Why isn't my forced MAC address change working (Raspberry Pi)?

I'm working with Raspberry Pi Zeros on a subnet. I bought external Ethernet adapters for each one to connect them to one another. Unfortunately, these ethernet adapters all came with the exact same MAC addresses, making communication between the Pis near impossible.

Because of that I've tried forcing a change to the MAC addresses by editing /etc/systemd/network/00-default.link in each Pi Zero in accordance with the steps outlined in this post. Ultimately, I used the following code:

[Match]
MACAddress=00:e0:4c:53:44:58

[Link]
MACAddress=10:00:00:00:00:11

Note that I used a different new MAC address for each Pi

Unfortunately, after restarting all of my Pi Zeros, none of the MAC addresses updated to the new assigned values. When I check with ifconfig they all had remained the same original values. What am I doing wrong?

Additional info:

ip neighbor show yields the following result:

pi@raspberrypi:~ $ ip neighbor show
192.168.2.37 dev wlan0 lladdr ac:bc:32:87:93:39 DELAY
192.168.3.12 dev enxb827eb9c0ecf lladdr 00:e0:4c:53:44:58 STALE
192.168.3.10 dev enxb827eb9c0ecf lladdr 00:e0:4c:53:44:58 STALE
192.168.3.11 dev enxb827eb9c0ecf lladdr 00:e0:4c:53:44:58 STALE
192.168.2.1 dev wlan0 lladdr 40:c7:29:4e:4d:f8 STALE

ifconfig shows:

eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.3.12  netmask 255.255.255.0  broadcast 192.168.3.255
        inet6 fe80::4db4:2630:6df9:2aeb  prefixlen 64  scopeid 0x20<link>
        ether 00:e0:4c:53:44:58  txqueuelen 1000  (Ethernet)
        RX packets 144  bytes 11482 (11.2 KiB)
        RX errors 1  dropped 0  overruns 0  frame 0
        TX packets 133  bytes 17886 (17.4 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

I've also set a static IP in /etc/dhcpcd.conf like so:

interface eth0
static ip_address=192.168.3.12

lsusb yields the output:

Bus 001 Device 002: ID 0fe6:9700 Kontron (Industrial Computer Source / ICS Advent) DM9601 Fast Ethernet Adapter Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

dmesg yields the output:

