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Here follows the Apache configuration I found working to set a repository read-only and read-write permissions. Consider read-write permissions are given by adding a user to both read-allowed and write-allowed LDAP groups, while read-only permissions are given through the read-allowed LDAP group.
AuthName “SmartLab Directory Server”
Require ldap-group cn=read-allowed,ou=groups,dc=smartlab,dc=net
Require ldap-group cn=write-allowed,ou=groups,dc=smartlab,dc=net