For openSUSE Leap 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/security:Stunnel/openSUSE_Leap_15.6/security:Stunnel.repo
zypper refresh
zypper install stunnel
For openSUSE Leap 15.3 ARM run the following as root:
zypper addrepo https://download.opensuse.org/repositories/security:Stunnel/openSUSE_Leap_15.3_ARM/security:Stunnel.repo
zypper refresh
zypper install stunnel
For SLE 15 SP3 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/security:Stunnel/SLE_15_SP3/security:Stunnel.repo
zypper refresh
zypper install stunnel
For SLE 15 SP2 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/security:Stunnel/SLE_15_SP2/security:Stunnel.repo
zypper refresh
zypper install stunnel
For SLE 15 SP1 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/security:Stunnel/SLE_15_SP1/security:Stunnel.repo
zypper refresh
zypper install stunnel
For SLE 15 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/security:Stunnel/SLE_15/security:Stunnel.repo
zypper refresh
zypper install stunnel
For SLE 12 SP5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/security:Stunnel/SLE_12_SP5/security:Stunnel.repo
zypper refresh
zypper install stunnel