From: Kirk_Rockstein@nowhere.invalid   
      
   On 2023-06-29, Jonathan N. Little  wrote:   
   > Looking for possible causes. The issue is I have one system where the   
   > MAC address has changed for no apparent reason.   
   >   
   > The system is a MSI B75MA-G43 motherboard with on board   
   > RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller with Ubuntu   
   > 22.04.2 LTS desktop. NIC set to DHCP, and I have a Ubuntu server with   
   > local DNS and DHCP server with a LAN pool where I set this client's IP   
   > by matching the MAC address. Straight forward and easy. Been working for   
   > years. For the third time this year the MAC address has changed where   
   > client has the wrong IP breaking my LAN backup system. My OCD nature I   
   > comment changes to record things so server's dhcpd.conf:   
   > ...   
   > # 2023-03-04 Not sure how but Kenny's mac address changed   
   > # 2023-06-23 Dang Kenny's mac changes again   
   > # 2023-06-29 Kenny is back to previous MAC   
   > ...   
   > host kenny {   
   >         #hardware ethernet 1e:2b:ad:33:12:64;   
   >         hardware ethernet d4:3d:7e:b6:ba:a8;   
   >         fixed-address 192.168.57.132;   
   > }   
   >   
   > Those are the two MAC addresses that NIC keeps switching so this morning   
   > if failed recorded by dhcp server lease file /var/lib/dhcp/dhcpd.leases:   
   >   
   > lease 192.168.57.193 {   
   >   starts 4 2023/06/29 09:34:30;   
   >   ends 4 2023/06/29 21:34:30;   
   >   cltt 4 2023/06/29 09:34:30;   
   >   binding state active;   
   >   next binding state free;   
   >   rewind binding state free;   
   >   hardware ethernet 1e:2b:ad:33:12:64; <-NOTE MAC now back to this...   
   >   uid "\001\036+\2553\022d";   
   >   client-hostname "kenny";   
   > }   
   >   
   > Confirmed on client Kenny:   
   > 2: enp3s0:  mtu 1500 qdisc fq_codel   
   > state UP group default qlen 1000   
   >     link/ether 1e:2b:ad:33:12:64 brd ff:ff:ff:ff:ff:ff   
   >     inet 192.168.57.193/24 brd 192.168.57.255 scope global dynamic   
   > noprefixroute enp3s0   
   >        valid_lft 28111sec preferred_lft 28111sec   
   >     inet6 fe80::1feb:64a7:bae6:90da/64 scope link noprefixroute   
   >   
   > Now last Friday when I debugged this ip addr command confirmed at the   
   > time the MAC address was  d4:3d:7e:b6:ba:a8 and not 1e:2b:ad:33:12:64.   
   > Now it is 1e:2b:ad:33:12:64. HOW? I am not spoofing the MAC with   
   > NetworkManger on Kenny(*). This is an Ethernet and not WiFi with   
   > software MAC switching "pseudo-security" measure some employ on Wifi. I   
   > have not recently updated BIOS on this system, so where should I look   
   > for cause? Puzzled.   
   >   
   > (*)Hostname South Park reference: original machine before rebuild from   
   > scratch with new parts was cobbled together from used systems expecting   
   > a "Hey they killed Kenny" moment at any time.   
   >   
      
   Is macchanger installed on that machine?   
   Is it enabled in /etc/default/macchanger?   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)