Restricting network access using Linux Iptables

Brief introduction:

Iptables is a user-state module, which is mainly configured for rules;

NetFilter is the kernel module, which is responsible for filtering actions.

Instance:

1. Iptables–f
2. Iptables–a input–i lo–j ACCEPT
3. Iptables–a input–s 127.0.0.1–d 127.0.0.1–j ACCEPT
4. Iptables–a input–p ICMP--icmp-type any–j ACCEPT
5. Iptables–a input–p tcp–-dport 80–j ACCEPT
6. Iptables–a input–p tcp–s 114.114.114.114–-sport 53–j ACCEPT
7. Iptables–a input–p udp–s 114.114.114.114–-sport 53–j ACCEPT
8. Iptables–a input–p tcp–s 8.8.8.8–-sport 53–j ACCEPT
9. Iptables–a input–p udp–s 8.8.8.8–-sport 53–j ACCEPT
10. Iptables–a input–p tcp–s x.x.x.x–-sport 22–j ACCEPT
11. Iptables–a input–j DROP
12. Iptables–a forword–j DROP

Attention:

When configuring a firewall policy to prevent yourself from being locked out of the server, you should be aware of the following two points:

1, in the computer room to carry out the operation of personnel;

2. Deploy in a test environment before the formal environment is deployed.

Restricting network access using Linux Iptables