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raddecen

Member

Registered: 2015-12-19

Posts: 26

macchanger takes a lot of time and dhcpcd picks up my original mac

I tried to use macchanger to randomize the product ID bits of my MAC address but sometimes, it takes a lot of time (40seconds+) to get started and even when it does, dhcpcd picks up my original MAC address.

Here is my /etc/systemd./system/macspoof@enp2s0.service file

[Unit]
Description=macchanger on %I
Wants=network-pre.target
Before=network-pre.target
BindsTo=sys-subsystem-net-devices-%i.device
After=sys-subsystem-net-devices-%i.device

[Service]
ExecStart=/usr/bin/macchanger -e %I
Type=oneshot

[Install]
WantedBy=multi-user.target

I enabled the service and this is the output of systemctl status macspoof@enp2s0.service

● macspoof@enp2s0.service - macchanger on enp2s0
   Loaded: loaded (/etc/systemd/system/macspoof@enp2s0.service; enabled; vendor preset: disabled)
   Active: inactive (dead) since ... 
  Process: 367 ExecStart=/usr/bin/macchanger -e %I (code=exited, status=0/SUCCESS)
 Main PID: 367 (code=exited, status=0/SUCCESS)

systemd[1]: Starting macchanger on enp2s0...
macchanger[367]: Current MAC:  <ORIGINAL MAC> (unknown)
macchanger[367]: Permanent MAC: <ORIGINAL MAC>(unknown)
macchanger[367]: New MAC:     <NEW MAC> (unknown)
systemd[1]: Started macchanger on enp2s0.

This is the output of systemctl status dhcpcd@enp2s0.service

● dhcpcd@enp2s0.service - dhcpcd on enp2s0
   Loaded: loaded (/usr/lib/systemd/system/dhcpcd@.service; enabled; vendor preset: disabled)
   Active: active (running) since ...
  Process: 363 ExecStart=/usr/bin/dhcpcd -q -w %I (code=exited, status=0/SUCCESS)
 Main PID: 386 (dhcpcd)
    Tasks: 1 (limit: 4915)
   CGroup: /system.slice/system-dhcpcd.slice/dhcpcd@enp2s0.service
           └─386 /usr/bin/dhcpcd -q -w enp2s0

dhcpcd[363]: enp2s0: waiting for carrier
dhcpcd[363]: enp2s0: carrier acquired
dhcpcd[363]: DUID <16-DIGIT NUMBER>:<ORIGINAL MAC ADDRESS>
europa dhcpcd[363]: enp2s0: IAID <THE LAST 8 DIGITS OF THE ORIGINAL MAC ADDRESS>
dhcpcd[363]: enp2s0: rebinding lease of 192.168.1.100
dhcpcd[363]: enp2s0: leased 192.168.1.100 for 259200 seconds
dhcpcd[363]: enp2s0: adding route to 192.168.1.0/24
dhcpcd[363]: enp2s0: adding default route via 192.168.1.1
systemd[1]: Started dhcpcd on enp2s0.

Here's my dhcpcd.conf file with the comments removed

hostname
duid
persistent   
option rapid_commit
option domain_name_servers, domain_name, domain_search, host_name
option classless_static_routes
option ntp_servers
option interface_mtu
require dhcp_server_identifier
slaac private
ipv4only     
noarp
noipv4ll
nohook resolv.conf

Is dhcpcd still seeing my original MAC address? If yes, what can I do to make dhcpcd see the randomized MAC address? Why is macchanger taking so much time (I have a SSD) to get activated?

rsmarples

Member

Registered: 2009-05-12

Posts: 287

Re: macchanger takes a lot of time and dhcpcd picks up my original mac

dhcpcd reads the duid in /etc/dhcpcd.duid, if it does not exist then it creates it using the MAC address of a network card in your box if it can.

The DUID is an opaque field - it could be a stream of random bytes really. It just has to uniquely identify the host for the DHCP server so it can be assigned the same address, to avoid pool starvation.