pi@raspberrypi:~ $ dmesg
[    0.000000] Booting Linux on physical CPU 0x0
[    0.000000] Linux version 4.14.34+ (dc4@dc4-XPS13-9333) (gcc version 4.9.3 (crosstool-NG crosstool-ng-1.22.0-88-g8460611)) #1110 Mon Apr 16 14:51:42 BST 2018
[    0.000000] CPU: ARMv6-compatible processor [410fb767] revision 7 (ARMv7), cr=00c5387d
[    0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT nonaliasing instruction cache
[    0.000000] OF: fdt: Machine model: Raspberry Pi Zero Rev 1.3
[    0.000000] Memory policy: Data cache writeback
[    0.000000] cma: Reserved 8 MiB at 0x17400000
[    0.000000] On node 0 totalpages: 98304
[    0.000000] free_area_init_node: node 0, pgdat c09be368, node_mem_map d7c8a400
[    0.000000]   Normal zone: 864 pages used for memmap
[    0.000000]   Normal zone: 0 pages reserved
[    0.000000]   Normal zone: 98304 pages, LIFO batch:31
[    0.000000] random: fast init done
[    0.000000] pcpu-alloc: s0 r0 d32768 u32768 alloc=1*32768
[    0.000000] pcpu-alloc: [0] 0 
[    0.000000] Built 1 zonelists, mobility grouping on.  Total pages: 97440
[    0.000000] Kernel command line: bcm2708_fb.fbwidth=656 bcm2708_fb.fbheight=416 bcm2708_fb.fbswap=1 vc_mem.mem_base=0x1ec00000 vc_mem.mem_size=0x20000000  dwc_otg.lpm_enable=0 console=ttyAMA0,115200 console=tty1 root=PARTUUID=89bc1db8-02 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait quiet splash plymouth.ignore-serial-consoles
[    0.000000] PID hash table entries: 2048 (order: 1, 8192 bytes)
[    0.000000] Dentry cache hash table entries: 65536 (order: 6, 262144 bytes)
[    0.000000] Inode-cache hash table entries: 32768 (order: 5, 131072 bytes)
[    0.000000] Memory: 370308K/393216K available (6415K kernel code, 587K rwdata, 1984K rodata, 440K init, 677K bss, 14716K reserved, 8192K cma-reserved)
[    0.000000] Virtual kernel memory layout:
                   vector  : 0xffff0000 - 0xffff1000   (   4 kB)
                   fixmap  : 0xffc00000 - 0xfff00000   (3072 kB)
                   vmalloc : 0xd8800000 - 0xff800000   ( 624 MB)
                   lowmem  : 0xc0000000 - 0xd8000000   ( 384 MB)
                   modules : 0xbf000000 - 0xc0000000   (  16 MB)
                     .text : 0xc0008000 - 0xc064c188   (6417 kB)
                     .init : 0xc08c8000 - 0xc0936000   ( 440 kB)
                     .data : 0xc0936000 - 0xc09c8d10   ( 588 kB)
                      .bss : 0xc09ce65c - 0xc0a77ba4   ( 678 kB)
[    0.000000] SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[    0.000000] ftrace: allocating 24081 entries in 71 pages
[    0.000000] NR_IRQS: 16, nr_irqs: 16, preallocated irqs: 16
[    0.000029] sched_clock: 32 bits at 1000kHz, resolution 1000ns, wraps every 2147483647500ns
[    0.000059] clocksource: timer: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1911260446275 ns
[    0.000144] bcm2835: system timer (irq = 27)
[    0.000696] Console: colour dummy device 80x30
[    0.000722] console [tty1] enabled
[    0.000756] Calibrating delay loop... 697.95 BogoMIPS (lpj=3489792)
[    0.060295] pid_max: default: 32768 minimum: 301
[    0.060783] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[    0.060802] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[    0.062076] Disabling memory control group subsystem
[    0.062236] CPU: Testing write buffer coherency: ok
[    0.063310] Setting up static identity map for 0x8200 - 0x8238
[    0.064507] devtmpfs: initialized
[    0.074273] VFP support v0.3: implementor 41 architecture 1 part 20 variant b rev 5
[    0.074648] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[    0.074676] futex hash table entries: 256 (order: -1, 3072 bytes)
[    0.075995] pinctrl core: initialized pinctrl subsystem
[    0.077312] NET: Registered protocol family 16
[    0.080259] DMA: preallocated 1024 KiB pool for atomic coherent allocations
