CentOS5 is already out of REHL support line, and the sources offered by system are already invalid.
So we should change it to the Vault-repo.
First:Backup your old sources
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak
Second:Insert Vault Repo as the Base-repo
[base]
name=CentOS-5.11 - Base
failovermethod=priority
baseurl=http://vault.centos.org/5.11/os/$basearch/
gpgcheck=0
gpgkey=http://vault.centos.org/RPM-GPG-KEY-CentOS-5
#released updates
[updates]
name=CentOS-5.11 - Updates
failovermethod=priority
baseurl=http://vault.centos.org/5.11/updates/$basearch/
gpgcheck=0
gpgkey=http://vault.centos.org/RPM-GPG-KEY-CentOS-5
#additional packages that may be useful
[extras]
name=CentOS-5.11 - Extras
failovermethod=priority
baseurl=http://vault.centos.org/5.11/extras/$basearch/
gpgcheck=0
gpgkey=http://vault.centos.org/RPM-GPG-KEY-CentOS-5
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-5.11 - Plus
failovermethod=priority
baseurl=http://vault.centos.org/5.11/centosplus/$basearch/
gpgcheck=0
enabled=0
gpgkey=http://vault.centos.org/RPM-GPG-KEY-CentOS-5
#contrib - packages by Centos Users
[contrib]
name=CentOS-5.11 - Contrib
failovermethod=priority
baseurl=http://vault.centos.org/5.11/contrib/$basearch/
gpgcheck=0
enabled=0
gpgkey=http://vault.centos.org/RPM-GPG-KEY-CentOS-5
Third:Have a Try
yum update
Then you can install software by 'yum' normally
877-SENTRIS
