Duplicate relayed unicast DHCP requests



  • Hello all. I experience a similar problem like in https://forum.pfsense.org/index.php?topic=19959.msg102605. I have updated to the 2.3.2 respectively the 2.3.2_1 release and I observe unicast DHCP requests being forwarded on interfaces for which the dhcrelay was configured.

    Example:
    09:20:43.083455 IP xxx.xxx.67.81.68 > xxx.xxx.25.6.67: BOOTP/DHCP, Request from 00:xx:xx:xx:xx:e3, length 300
    09:20:43.083638 IP xxx.xxx.25.1.67 > xxx.xxx.25.6.67: BOOTP/DHCP, Request from 00:xx:xx:xx:xx:e3, length 300
    09:20:43.083644 IP xxx.xxx.25.5.67 > xxx.xxx.25.6.67: BOOTP/DHCP, Request from 00:xx:xx:xx:xx:e3, length 300
    09:20:43.083719 IP xxx.xxx.25.1.67 > xxx.xxx.25.6.67: BOOTP/DHCP, Request from 00:xx:xx:xx:xx:e3, length 300
    09:20:43.083801 IP xxx.xxx.25.4.67 > xxx.xxx.25.6.67: BOOTP/DHCP, Request from 00:xx:xx:xx:xx:e3, length 300
    09:20:52.006764 IP xxx.xxx.67.81.68 > xxx.xxx.25.6.67: BOOTP/DHCP, Request from 00:xx:xx:xx:xx:e3, length 300
    09:20:52.006840 IP xxx.xxx.25.4.67 > xxx.xxx.25.6.67: BOOTP/DHCP, Request from 00:xx:xx:xx:xx:e3, length 300
    09:20:52.006914 IP xxx.xxx.25.1.67 > xxx.xxx.25.6.67: BOOTP/DHCP, Request from 00:xx:xx:xx:xx:e3, length 300
    09:20:52.006955 IP xxx.xxx.25.5.67 > xxx.xxx.25.6.67: BOOTP/DHCP, Request from 00:xx:xx:xx:xx:e3, length 300
    09:20:52.007067 IP xxx.xxx.25.1.67 > xxx.xxx.25.6.67: BOOTP/DHCP, Request from 00:xx:xx:xx:xx:e3, length 300
    09:20:58.093810 IP xxx.xxx.25.6.67 > xxx.xxx.67.81.68: BOOTP/DHCP, Reply, length 338
    09:20:58.099044 IP xxx.xxx.25.6.67 > xxx.xxx.67.81.68: BOOTP/DHCP, Reply, length 338

    Our DHCP server gets spammed with log entries due to the duplicated DHCP requests. I am curious as there are ways to mitigate or to eliminate that behaviour. What I already did was to add the option "-c 1" to the dhcrelay so that the number of duplicated unicast DHCP requests is reduced.