After upgrading wu-ftpd-2.5.0-2.i386.rpm to wu-ftpd-2.5.0-5.6.0.i386.rpm ftpd stoped working when invoked as /usr/sbin/wu.ftpd -Sa. It accepts connections and shows them in ps has connected but the connection lingers before even displaying the banner.
Solved. (works for me). It was due to a firewall missconfiguration. The new ftpd waits for much longer for auth response than the previous package, thus making it look like the connection hanged. Problem is solved now