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IP address

IPv4

Special IPs:

  • 0.0.0.0

    Non-routable meta address.

    Used to designate Invalid, unknown targets.

    Also used as host to listen up to all public IPs. (flask run -h 0.0.0.0)

  • 127.0.0.1

    one of loopback address (starting from 127) used to establish connection with the same machine.

  • localhost

    Usually point to 127.0.0.1

    Defined in /etc/hosts:

    127.0.0.1 localhost
    ::1 localhost // ipv6
    

IPv6

128bit

NAT (Network Address Translation)

用于缓解IPv4不足,指的是路由器自动修改IP报文实现LAN/WAN之间转换的过程。