1.
sudo sh -c "echo 'deb http://download.opensuse.org/repositories/home:/colomboem/xUbuntu_16.04/ /' > /etc/apt/sources.list.d/dukto.list" sudo apt-get update sudo apt-get install dukto
2.
W: GPG error: http://download.opensuse.org/repositories/home:/colomboem/xUbuntu_16.04 Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E3757B8E0D988D6E
W: The repository 'http://download.opensuse.org/repositories/home:/colomboem/xUbuntu_16.04 Release' is not signed.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: There is no public key available for the following key IDs:
E3757B8E0D988D6E
3.
You can add the repository key to apt. Keep in mind that the owner of the key may distribute updates, packages and repositories that your system will trust (more information). To add the key, run:
wget -nv https://download.opensuse.org/repositories/home:colomboem/xUbuntu_16.04/Release.key -O Release.key sudo apt-key add - < Release.key sudo apt-get update
4.
W: http://download.opensuse.org/repositories/home:/colomboem/xUbuntu_16.04/Release.gpg: Signature by key 1A2E38D61775C3963A039A87E3757B8E0D988D6E uses weak digest algorithm (SHA1)
W: GPG error: http://download.opensuse.org/repositories/home:/colomboem/xUbuntu_16.04 Release: The following signatures were invalid: KEYEXPIRED 1537363118
W: The repository 'http://download.opensuse.org/repositories/home:/colomboem/xUbuntu_16.04 Release' is not signed.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
5.
grep -iR opensuse /etc/apt/sources.list*
sudo sed -i '/opensuse/ s/^/#/' /etc/apt/sources.list.d/*.list
6. OK