Administer Ubuntu using a web browser from any computer or operating system

Webmin is some fun software designed to let a user administrate his/her system using a web browser. The web browser can be running in the computer itself, or on another computer on the same network or even the Internet (provided the network is configured correctly). Webmin is geared around server configuration, but it still offerers one or two tools for more humble users.

Unfortunately it isn't contained within the Ubuntu software repositories, and must be downloaded from the Webmin site. Additionally, sev-

eral dependencies must be manually taken care of. Start by visiting http://www.webmin.com/download.html and download the Debian package (if an Ubuntu package is available, download that instead, but at the time of writing both Debian and Ubuntu packages were combined).

open a terminal prompt and type the following, which will install the dependencies needed by webmin:

$ sudo apt-get install libnet-ssleay-perl libauthen-pam-perl libio-pty-perl 1ibmd5-per1

Then to install the Webmin package, type the following (assuming it's been downloaded to the desktop): $ sudo dpkg -i ~/Desktop/webmin_1.420_a11.deb

Obviously you should replace the filename with that which you downloaded.

Once installation has completed, Webmin is ready to use immediately. To access it from your own machine, open a web browser and type the following address: https://1ocalhost:10000

To access it from another computer, you'll need to know your computer's IP address. This can be discovered by right-clicking the NetworkManager icon, selecting Connection Information, and looking at the IP Address line in the dialog box that appears. For example, the computer I installed Webmin into had the IP address of 192.168.1.6, so to connect from my Apple Macbook computer I open the Safari web browser and type the following into the address bar:

https://192.168.1.6:10000

Regardless of how you connect, the first time you do so you'll be warned about an invalid security certificate. This happens because Webmin uses the encrypted https:// web browser protocol and this relies on security certificates that are issued by a handful of Internet agencies. Because getting one of these certificates is impractical for every installation, Webmin generates its own certificate for the purposes of allowing https:// connections. 22

22. If you get hold of a digital certificate, or already own one for the machine that Webmin is installed on, you can configure Webmin to work with it instead of its own self-generated certificate. Once it's installed, click Webmin on the left of the window and then Webmin Configuration. Then click the SSL Encryption icon and click the Upload Certificate tab.

Figure 3.26: Adding a security exception for Webmin (see Tip 143, on page 184)

Therefore on each machine you use to access Webmin, you must tell the web browser to either ignore the seemingly insecure certificate, or add an exception, as in the case of Firefox under Ubuntu—click the Or you can add an exception link when the warning dialog box appears and then click the Add Exception button. Then click the Get Certificate button in the dialog box that appears and then click Confirm Security Exception, as shown in Figure 3.26.

Following this you'll see a username and password login. Type in your standard Ubuntu username/password combination and you should be presented with Webmin's dashboard. On the left are the system administration categories you can choose from. You can choose to add users, for example, by clicking the System link and selecting Users and Groups. You can edit the book loader menu by clicking the Hardware link and selecting GRUB Boot Loader. You an even run shell commands by clicking Others and then Command Shell.

Remember that, if you have activated Ubuntu's firewall (see Tip 37, on page 93), you'll need to add an outgoing rule to allow Webmin to be accessed by computers on the network. Bear in mind too that if you have a computer that directly connects to the Internet (that ISN'T behind a NAT firewall, such as that provided by a broadband router) then your Webmin login screen will be accessible by the entire Internet. You should ensure that you keep Webmin up to date if this is the case, to keep on top of potential security vulnerabilities.

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