apt policy
Package files:
 100 /var/lib/dpkg/status
     release a=now
 500 http://apt.syncthing.net syncthing/release amd64 Packages
     release o=Syncthing,a=syncthing,n=debian,l=Syncthing,c=release,b=amd64
     origin apt.syncthing.net
 100 http://deb.debian.org/debian buster-backports/main amd64 Packages
     release o=Debian Backports,a=buster-backports,n=buster-backports,l=Debian Backports,c=main,b=amd64
     origin deb.debian.org
 500 https://deb.nodesource.com/node_13.x stretch/main amd64 Packages
     release o=Node Source,n=stretch,l=Node Source,c=main,b=amd64
     origin deb.nodesource.com
 500 http://archive.ubuntu.com/ubuntu bionic/restricted amd64 Packages
     release v=18.04,o=Ubuntu,a=bionic,n=bionic,l=Ubuntu,c=restricted,b=amd64
     origin archive.ubuntu.com
 500 http://archive.ubuntu.com/ubuntu bionic/multiverse amd64 Packages
     release v=18.04,o=Ubuntu,a=bionic,n=bionic,l=Ubuntu,c=multiverse,b=amd64
     origin archive.ubuntu.com
 500 http://archive.ubuntu.com/ubuntu bionic/universe amd64 Packages
     release v=18.04,o=Ubuntu,a=bionic,n=bionic,l=Ubuntu,c=universe,b=amd64
     origin archive.ubuntu.com
 500 http://security.ubuntu.com/ubuntu bionic-security/restricted amd64 Packages
     release v=18.04,o=Ubuntu,a=bionic-security,n=bionic,l=Ubuntu,c=restricted,b=amd64
     origin security.ubuntu.com
 500 http://security.ubuntu.com/ubuntu bionic-security/universe amd64 Packages
     release v=18.04,o=Ubuntu,a=bionic-security,n=bionic,l=Ubuntu,c=universe,b=amd64
     origin security.ubuntu.com
 500 http://security.ubuntu.com/ubuntu bionic-security/multiverse amd64 Packages
     release v=18.04,o=Ubuntu,a=bionic-security,n=bionic,l=Ubuntu,c=multiverse,b=amd64
     origin security.ubuntu.com
 500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 Packages
     release v=18.04,o=Ubuntu,a=bionic-security,n=bionic,l=Ubuntu,c=main,b=amd64
     origin security.ubuntu.com
 100 http://ftp.debian.org/debian stretch-backports/main amd64 Packages
     release o=Debian Backports,a=stretch-backports,n=stretch-backports,l=Debian Backports,c=main,b=amd64
     origin ftp.debian.org
 500 http://security.debian.org/debian-security stretch/updates/non-free amd64 Packages
     release v=9,o=Debian,a=oldstable,n=stretch,l=Debian-Security,c=non-free,b=amd64
     origin security.debian.org
 500 http://security.debian.org/debian-security stretch/updates/contrib amd64 Packages
     release v=9,o=Debian,a=oldstable,n=stretch,l=Debian-Security,c=contrib,b=amd64
     origin security.debian.org
 500 http://security.debian.org/debian-security stretch/updates/main amd64 Packages
     release v=9,o=Debian,a=oldstable,n=stretch,l=Debian-Security,c=main,b=amd64
     origin security.debian.org
 500 http://mirror.leaseweb.com/debian stretch/contrib amd64 Packages
     release v=9.13,o=Debian,a=oldstable,n=stretch,l=Debian,c=contrib,b=amd64
     origin mirror.leaseweb.com
 500 http://mirror.leaseweb.com/debian stretch/non-free amd64 Packages
     release v=9.13,o=Debian,a=oldstable,n=stretch,l=Debian,c=non-free,b=amd64
     origin mirror.leaseweb.com
 500 http://mirror.leaseweb.com/debian stretch/main amd64 Packages
     release v=9.13,o=Debian,a=oldstable,n=stretch,l=Debian,c=main,b=amd64
     origin mirror.leaseweb.com
Pinned packages:
     znc-perl -> 1.7.2-3~bpo9+1 with priority 500
     znc-dev -> 1.7.2-3~bpo9+1 with priority 500
     znc-python -> 1.7.2-3~bpo9+1 with priority 500
     znc -> 1.7.2-3~bpo9+1 with priority 500
     znc-tcl -> 1.7.2-3~bpo9+1 with priority 500