[    0.086650] hw-breakpoint: found 6 breakpoint and 1 watchpoint registers.
[    0.086666] hw-breakpoint: maximum watchpoint size is 4 bytes.
[    0.086788] Serial: AMBA PL011 UART driver
[    0.089479] bcm2835-mbox 2000b880.mailbox: mailbox enabled
[    0.128920] bcm2835-dma 20007000.dma: DMA legacy API manager at d880d000, dmachans=0x1
[    0.131193] SCSI subsystem initialized
[    0.131424] usbcore: registered new interface driver usbfs
[    0.131522] usbcore: registered new interface driver hub
[    0.131723] usbcore: registered new device driver usb
[    0.140800] raspberrypi-firmware soc:firmware: Attached to firmware from 2018-04-16 18:21
[    0.142844] clocksource: Switched to clocksource timer
[    0.227945] VFS: Disk quotas dquot_6.6.0
[    0.228066] VFS: Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
[    0.228352] FS-Cache: Loaded
[    0.228672] CacheFiles: Loaded
[    0.245507] NET: Registered protocol family 2
[    0.246680] TCP established hash table entries: 4096 (order: 2, 16384 bytes)
[    0.246766] TCP bind hash table entries: 4096 (order: 2, 16384 bytes)
[    0.246860] TCP: Hash tables configured (established 4096 bind 4096)
[    0.247011] UDP hash table entries: 256 (order: 0, 4096 bytes)
[    0.247040] UDP-Lite hash table entries: 256 (order: 0, 4096 bytes)
[    0.247387] NET: Registered protocol family 1
[    0.248079] RPC: Registered named UNIX socket transport module.
[    0.248090] RPC: Registered udp transport module.
[    0.248095] RPC: Registered tcp transport module.
[    0.248100] RPC: Registered tcp NFSv4.1 backchannel transport module.
[    0.250051] hw perfevents: no irqs for PMU, sampling events not supported
[    0.250120] hw perfevents: enabled with armv6_1176 PMU driver, 3 counters available
[    0.253895] workingset: timestamp_bits=14 max_order=17 bucket_order=3
[    0.265615] FS-Cache: Netfs 'nfs' registered for caching
[    0.266895] NFS: Registering the id_resolver key type
[    0.266969] Key type id_resolver registered
[    0.266977] Key type id_legacy registered
[    0.267001] nfs4filelayout_init: NFSv4 File Layout Driver Registering...
[    0.271488] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 251)
[    0.271891] io scheduler noop registered
[    0.271903] io scheduler deadline registered (default)
[    0.272429] io scheduler cfq registered
[    0.272443] io scheduler mq-deadline registered
[    0.272450] io scheduler kyber registered
[    0.274823] BCM2708FB: allocated DMA memory 57500000
[    0.274884] BCM2708FB: allocated DMA channel 0 @ d880d000
[    0.282914] Console: switching to colour frame buffer device 82x26
[    0.290733] bcm2835-rng 20104000.rng: hwrng registered
[    0.290954] vc-mem: phys_addr:0x00000000 mem_base=0x1ec00000 mem_size:0x20000000(512 MiB)
[    0.291937] vc-sm: Videocore shared memory driver
[    0.292521] gpiomem-bcm2835 20200000.gpiomem: Initialised: Registers at 0x20200000
[    0.311056] brd: module loaded
[    0.323056] loop: module loaded
[    0.323077] Loading iSCSI transport class v2.0-870.
[    0.323951] usbcore: registered new interface driver smsc95xx
[    0.323983] dwc_otg: version 3.00a 10-AUG-2012 (platform bus)
[    0.552425] Core Release: 2.80a
[    0.552443] Setting default values for core params
[    0.552481] Finished setting default values for core params
[    0.752794] Using Buffer DMA mode
[    0.752807] Periodic Transfer Interrupt Enhancement - disabled
[    0.752813] Multiprocessor Interrupt Enhancement - disabled
[    0.752824] OTG VER PARAM: 0, OTG VER FLAG: 0
[    0.752959] Dedicated Tx FIFOs mode
[    0.753813] WARN::dwc_otg_hcd_init:1046: FIQ DMA bounce buffers: virt = 0xd7514000 dma = 0x57514000 len=9024
[    0.753842] FIQ FSM acceleration enabled for :
               Non-periodic Split Transactions
               Periodic Split Transactions
