Error: Package: unbound-libs-1.4.20-2.el5.x86_64 (epel)
Error: Package: ldns-1.6.16-1.el5.x86_64 (epel)
Did you verify these packages were installed? yum list installed | grep libpcap; yum list installed | grep libpython2.4
Keep in mind that using more than one third-party repository can be a very bad thing as one repo may step on the other's toes. If in doubt, remove one, yum clean all && yum update, then yum install <pkgname> again. If you require the use of more than one such repo, you need to look it yum priorities via yum-utils to ensure the weight value of one repo is higher or lower than the other.
When posting a question, it's wise to include information that will assist those trying to assist you.
Ex. I'm running CentOS 6.5 64-bit. I installed repo XYZ-184.108.40.206.5 and ABC-220.127.116.11.7.8. etc.