How to disable and enable IP address in CentOS7?

1. Block ip

I haven’t logged into my VPS for a long time. Today I used Xshell to log in and saw the Last Failed Login. After a closer look, I saw an unknown IP trying to crack my VPS. After confirming with my partner that it was not his IP, I decided to fix this ip is blocked.

(Picture 1: An unknown IP tried to log in to my VPS)

CentOS7 command to block ip: iptables

Usage (note case-sensitive):

iptables -I INPUT -s ***.***.***.*** -j DROP

(Figure 2: Usage of iptables blocking IP)

Parameter -I means Insert (add), followed by rules, INPUT means inbound, ***.***.***.*** means the IP to be blocked, DROP means giving up the connection . After successfully executing the command, there will be no prompt. To view the blocked IP list, execute the command:

iptables --list

(Figure 3: Use the list parameter to view the IP addresses blocked by DROP. The blocked IP addresses are below the source)

2. Unblock ip

1. To unblock, replace -I with -D. The premise is that iptables already has this record:

iptables -D INPUT -s ***.***.***.*** -j DROP

2. If you want to clear the blocked IP address, you can enter:

iptables --flush

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