               High-Speed Isochronous Endpoints
               Interrupt/Control Split Transaction hack enabled
[    0.753853] dwc_otg: Microframe scheduler enabled
[    0.754022] WARN::hcd_init_fiq:459: FIQ on core 0 at 0xc049913c
[    0.754036] WARN::hcd_init_fiq:460: FIQ ASM at 0xc0499418 length 36
[    0.754064] WARN::hcd_init_fiq:486: MPHI regs_base at 0xd88a5000
[    0.754145] dwc_otg 20980000.usb: DWC OTG Controller
[    0.754209] dwc_otg 20980000.usb: new USB bus registered, assigned bus number 1
[    0.754284] dwc_otg 20980000.usb: irq 56, io mem 0x00000000
[    0.754338] Init: Port Power? op_state=1
[    0.754344] Init: Power Port (0)
[    0.754746] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002
[    0.754763] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[    0.754773] usb usb1: Product: DWC OTG Controller
[    0.754783] usb usb1: Manufacturer: Linux 4.14.34+ dwc_otg_hcd
[    0.754792] usb usb1: SerialNumber: 20980000.usb
[    0.755841] hub 1-0:1.0: USB hub found
[    0.755929] hub 1-0:1.0: 1 port detected
[    0.756906] dwc_otg: FIQ enabled
[    0.756918] dwc_otg: NAK holdoff enabled
[    0.756925] dwc_otg: FIQ split-transaction FSM enabled
[    0.756943] Module dwc_common_port init
[    0.757431] usbcore: registered new interface driver usb-storage
[    0.757870] mousedev: PS/2 mouse device common for all mice
[    0.757928] IR NEC protocol handler initialized
[    0.757937] IR RC5(x/sz) protocol handler initialized
[    0.757942] IR RC6 protocol handler initialized
[    0.757947] IR JVC protocol handler initialized
[    0.757952] IR Sony protocol handler initialized
[    0.757957] IR SANYO protocol handler initialized
[    0.757962] IR Sharp protocol handler initialized
[    0.757967] IR MCE Keyboard/mouse protocol handler initialized
[    0.757971] IR XMP protocol handler initialized
[    0.759220] bcm2835-wdt 20100000.watchdog: Broadcom BCM2835 watchdog timer
[    0.759743] bcm2835-cpufreq: min=700000 max=1000000
[    0.760330] sdhci: Secure Digital Host Controller Interface driver
[    0.760340] sdhci: Copyright(c) Pierre Ossman
[    0.760952] sdhost-bcm2835 20202000.mmc: could not get clk, deferring probe
[    0.761148] sdhci-pltfm: SDHCI platform and OF driver helper
[    0.761864] ledtrig-cpu: registered to indicate activity on CPUs
[    0.762047] hidraw: raw HID events driver (C) Jiri Kosina
[    0.762299] usbcore: registered new interface driver usbhid
[    0.762307] usbhid: USB HID core driver
[    0.763320] vchiq: vchiq_init_state: slot_zero = d7580000, is_master = 0
[    0.765220] [vc_sm_connected_init]: start
[    0.774617] [vc_sm_connected_init]: end - returning 0
[    0.775556] Initializing XFRM netlink socket
[    0.775621] NET: Registered protocol family 17
[    0.775780] Key type dns_resolver registered
[    0.777575] registered taskstats version 1
[    0.785666] uart-pl011 20201000.serial: cts_event_workaround enabled
[    0.785796] 20201000.serial: ttyAMA0 at MMIO 0x20201000 (irq = 81, base_baud = 0) is a PL011 rev2
[    0.785895] console [ttyAMA0] enabled
[    0.789187] sdhost: log_buf @ d7513000 (57513000)
[    0.862919] mmc0: sdhost-bcm2835 loaded - DMA enabled (>1)
[    0.864171] of_cfs_init
[    0.864320] of_cfs_init: OK
[    0.865457] Waiting for root device PARTUUID=89bc1db8-02...
[    0.940799] mmc0: host does not support reading read-only switch, assuming write-enable
[    0.942767] mmc0: Problem switching card into high-speed mode!
[    0.943354] mmc0: new SDHC card at address 0001
[    0.944140] mmcblk0: mmc0:0001 SD16G 7.41 GiB (quirks 0x80000000)
[    0.947065]  mmcblk0: p1 p2
[    0.973489] EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Opts: (null)
[    0.973596] VFS: Mounted root (ext4 filesystem) readonly on device 179:2.
[    0.974137] Indeed it is in host mode hprt0 = 00021501
