First login to your Debian system as root and execute "apt-get update" at the shell prompt. The output on your screen should appear similar to the following.
# apt-get update
Hit http://ftp.us.debian.org lenny Release.gpg
Ign http://ftp.us.debian.org lenny/main Translation-en_US
Hit http://volatile.debian.org lenny/volatile Release.gpg
Ign http://volatile.debian.org lenny/volatile/main Translation-en_US
Hit http://security.debian.org lenny/updates Release.gpg
Ign http://security.debian.org lenny/updates/main Translation-en_US
Hit http://ftp.us.debian.org lenny Release
Hit http://volatile.debian.org lenny/volatile Release
Hit http://security.debian.org lenny/updates Release
Ign http://ftp.us.debian.org lenny/main Packages/DiffIndex
Ign http://volatile.debian.org lenny/volatile/main Packages/DiffIndex
Ign http://ftp.us.debian.org lenny/main Sources/DiffIndex
Ign http://security.debian.org lenny/updates/main Packages/DiffIndex
Ign http://volatile.debian.org lenny/volatile/main Sources/DiffIndex
Hit http://ftp.us.debian.org lenny/main Packages
Ign http://security.debian.org lenny/updates/main Sources/DiffIndex
Hit http://ftp.us.debian.org lenny/main Sources
Hit http://volatile.debian.org lenny/volatile/main Packages
Hit http://security.debian.org lenny/updates/main Packages
Hit http://volatile.debian.org lenny/volatile/main Sources
Hit http://security.debian.org lenny/updates/main Sources
Reading package lists... Done
After the system successfully downloads data from the repositories execute "apt-get dist-upgrade -y" from the shell prompt to update your Debian OS to the latest available software. The update process may ask you questions for some of the software being upgraded due to significant configuration or OS changes. Once complete, ensure your system is up to date by executing "apt-get dist-upgrade -y" a second time and you should see the following on your screen.
# apt-get dist-upgrade -y
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
After all updates have been applied it is recommended that you perform a soft reboot of your server using the "shutdown -r now" command from the shell prompt. This is to ensure you boot into any new kernels that Aptitude may have installed.
