SL7: enable EPEL repos

there is a vast repo for packages not (officially?) maintainted by redhat. to enable this repo (called EPEL) the following steps are needed:

  1. get and install the epel rpm file:
    $ wget http://dl.fedoraproject.org/pub/epel/7/x86_64/e/epel-release-7-9.noarch.rpm
    $ rpm -ivh epel-release-7-9.noarch.rpm
    
  2. get the gpg key for epel:
    1. download key: $ wget https://getfedora.org/static/352C64E5.txt
    2. check fingerprint:
      1. get official fingerprint from website: https://getfedora.org/keys/
      2. compare to value from: $ gpg --with-fingerprint 352C64E5.txt
    3. import key: $ rpm --import 352C64E5.txt

src: tecmint.com, web-vision.de (german)