linux
VirtualBox Manager Pro – UI Updates and Stability
May 23rd
I have added a variety of user interface updates to the pro version. In addition to the toast popups actual notifications add a sence of feedback and depth to the program. I want the program to feel that its actually aware of what you are doing and processing interactions accordingly. I feel with recent enhancements this is becoming more and more the case.
I have fixed a couple of potential situations where an i/o exception can occur. I have also added enhancements that clarify a particular action based on the current state of setting. All in all the depth and feedback offered by the application is improving.
Without substantial feedback/comments by actual users, I see very little confusion using the app and no bugs. Every action performs accordingly. The primary situation I think users may encounter is the inability to login. In such a situation the connecting dialog will just continue to spin. VirtualBox Manager is designed for users to first login to a host using password authentication. Therefore for each host the first connection must be made to an ssh server with PasswordAuthentication set to yes in /etc/ssh/sshd_config. Withe the correct host/port/username/password set in the app, and port forwarding properly configured in a users router/network a connection will occur. The user can then click the menu, and select generate key; which generated a new 1024 bit DSA key. The user can view the private and public keys directly from buttons in the menu. There are strategic dialog boxes that state the user can then upload the key to the server, which automatically appends it to the bottom of ~/.ssh/authorized_keys2. Pressing upload automatically enabled key login for the particular host. Enabling and disabling key login is done via the hosts configuration options accessible on the main screen.
There are many checks to prevent confusion. A user cannot enable key login unless there is a key. Keys cannot be displayed/uploaded before they are created; which would be an i/o exception. There is also a warning when a user tries to generate a key when a key already exists. This can cause a problem that will prevent other hosts from loggin in; if the key changes it will no longer match the public key stored on the host. A dialog will appear explaining that password login will be re-enabled for the host, and that when the key is uploaded password authentication will be used. If a new key is generated the user must disabled key authentication for other hosts configured in the app; once logged in to other hosts using password auth the user can easily upload the new public key to the server, reestablishing key based authentication for the respective host.
After a public key is uploaded to the server password authentication can be disabled. This substantially diminishes and practically eliminates the possibility of a brute force intrusion.
The pro version adds support for 20 hosts, and 20 machines per host. This is done using a ScrollView wrapped around each activity. Its a logical addition. If users request support for more hosts it can easily be added.
I want to change the oncreate structure to each of the three activities. I want to initialize the buttons in a background thread. While the UI is fast and there is no visible delay I would like to code the oncreates as such. Frankly given the speed of recent phones I don’t think there will be any visible differences. Theoretically on a slower processor the activity would display with no button, and then as the thread processes the views they will display on the screen one by one.
I will add some additional features in time, but until comments start rolling in a new project is in the works. Linux Manager Pro. I’ll posts as it develops.
Nvidia Driver on Linux – Easy, and Quick
Feb 7th
- Image via CrunchBase
There is a buzz that installing the Linux based Nvidia accelerated graphics driver is complicated. I consider it rather straight forward. First install build-essential, and the headers for your kernel. Those may appear to be some bigs words in the previous sentence, but it is really one line in a terminal window. Build essential installs GCC and its dependencies:
sudo apt-get install build-essential linux-headers-$(uname -r)
Now download the latest and greatest Nvidia driver. Choose the correct build type for your architecture. Conveniently save the file to your desktop and rename it to nvidia.run. The change your tty to another. To change to tty2 press control-alt f2.
Shut down gdm, which will stop X11:
sudo /etc/init.d/gdm stop
Or if you are using the new process manager in Ubuntu 9.10 you can use also:
sudo service gdm stop
Then execute the Nvidia installation script. Login to the command prompt and navigate to the desktop:
cd Desktop
sudo sh nvidia.run
Basically answer yes to everything, let the driver compile, and then when it asks you to configure the xorg.conf file, let it. Nowadays the Nvidia driver basically works out of the box. In the past, with Ubuntu in particular, you had to comment out the included driver in Ubuntu’s modules package, otherwise the custom compiled driver would not load on startup. The open source driver used to be commented out in /etc/default/linux-restricted-modules-common (comment NV); note that this is not needed any more except in Hardy (8.04).
