Following this tutorial https://www.security-sleuth.com/sleuth-blog/2017/3/6/installing-poison-tap-for-dummies-the-most-complete-guide I am trying to install Poison Tap as part of a school project. However I got stuck at the Configuring your poison tap section of the tutorial.

The DHCP server refuses to start. Running the sudo service isc-dhcp-server start command I get the following error message:

Job for isc-dhcp-server.service failed. See 'systemctl status isc-dhcp-server.service' and 'journalctl -xn' for details.

Then I check the error message privided by systemctl status isc-dhcp-server.service

    pi@raspberrypi:~ $ systemctl status isc-dhcp-server.service
    ● isc-dhcp-server.service - LSB: DHCP server
       Loaded: loaded (/etc/init.d/isc-dhcp-server)
       Active: failed (Result: exit-code) since Sun 2017-04-30 09:29:49 UTC; 1min 10s ago
      Process: 9931 ExecStart=/etc/init.d/isc-dhcp-server start (code=exited, status=1/FAILURE)

Which isn't telling me much(except the service doesn't want to start). So I check to get even more details with sudo journalctl -xn:

pi@raspberrypi:~ $ sudo journalctl -xn
-- Logs begin at Mon 2017-04-10 11:17:01 UTC, end at Sun 2017-04-30 09:35:16 UTC
Apr 30 09:35:06 raspberrypi dhcpd[10105]:
Apr 30 09:35:06 raspberrypi dhcpd[10105]: exiting.
Apr 30 09:35:08 raspberrypi isc-dhcp-server[10097]: Starting ISC DHCP server: dh
Apr 30 09:35:08 raspberrypi isc-dhcp-server[10097]: failed!
Apr 30 09:35:08 raspberrypi systemd[1]: isc-dhcp-server.service: control process
Apr 30 09:35:08 raspberrypi sudo[10076]: pam_unix(sudo:session): session closed
Apr 30 09:35:08 raspberrypi systemd[1]: Failed to start LSB: DHCP server.
-- Subject: Unit isc-dhcp-server.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- Unit isc-dhcp-server.service has failed.
-- The result is failed.
Apr 30 09:35:08 raspberrypi systemd[1]: Unit isc-dhcp-server.service entered fai
Apr 30 09:35:16 raspberrypi sudo[10113]: pi : TTY=pts/0 ; PWD=/home/pi ; USER=ro
Apr 30 09:35:16 raspberrypi sudo[10113]: pam_unix(sudo:session): session opened

And since I am trash at configuring a network I get lost in all of this.

Running ifconfig I get this output:

pi@raspberrypi:~ $ ifconfig
lo        Link encap:Local Loopback
          inet addr:  Mask:
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:136 errors:0 dropped:0 overruns:0 frame:0
          TX packets:136 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1
          RX bytes:11472 (11.2 KiB)  TX bytes:11472 (11.2 KiB)

usb0      Link encap:Ethernet  HWaddr 76:22:25:a8:d2:97
          inet addr:  Bcast:  Mask:
          inet6 addr: fe80::1c81:544b:fc83:9c1b/64 Scope:Link
          RX packets:74409 errors:0 dropped:9 overruns:0 frame:0
          TX packets:13024 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:101146949 (96.4 MiB)  TX bytes:2038369 (1.9 MiB)

My dhcp file looks like this:

pi@raspberrypi:~ $ sudo cat /etc/dhcp/dhcpd.conf
# /etc/dhcp/dhcpd.conf

# notes below
ddns-update-style none;
default-lease-time 600;
max-lease-time 7200;
log-facility local7;

# describe the codes used for injecting static routes
option classless-routes code 121 = array of unsigned integer 8;
option classless-routes-win code 249 = array of unsigned integer 8;

# A netmask of 128 will work across all platforms
# A way to cover /0 is to use a short lease.
# As soon as the lease expires and client sends a
# new DHCPREQUEST, you can DHCPOFFER the other half.
subnet netmask {
        option broadcast-address;
        option routers;
        default-lease-time 600;
        max-lease-time 7200;
        option domain-name "local";
        option domain-name-servers;
# send the routes for both the top and bottom of the IPv4 address space
        option classless-routes 1,0, 1,0,0,1,  1,128, 1,0,0,1;
        option classless-routes-win 1,0, 1,0,0,1,  1,128, 1,0,0,1;


And my interfaces file looks like this:

pi@raspberrypi:~ $ cat /etc/network/interfaces
auto lo

iface lo inet loopback
iface eth0 inet dhcp

allow-hotplug wlan0
auto wlan0

auto usb0
    allow-hotplug usb0
    iface usb0 inet static

What am I missing?

  • A ******* reboot that's what was needed to make this work! Commented Apr 30, 2017 at 11:16

1 Answer 1


you just have to reboot your pi, is that simple.

  • 1
    :))) well can't argue with my own answer Commented May 5, 2017 at 17:06

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