How to block incoming Russian IP addresses in the iptables by user defined chain

Too much attack/scanning to the server. Try to block all incoming Russian IP addresses in the iptables.

1. First find generate the ACL list from:
https://www.countryipblocks.net/acl.php It gives me a total # of 24,445 line of ip address range at the time.
2. Replace the iptables string for user-defined chain:

iptables

by

iptables -A chain-Russian-Block



Run the command to make create the chain:

iptables -N chain-Russian-Block
...
iptables -A chain-Russian-Block -s 2.56.24.0/23 -j DROP
iptables -A chain-Russian-Block -s 2.56.26.0/23 -j DROP
iptables -A chain-Russian-Block -s 2.56.88.0/22 -j DROP
...
iptables -A INPUT -j chain-Russian-Block

Check total lines of rules in the chain:

# iptables -S chain-Russian-Block | wc -l
24,445

Save it for reboot.

service netfilter-persistent save