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Strange DHCP error "IP configured at 30:30:30:30:30:30"

The firewall serves the DHCP scope of 254 hosts. There are only 50 to 60 hosts available on the network. Still, somehow my firewall's log says

"DHCP Server: Resources of this pool ran out. Client Info: cid type : cid value : subnet are 1:0x882510176dc7:192.2.2.0"

Any of my PC (the MAC address of the PC is bound with a fixed IP) tries to connect to the network, the Firewall gets 4 error logs in Seq.

PC's details which we are trying to connect is MAC- f4:3b:d8:be:43:fc and Static DHCP lease is 192.2.2.35.

"Log 1 - Assigned IP address 192.2.2.35 to MAC address f4:3b:d8:b6:e8:ba"

"Log 2 - DHCP Server: Received DHCP decline from client, 192.2.2.35, Reported by f4:3b:d8:b6:e8:ba"

"Log 3 - DHCP Server: IP conflict detected, IP configured at 30:30:30:30:30:30"

"Log 4 - DHCP Server: IP conflict detected, IP conflict on Static DHCP lease 192.2.2.35 <-> f4:3b:d8:b6:e8:ba". Now all these 3 log's Source IP is 192.2.2.35.

Help me understand this issue and solve it.

Who is having this MAC 30:30:30:30:30:30.

Category: Firewall Management and Analytics
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Answers

  • BWCBWC Cybersecurity Overlord ✭✭✭

    @dp8 I can't tell you what this is about, but did you checked on Reddit, because it was reported a while back there? One guy reported that the endpoint was trying to get an IP address with multiple interfaces.

    https://www.reddit.com/r/sonicwall/comments/wmpuxn/strange_dhcp_error/

    https://www.reddit.com/r/k12sysadmin/comments/10a7ry9/sonicwall_dhcp_issues/

    I tend to avoid the internal DHCP server in larger environments, because it seems the server is having trouble with the housekeeping. IP Helper to an external DHCP Server solved it for me.

    —Michael@BWc

  • dp8dp8 Newbie ✭

    @BWC Thanks for that. Before posting my Q here I was checking on Reddit and the same pages I visited but that didn't help in my case because it's not 1 PC only, the whole network is unable to get its assigned IP.

    I want to add one more thing here which I tried today, if I am creating another Network (194.5.6.X or any other than 192.2.2.X) this will work fine, with no issue.

    I am wondering about the MAC - 30:30:30:30:30:30, is it a default MAC assigned to any service or what?

    I would give External DHCP Server (DHCP Server on Windows or Linux instead of Sonicwall Firewall) a try if it works well.

    But still, would be happy if there is any solution for the firewall.

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