DHCP Log

RouterOS General
1

Hi everyone,
I am using a RouerBoard RB450G with RouterOS v5.0.
I set up a DHCP Server on interface ether3 and it works fine.
However, when I check the log I notice 2 problems as you can see in the pictures.



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  1. dhcp warning dhcp1 offering lease 10.0.10.69 for 00:23:14:52:B4:B4 to B8:AC:6F:63:03:7C without success

This only happens to one IP and two MAC as above.

  1. DHCP Server deassigned and assigned an IP at a same time.

12:27:20 dhcp1 deassigned 10.0.10.62 from 00:0D:0B:B9:27:01
12:27:20 dhcp1 assigned 10.0.10.62 to 00:0D:0B:B9:27:01

This happens to some IPs and MAC addresses.

  1. An IP is assigned and deassigned many times in a short time.






    Here is the DHCP Server Config

add address-pool=dhcp_pool1 authoritative=after-2sec-delay bootp-support=static disabled=no interface=ether3-local lease-time=2d name=dhcp1

/ip dhcp-server config
set store-leases-disk=5m

/ip dhcp-server network
add address=10.0.0.0/16 dns-server=8.8.8.8,210.245.24.22,203.162.4.1,203.162.4.190,208.67.222.222 gateway=10.0.10.1

Here is the Interface ether3

mac-address=00:0C:42:A2:98:2F master-port=none mtu=1500 name=ether3-local speed=100Mbps
set 3 arp=enabled auto-negotiation=yes bandwidth=unlimited/unlimited disabled=no full-duplex=yes l2mtu=1524


So I hope I can have an explanation about why this happen and how could I fix this.
Thank you very much.

2

I would start by going to the logging settings and enable dhcp debug for better logging. you may have to forward it to a syslog server as it may have too much info for the mikrotik log to show properly.

/system logging
add action=memory disabled=yes prefix=dhcp topics=debug

3

I have the same issue and can’t make support.rif → Couldn’t perform action - not permitted (9)

ROS 5.4

4

Tried the filter rules, but none worked for me.

Not sure how to do code so someone else can translate if they like but here’s what worked for me:

SOLUTION (on 5.4): IP → DHCP Server → Leases → Add new → General=“Pool_Name”, MAC Address=“MAC address of desired blocked”, Server=“Name of DHCP Server failing”, Block access = yes, Address List = Black-list

Hope that helps someone else