[linux] Linux blocks IP addresses and refuses to specify IP addresses and CIDR segment methods

Block IP

The command for a single IP is:
iptables -I INPUT -s 211.1.0.0 -j DROP

The command to block the IP segment is
iptables -I INPUT -s 211.1.0.0/16 -j DROP
iptables -I INPUT -s 211.2.0.0/16 -j DROP
iptables -I INPUT -s 211.3.0.0/16 -j DROP

The order to seal the entire paragraph is:
iptables -I INPUT -s 211.0.0.0/8 -j DROP

The order to seal a few paragraphs is
iptables -I INPUT -s 61.37.80.0/24 -j DROP
iptables -I INPUT -s 61.37.81.0/24 -j DROP

The server starts from running
There are three ways:
1. Add it to /etc/rc.local
2. iptables-save >;/etc/sysconfig/iptables can put your current iptables rules in /etc/sysconfig/iptables, and the system will automatically execute them when iptables is started.
3. Service iptables save can also put your current iptables rules in /etc/sysconfig/iptables, and the system will automatically execute them when you start iptables.
The latter two are better for this, generally iptables services will be started before network services, which is more secure

Unblocking:

iptables -L INPUT

iptables -L --line-numbers then iptables -D INPUT serial number