6

If a Red Hat or other Linux host has a conflict with an IP address, is there a way to have it display a warning message on the console or in a log, like Windows and MacOS do?

i.e. my computer has an IP address configured (or received from a DHCP server) but finds another device on the network using the assigned address. Will it log the conflict?

Improve this question

4 Answers 4

Reset to default
18

IP Conflict detection is standardised in RFC 5227. One Linux tool that implements it is IPwatchd, which has a GNOME notification component (ipwatchd-gnotify).

Improve this answer
1
  • +1 - i've never heard about that standard; thanks!
    – pQd
    Apr 28, 2010 at 14:51
10

you can use arpwatch to find out about ip conflicts on ethernet segment you are connected to. it will alert about unseen ip-mac combinations or whenever such association change.

Improve this answer
1
  • It also warns when it sees one box using multiple IPs. False positives ftl :(.
    – sourcejedi
    May 28, 2013 at 16:24
2

You can use the arping command to detect conflicts over a specific IP address: 

arping -I eth0 192.0.2.1

You may find multiple MAC addresses replying for that specific IP address.

Improve this answer
1

I don't know the exact mechanisism of how it does it, but I've seen warnings in CentOS when bringing up a network device along the lines of "Failed to bring up eth0, a device on the network already has this IP".

Improve this answer

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.