It can realize emergency response disconnection: prevent the access link of this machine to malicious IP
| /etc/host.conf |
Configuration information declared for the parsing library |
| /etc/hostname |
Configure hostname (permanent) |
| /etc/hosts |
Configure ip address mapping |
| /etc/hosts.allow |
Configure ip address whitelist |
| /etc/hosts.deny |
Configure ip address blacklist |
Analyze the execution sequence flow:
1. host.conf file:
order bind,hosts specifies the query order of the host name, here it is stipulated that the dns resolver is used first, and the hosts file is checked only if the resolution cannot be resolved
multi on Specifies whether the host specified in the "/etc/hosts" file can have multiple addresses. A host with multiple IP addresses is generally called a multi-homed host.
nospoof on or off, specifies whether the spoofing of the host name is turned on/off
2. host file: the file responsible for the quick resolution of IP addresses and domain names
Format: IP address hostname/domain name
For example: 1.1.1.1 www.baidu.com
3./etc/resolv.conf：
This file is a configuration file used by the domain name resolver (resolver, a library that resolves IP addresses based on host names), and is also a configuration file for DNS domain name resolution.
Example:
domain centoscn.com declares the domain name of the host
search www.centocn.com www.wgjlb.com Its multiple parameters indicate the domain name query order
nameserver 8.8.8.8 indicates the IP address of the DNS server
nameserver 8.8.4.4
4. hosts.deny and hosts.allow: deny and allow files
These two files are often configured to prohibit or allow ssh and telnet logins, host.allow takes precedence
| ssh allows a single ip |
sshd:1.1.1.1 |
| ssh ip segment |
sshd:1.1.1.0/24 |
| telnet single ip |
in.telnetd:1.1.1.1 |
| telnet ip segment |
in.telnetd:1.1.1. 0/24 |
Restrict all services to this ip *:1.1.1.1 //Edit deny file