/10_linux ###
menuentry 'Ubuntu is world famous'

I came across the following example of how to use iptables to block internet access when the VPN connection is terminated abruptly:

iptables -A INPUT -i lo -j ACCEPT
iptables -A OUTPUT -o lo -j ACCEPT #allow loopback access
iptables -A OUTPUT -d 255.255.255.255 -j ACCEPT #make sure you can communicate with any DHCP server
iptables -A INPUT -s 255.255.255.255 -j ACCEPT #make sure you can communicate with any DHCP server
iptables -A INPUT -s 192.168.0.0/16 -d 192.168.0.0/16 -j ACCEPT #make sure that you can communicate within your own network
iptables -A OUTPUT -s 192.168.0.0/16 -d 192.168.0.0/16 -j ACCEPT
iptables -A FORWARD -i eth+ -o tun+ -j ACCEPT
iptables -A FORWARD -i tun+ -o eth+ -j ACCEPT # make sure that eth+ and tun+ can communicate
iptables -t nat -A POSTROUTING -o tun+ -j MASQUERADE # in the POSTROUTING chain of the NAT table, map the tun+ interface outgoing packet IP address, cease examining rules and let the header be modified, so that we don't have to worry about ports or any other issue - please check this rule with care if you have already a NAT table in your chain
iptables -A OUTPUT -o eth+ ! -d a.b.c.d -j DROP # if destination for outgoing packet on eth+ is NOT a.b.c.d, drop the packet, so that nothing leaks if VPN disconnects

I have installed iptables-persistence and would like to know how to use the above to work with iptables.

Any help would be much appreciated.

P.S.: I do not have much IT knowledge and even less of Ubuntu. Could someone explain to me how does one obtain the value 192.168.0.0/16 ?

After reading the following two posts:

Trying to install an openVPN GUI messed up sudoers

Standards accounts are able to get root access using sudo without password request

I would like to learn how to perform a backup of /etc/sudoers file so that I can restore it in the event of a mess-up after installing a non-Ubuntu-package-ready software.

Any help would be much appreciated.

I am using Ubuntu 12.04.2 LTS.

If I issue the following command

sudo gedit /etc/NetworkManager/NetworkManager.conf

and change the line

dns=dnsmasq

to

#dns=dnsmasq

What will happen? Will I disable or enable DNS caching?

Additional notes:

I have been told that since I am using a VPN service, it would be better for me to do the above.

I am using Ubuntu 12.04.2 LTS, 64-bit, OpenVPN client 2.3.1

How do I prevent OpenVPN from autostarting at boot-up or reboot?

My current location is thousands of kilometers from Ubuntu's main server and I am obliged to use one of its mirrors in my country of domicile.

Do the owners of Ubuntu implement measures to periodically check their files (eg. ISOs, updates, security patches) at their mirror sites have not been tampered and/or malware/trojans have not been introduced by hackers?

My personal experience with installing and updating Ubuntu from the main server took at least two hours whereas the same process took just 10 to 15 minutes when I used Ubuntu mirror site available in my country.

On Microsoft Windows OS, at the command prompt, I issue the command ipconfig /flushdns to flush out the DNS resolver cache.

On Ubuntu 12.10, what is the corresponding command?

root@ubuntu:/etc/openvpn# ls -l test.conf -rw-r--r-- l root root 791 Mar 20 09:23 test.conf

What does the above command mean?

I am new to Linux and Ubuntu. I googled and read some articles stating that all ports are closed until they are opened manually by the user. Is it correct?

And what do you mean by "listening on a port" and "a port is established" in simple terms?

I wish to install the latest version of MinGW-w64 and was told the best way is to install it via Ubuntu's apt-get command.

How do I search for and install the latest version of MinGW-w64? I need the 64-bit version. What commands must I issue?

As always, thanks in advance for your help.

My installed OS is Ubuntu 12.10, 64 bit, English, kernel version 3.5.0.21

Which commands must I issue at the terminal window to find out the names of programs that connect to the internet immediately after Ubuntu boots up?

