Dpkg

Missing key id NO_PUBKEY

# apt-key adv --keyserver keyserver.ubuntu.com --recv  <keyid>

Package source which resolves to IPv6 adresses causes sometimes problems

To force the usage of the returned IPv4 adresses do:

$ echo 'Acquire::ForceIPv4 "true";' | sudo tee /etc/apt/apt.conf.d/99force-ipv4

Packages from a specific source

Prequisite: dctrl-tools

sudo apt-get install dctrl-tools

Show packages

For example all PPA packages

sudo grep-dctrl -sPackage . /var/lib/apt/lists/ppa*_Packages

From where is my package installed?

sudo apt-cache policy <package>

Does my file match the checksum from the package?

If you fear you are hacked verify your binaries!

Prequisite: debsums

sudo apt-get install debsums

Verify packages

sudo debsums <package name>

$ sudo debsums unhide.rb
/usr/bin/unhide.rb                                                            OK
/usr/share/doc/unhide.rb/changelog.Debian.gz                                  OK
/usr/share/doc/unhide.rb/copyright                                            OK
/usr/share/lintian/overrides/unhide.rb                                        OK
/usr/share/man/man8/unhide.rb.8.gz                                            OK