Looks like a firewall problem. Check your firewall settings on the newly installed RedHat box with:

[root@host root]# iptatbles -n -L
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If you don't see something like:

Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination
[download]

then you machine is running a firewall, which might block passive FTP connections. These will require some tuning. For a quick check, you can disable firewall and try to use CPAN shell for some installation. To temporarily switch off the firewall run:

[root@host root]# service iptables stop
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If you machine is on the protected network and you don't need firewall at all, then you can switch also disable iptables service at boottime by running:

[root@host root]# chkconfig --level 0123456 iptables off
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HTH.
perl -e 'print "-- \n Leonid Mamtchenkov\n"'