[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

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Isa 54:17  No weapon that is formed against thee shall prosper; 
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shalt condemn. This is the heritage of the servants of the LORD, 
and their righteousness is of me, saith the LORD.

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