Para SLE 12 SP1 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/server:php:extensions:php5/SLE_12_SP1/server:php:extensions:php5.repo
zypper refresh
zypper install fann
Para SLE 12 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/server:php:extensions:php5/SLE_12/server:php:extensions:php5.repo
zypper refresh
zypper install fann
Para SLE 11 SP4 execute o seguinte como root:
zypper addrepo https://download.opensuse.org/repositories/server:php:extensions:php5/SLE_11_SP4/server:php:extensions:php5.repo
zypper refresh
zypper install fann