Sometime it is necessary to block incoming connection or traffic from specific remote host. iptables is administration tool for IPv4 packet filtering and NAT under Linux kernel. Following tip will help you to block attacker or spammers IP address.
How do I block specific incoming ip address?
Following iptable rule will drop incoming connection from host/IP 188.8.131.52:
iptables -A INPUT -s 184.108.40.206 -j DROP iptables -A OUTPUT -d 220.127.116.11 -j DROP
A simple shell script to block lots of IP address
If you have lots of IP address use the following shell script:
A) Create a text file:
# vi /root/ip.blocked
Now append IP address:
# Ip address block file 18.104.22.168 22.214.171.124/24 #126.96.36.199
B) Create a script as follows or add following script line to existing iptables shell script:
BLOCKDB=”/root/ip.blocked” IPS=$(grep -Ev "^#" $BLOCKDB) for i in $IPS do iptables -A INPUT -s $i -j DROP iptables -A OUTPUT -d $i -j DROP done
C) Save and close the file.