I need to run the following instructions:

Run build.sh as follows from a terminal window, where /path/to/expanded/folder is where build.sh is located, i.e. /home/user/Desktop/ap-kernelmodule-1.0.14-13:

cd /path/to/expanded/folder

sudo ./build.sh --kernel-dir /lib/modules/$(uname -r)/build

In my case, “the path to expanded folder” is home/sharon/savfl/ap-kernelmodule-1.0.14-13

Now, as for the kernel directory, I tried searching within almost all directories and managed to find the nearest match whose path is:

/usr/src/linux-headers-3.5.0.21-generic/kernel

So, I issued the following command:

sharon@sharon:~/savfl/ap-kernelmodule-1.0.14-13$ sudo ./build.sh home/sharon/usr/src/linux-headers-3.5.0.21-generic/kernel /lib/modules/3.5.0.21-generic/build

[sudo] password for sharon:

And I got the following error message:

Unknown Option: home/sharon/usr/src/linux-headers-3.5.0.21-generic/kernel

Usage: build.sh [options]

Options: --kernel-dir [DIRECTORY] :

DIRECTORY is to set kernel headers/makefiles directory to build kernel modules

The default is /usr/src/kernels/3.5.0-21-generic-x86_64

--kernel-rel [RELEASE] : RELEASE is to set which kernel release the kernel modules are builded for

The default is the current kernel release(3.5.0-21-generic)

--debug : Build the kernel modules with debugging information

--clean : Delete all generated files

--version : Display the version number of the build script

--help : Display this help

Can someone help me with this please?

Please note that prior to doing the above I have installed the linux-headers relevant to my current kernel version with the following command:

sudo apt-get install linux-headers-3.5.0.21-generic build-essential

I am new to Linux and Ubuntu; hence detailed how-to instructions would be most welcome.

Thanks in advance.

Instruction source : http://www.symantec.com/business/support/index?page=content&id=TECH95496

I did a fresh installation of Ubuntun 12.10 (kernel v3.5.0.21-generic, 64 bit, US English) on my computer after downloading the ISO from Ubuntu.com.

In order for one of my installed programs to work, I would like to downgrade the current kernel version to 3.2.0.24-generic

Questions:

1. Is it advisable to downgrade the current kernet version to an older one?

2. If the answer to (1) above is yes, how do I do it?

As always, detailed instructions on how to issue specific commands at the terminal window are welcome. I am new to Linux and Ubuntu.

Thanks in advance for your help.

I am new to Linux and Ubuntu and have tried changing to folders/directories with some difficulty.

Could someone explain why the following commands failed to change to the desired target folder/directory?

sharon@sharon:~$ cd Home 
bash: cd: Home: No such file or directory 
sharon@sharon:~$ cd /Home 
bash: cd: /Home: No such file or directory 
sharon@sharon:~$ cd Documents 
sharon@sharon:~/Documents$ cd Downloads 
bash: cd: Downloads: No such file or directory 
sharon@sharon:~/Documents$ cd /Downloads 
bash: cd: /Downloads: No such file or directory 
sharon@sharon:~/Documents$

I am using Ubuntu v12.10, 64bit, US English and am new to Linux and Ubuntu; hence detailed instructions are welcome.

Could someone show me where and how to download uudecode? Also specific commands on how to run/install uudecode would be most helpful.

The error message is as follows:

Validating available tools...

ERROR: Required utility missing: uudecode. Please install this
utility before using this Intelligent Updater package.

I have a source tarball: ap-kernelmodule-1.0.14-13.tar.gz I have to compile a kernel module out of it and was instructed to install development tools for my Ubuntu version (which is 12.10). The format is: sudo apt-get install linux-headers-$(uname -r) build-essential

Question #1: what is uname?

(When I installed Ubuntu, I input sharon as my name and which is also my account name. Whenever I open a terminal window, the words sharon@sharon: appear) Based on the format, I should input:

sudo apt-get install linux-headers-$(sharon -r) build-essential

or

sudo apt-get install linux-headers-$sharon -r build-essential

Question #2: Which of the above is correct?

(I am new to Linux and Ubuntu; hence detailed instructions are appreciated)

Could someone point out to me what Unity Panel looks like? I am using version 12.10, 64 bit, US English.