awk Command to remove Non IP entries from /etc/hosts and /etc/hosts.deny
We had a script automatically adding malicious IPS to our /etc/hosts.deny file on one of our servers.
The script went awry and ended up putting hundreds of thousands of non ip addresses into the file. There were malicious IP addresses mixed in
I used this awk script to clean it up , and remove all of the non ip addresses, and make the list unique.
awk '/ALL/ && $NF ~ /[0-9.]/' /etc/hosts.deny| sort -n -k2 |uniq > /etc/hosts.deny2
once I inspected the /etc/hosts.deny2 I replaced the original
mv /etc/hosts.deny2 /etc/hosts.deny