[    1.049913] devtmpfs: mounted
[    1.052380] Freeing unused kernel memory: 440K
[    1.052389] This architecture does not have kernel memory protection.
[    1.182950] usb 1-1: new full-speed USB device number 2 using dwc_otg
[    1.183259] Indeed it is in host mode hprt0 = 00021501
[    1.424142] usb 1-1: New USB device found, idVendor=0fe6, idProduct=9700
[    1.424164] usb 1-1: New USB device strings: Mfr=0, Product=2, SerialNumber=0
[    1.424175] usb 1-1: Product: USB 2.0 10/100M Ethernet Adaptor
[    2.009745] systemd[1]: System time before build time, advancing clock.
[    2.275793] NET: Registered protocol family 10
[    2.277891] Segment Routing with IPv6
[    2.299784] ip_tables: (C) 2000-2006 Netfilter Core Team
[    2.352077] systemd[1]: systemd 232 running in system mode. (+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD +IDN)
[    2.353490] systemd[1]: Detected architecture arm.
[    2.356390] systemd[1]: Set hostname to <raspberrypi>.
[    2.710763] uart-pl011 20201000.serial: no DMA platform data
[    3.764873] systemd[1]: Set up automount Arbitrary Executable File Formats File System Automount Point.
[    3.766038] systemd[1]: Listening on udev Kernel Socket.
[    3.766790] systemd[1]: Listening on fsck to fsckd communication Socket.
[    3.804670] systemd[1]: Started Forward Password Requests to Wall Directory Watch.
[    3.805743] systemd[1]: Listening on Journal Socket.
[    3.807729] systemd[1]: Created slice System Slice.
[    3.814051] systemd[1]: Mounting RPC Pipe File System...
[    4.008481] i2c /dev entries driver
[    6.022129] EXT4-fs (mmcblk0p2): re-mounted. Opts: (null)
[    6.654041] systemd-journald[80]: Received request to flush runtime journal from PID 1
[    9.630719] snd_bcm2835: module is from the staging directory, the quality is unknown, you have been warned.
[    9.703900] bcm2835_alsa bcm2835_alsa: card created with 8 channels
[   10.945104] dm9601 1-1:1.0 eth0: register 'dm9601' at usb-20980000.usb-1, Davicom DM96xx USB 10/100 Ethernet, 00:e0:4c:53:44:58
[   10.949769] usbcore: registered new interface driver dm9601
[   10.971385] usbcore: registered new interface driver sr9700
[   16.499971] enc28j60 spi0.0: enc28j60 Ethernet driver 1.02 loaded
[   16.537004] enc28j60 spi0.0: enc28j60 chip not found
[   16.537113] enc28j60: probe of spi0.0 failed with error -5
[   17.189760] dm9601 1-1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0xFFFF
[   17.236312] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
[   17.240649] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[   17.276623] dm9601 1-1:1.0 eth0: kevent 4 may have been dropped
[   17.284604] dm9601 1-1:1.0 eth0: kevent 4 may have been dropped
[   17.312928] dm9601 1-1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0xFFFF
[   17.411699] dm9601 1-1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0xFFFF
[   19.120593] random: crng init done
[   19.977363] Adding 102396k swap on /var/swap.  Priority:-2 extents:1 across:102396k SSFS
[   28.390600] usb 1-1: unexpected tiny rx frame
[   31.630396] fuse init (API version 7.26)

Here's my completely unsubstantiated guess before I pass out for the night.

You have more interfaces than just the USB Ethernet adapter, and the * in your .link file also matches more than just the USB adapter. Specifically, it matches the lo loopback device as well.

After networkd has changed the MAC address of the first device it matched (which is probably lo due to having the lowest ifindex), it cannot use the same MAC on any other interface – the kernel refuses this kind of duplicate operation. So your new MAC address cannot be put on eth0 because it is occupied by lo.

To prevent this (assuming this is actually the problem), add additional matches – for example, match by Driver or OriginalName.