[Alex--]

No firewall. localhost is resolvable from both local files and DNS (nsswitch.conf says "hosts: files dns", so it gets it from /etc/hosts).

All libraries needed for ldap are present:

t115# ldd /opt/zimbra/openldap/libexec/slapd
        libsasl2.so.2 => /opt/zimbra/cyrus-sasl/lib/libsasl2.so.2 (0x00e6d000)
        libssl.so.4 => /lib/libssl.so.4 (0x00cb7000)
        libcrypto.so.4 => /lib/libcrypto.so.4 (0x002cf000)
        libresolv.so.2 => /lib/libresolv.so.2 (0x00d8f000)
        libpthread.so.0 => /lib/tls/libpthread.so.0 (0x00111000)
        libc.so.6 => /lib/tls/libc.so.6 (0x007ea000)
        libdl.so.2 => /lib/libdl.so.2 (0x00b50000)
        libgssapi_krb5.so.2 => /usr/lib/libgssapi_krb5.so.2 (0x00e20000)
        libkrb5.so.3 => /usr/lib/libkrb5.so.3 (0x00123000)
        libcom_err.so.2 => /lib/libcom_err.so.2 (0x00b23000)
        libk5crypto.so.3 => /usr/lib/libk5crypto.so.3 (0x0019b000)
        libz.so.1 => /usr/lib/libz.so.1 (0x00d6c000)
        /lib/ld-linux.so.2 (0x0022f000)
t115#