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The output of your command "$ netstat -an | grep LISTEN | grep 80" is:

tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN     
unix  2      [ ACC ]     STREAM     LISTENING     88380    /run/user/1000/gnupg/S.gpg-agent.ssh
unix  2      [ ACC ]     STREAM     LISTENING     817461   /var/run/apache2/cgisock.198064