There is an update to ethereal for CentOS-3.1
https://rhn.redhat.com/errata/RHSA-2004-136.html referes.
Updated files are :-
updates/i386/RPMS/ethereal-0.10.3-0.30E.1.centos.0.i386.rpm updates/i386/RPMS/ethereal-gnome-0.10.3-0.30E.1.centos.0.i386.rpm updates/i386/SRPMS/ethereal-0.10.3-0.30E.1.centos.0.src.rpm
These are available at http://mirror.centos.org/3.1/ and should be on all mirrors within a few hours.
To update to the latest version 'yum update ethereal' should be sufficient.
Lance