$ ldapwhoami -YEXTERNAL -H ldapi:/// SASL/EXTERNAL authentication started SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth SASL SSF: 0 dn:cn=config
Only question now is if this is enough to prevent people from binding as cn=config on ldap://<public-IP>/, where the server is also listening.
Without any other authz-regexps in place, the only other possibility is to use a client cert that slapd trusts, whose subject DN is "cn=config". Aside from that, no, there is no other way anyone can bind to this identity.
/Peter