For SLE 15 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:steffens:SmartClient:server/SLE_15/home:steffens:SmartClient:server.repo
zypper refresh
zypper install perl-Unix-Syslog
For SLE 12 SP4 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:steffens:SmartClient:server/SLE_12_SP4/home:steffens:SmartClient:server.repo
zypper refresh
zypper install perl-Unix-Syslog
For SLE 12 SP1 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:steffens:SmartClient:server/SLE_12_SP1/home:steffens:SmartClient:server.repo
zypper refresh
zypper install perl-Unix-Syslog