[CentOS] yum update issue

I am getting this when trying to update a machine: warning: rpmts_HdrFromFdno: V3 DSA signature: NOKEY, key ID 6b8d79e6 public key not available for rsync-2.6.4-1.2.el4.rf.i386.rpm

This brings yum to a halt. Here is my yum.conf: [main] cachedir=/var/cache/yum debuglevel=2 logfile=/var/log/yum.log pkgpolicy=newest distroverpkg=centos-release tolerant=1 exactarch=1 retries=20 obsoletes=1 gpgcheck=1 logfile = /var/log/yum.log

# PUT YOUR REPOS HERE OR IN separate files named file.repo # in /etc/yum.repos.d

[dag] name=Dag RPM Repository for Red Hat Enterprise Linux baseurl=http://apt.sw.be/redhat/el$releasever/en/$basearch/dag gpgcheck=1 enabled=1