Then start your gdm session, which will take you back to the login window, or your desktop depending on your startup settings:
sudo /etc/init.d/gdm start
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Linux Anti Virus for Websites
Jan 30th
Image via Wikipedia
Just because you run linux does not mean you completely forgo anti virus. Your website can be broadcasting Windows viruses or malware. Clamav, run from the command line, will scan your web directories recursively to identify various concerns. Install Clamav:
Then you can run Clam manually or you can install a cron job for it to be run automatically. Running Clam as root allows you to scan the higher level directories. The following command will scan the entire computer and remove viruses and malware:
sudo clamscan -r / --remove
Set this as a cronjob to run in the middle of the night; add it to the root crontab list:
0 2 * * * clamscan -r / --remove
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- Scan your Linux machine for viruses with ClamTk (ghacks.net)
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Detecting a Security Breach – Ubuntu and Linux Machine
Jan 25th
Detecting a security breech is sometimes as easy as logging into the machine, using ssh, and viewing the last login attempt from a completely unrecognized ip address or domain. Subsequently check your auth.log file, in /var/log, for login attempts. If you see countless failed login attempts you have been the victim of a brute from attack. In gedit, or nano you can search for “attempt” or “access”. When several failed login attempts occur a log entry saying “possible breaking attempt” is posted. The first think a hacker will do, on a Linux machine, is attempt to change the root password, which will lock down the machine completely. If they cannot change the root password, they may just try and install a backdoor to the particular user that was breached. A backdoor can be a daemon running on any port, so check with “ps aux | grep user”. Grepping the ps command will bring up all of your active processes and if any process name looks funny you have identified a concern. You can also check what ports are accepting communication (open). A backdoor can also be an installed authorized key, which will allow password-less ssh access to the system.
Ultimately if a hacker changes the root password of your machine, there is nothing you can do. You must either restore from a backup, or rebuild the entire machine. No questions asked.
Linux CUPS Configuration – Foomatic
Jan 16th
First install all needed packages. Your going to need cups, and the client, and the foomatic and openprinting drivers.
sudo apt-get install cupsys cupsys-client
Then install everything in:
sudo apt-cache search foomatic
If its an HP printer your going to want that library. HP has an auto setup script. Install the package and run:
sudo hp-setup
Installing all the foomatic, openprinting, and hp drivers the hp-setup script will detect printers on the network and will give you options as to which driver to use. To manage everything I recommend webmin. Download webmin from sourceforge, and use dpkg to install it. It will say dependencies are needed so just run:
sudo dpkg --configure -a
Webmin will install and you will access it from:
https://localhost:10000
You can configure other printers (other than HP) from here. You should set the printer to static ip address then you will configure the printer to that IP and port 9100. Select the corresponding from from the CUPS menu at the bottom of the printer configuration page. Some printers need a driver straight from openprinting.com. Copy the ppd to a folder in /var/share/ppd/openprinting. Create a folder with the manufacturers name if need be. Install it the same way as other printers (through webmin), and select the corresponding ppd drivers, in the CUPS section, the add new printer configuration page.
Scrub – File Shredding for Linux
Dec 26th
With this handy little app you can shred files and folders, but more conveniently you can shred your entire free space. Just make sure you’ve erased all the files you want to shred. Empty the trans, issue:
sudo apt-get autoclean && localepurge
Download scrub from Sourceforge:
http://sourceforge.net/projects/diskscrub
Its a simply source so configure, make and install. It will install a binary in the global path. You can run it at a user or as root. Run scrub accordingly to shred all free space:
sudo scrub -X ~/scrub
This will create a directory, in your home folder, called scrub and fill it with files created from free space. It will then shred them substantially. You can use the -r option, with scrub, to attempt to delete the scrub folder afterward, but it never worked for me. Just make a script as follows:
#!/bin/bash
sudo scrub -X ~/scrub
rm -r ~/scrub
Make it executable, and this will ensure that the folder is deleted after the process is complete. You can make this a cronjob to run it at night. Like at 3 in the morning. It will take hours on a relatively large drive. Maybe an hour per 50 gigs.