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This article mainly introduces how to detect IP address conflicts under Linux, which is very detailed and has a certain reference value. Interested friends must read it!

If two users in the same local area network use the same IP address at the same time, or one user has already obtained an IP address through DHCP, and other users have manually assigned the same IP address, this will cause IP address conflicts and make it impossible for one of the users to use the network normally.

Arping command

The arping command is a tool for sending arp requests to an adjacent host. Arping uses arp packets to check the hardware address on the device through the ping command. Be able to test whether an ip address is already in use on the network, and be able to obtain more device information. The function is similar to ping

The arping command is a tool for sending ARP requests to an adjacent host, checking the hardware address on the device through the ARP response message. It can test whether an IP address is already in use on the network, and can obtain more device information. This function is similar to the ping command.

Ping that address on your computer, and then reply to the source mac address of the ping packet.

Arping command options:

-b: used to send Ethernet broadcast frames (FFFFFFFFFFFF). Arping starts with a broadcast address and uses an unicast address when it receives a response. -q:quiet output does not display any information;-f: exits after receiving the first response message;-timeout: sets a timeout in seconds. Exit if the arping does not receive a full response at the specified time;-c count: indicates that the specified number of ARP request packets are sent and then stopped. If the deadline option is specified, arping waits for the same number of arp response packets until it times out;-s source: sets the value of the SPA field in arp packets sent by arping. If empty, proceed as follows, set to 0.0.0.0 in DAD mode (collision address detection), and destination address in Unsolicited ARP mode (Gratutious ARP), otherwise derived from the routing table;-I interface: sets the network interface used by ping. IP address conflict detection

On the host with the problem, you can use the "arping-I ethN x.x.x.x" command (where x.x.x.x is the IP address of this interface) to detect address conflicts. If there is no output, there is no conflict with this IP address. If there is a conflict, the command displays the MAC address used by the conflicting IP address.

Eg1:

For example, the ip address of my win7 system is 192.168.23.44.

I entered ipconfig/all on the cmd command to query my current mac address

To view the reply to the current reply on another linux environment indicates that there is no ip conflict problem from the corresponding mac reply.

Eg2:

Arping 192.168.1.X from 192.168.X.X eth0 can see the mac address of the reply from 192.168.1.X. If the current mac address does not match the mac you set, then the current ip address conflicts.

The above is all the contents of the article "how to detect IP address conflicts under Linux". Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

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