NETMODE

This page documents basic NETMODE usage, common preparation steps, and practical examples for switching Lichee-Jack network behavior at runtime.

NETMODE controls how the primary Ethernet interface (end0) behaves, allowing payloads to dynamically act as a client, server, or auto-detecting network device.

Pre NETMODE

Before invoking NETMODE, payloads should ensure the network stack and interface are fully ready. Skipping these checks may lead to race conditions or failed configuration.

Operstate

Wait until the Ethernet interface reports an active operational state.


while [ "$(cat /sys/class/net/end0/operstate)" = "down" ]; do
  sleep 1
done

Systemd

Ensure NetworkManager is fully started before applying any NETMODE changes.


until systemctl -q is-active NetworkManager.service
do
  sleep 1
done

Unified wait helper

This helper combines link state and NetworkManager readiness checks into a single reusable function.


function wait_ifup() {
  LED -c FFFF00 -lds 100000
  while [ "$(cat /sys/class/net/end0/operstate)" = "down" ]; do
    sleep 1
  done
 
  until systemctl -q is-active NetworkManager.service
  do
    sleep 1
  done
}
 
wait_ifup
sleep 0.3
NETMODE DHCP_CLIENT

DHCP_CLIENT

Configures Lichee-Jack as a DHCP client, suitable for plugging into an existing network to obtain an IP address automatically.


function setup() {
 
  LED -c FF00FF
 
  wait_ifup
  sleep 0.3
  NETMODE DHCP_CLIENT
 
  LED -c FFFF00 -lbs 100000 # WAIT DHCP
  while [ -z "$SUBNET" ]; do
    sleep 1 && SUBNET=$(ip addr | grep -i end0 | grep -i inet | grep -E -o "([0-9]{1,3}[\.]){3}[0-9]{1,3}[\/]{1}[0-9]{1,2}")
  done
  GATEWAY_IP=$(ip route show default dev end0 | awk '$1=="default"{for(i=1;i<=NF;i++) if($i=="via") print $(i+1)}')
}

DHCP_SERVER

Sets Lichee-Jack to act as a DHCP server, commonly used for rogue APs, captive environments, or isolated attack networks.

udhcpd config

Example udhcpd configuration bound to end0:

/root/config/udhcpd/netmode-end0.conf


# Sample udhcpd configuration file
start		10.11.22.10
end		10.11.22.254
interface	end0
pidfile	/var/run/udhcpd_netmode-end0.pid
lease_file	/var/lib/misc/udhcpd_netmode-end0.leases
option	subnet	255.255.255.0
opt	router	10.11.22.1
option	lease	864000

setup


function wait_ifup() {
  LED -c FFFF00 -lds 100000
  while [ "$(cat /sys/class/net/end0/operstate)" = "down" ]; do
    sleep 1
  done
 
  until systemctl -q is-active NetworkManager.service
  do
    sleep 1
  done
}
 
wait_ifup
sleep 0.3
NETMODE DHCP_SERVER

leases file

Inspect active DHCP leases:


dumpleases /var/lib/misc/udhcpd_netmode-end0.leases

AUTO

AUTO mode automatically selects DHCP client or server behavior based on link conditions and running services.


function wait_ifup() {
  LED -c FFFF00 -lds 100000
  while [ "$(cat /sys/class/net/end0/operstate)" = "down" ]; do
    sleep 1
  done
 
  until systemctl -q is-active NetworkManager.service
  do
    sleep 1
  done
}
 
wait_ifup
sleep 0.3
NETMODE AUTO
 
if systemctl -q is-active udhcpd@netmode-end0.service
then
  dumpleases /var/lib/misc/udhcpd_netmode-end0.leases
else
  while [ -z "$SUBNET" ]; do
    sleep 1 && SUBNET=$(ip addr | grep -i end0 | grep -i inet | grep -E -o "([0-9]{1,3}[\.]){3}[0-9]{1,3}[\/]{1}[0-9]{1,2}")
  done
  GATEWAY_IP=$(ip route show default dev end0 | awk '$1=="default"{for(i=1;i<=NF;i++) if($i=="via") print $(i+1)}')
fi

STATIC

Forces a static IP configuration using NetworkManager defaults.


function wait_ifup() {
  LED -c FFFF00 -lds 100000
  while [ "$(cat /sys/class/net/end0/operstate)" = "down" ]; do
    sleep 1
  done
 
  until systemctl -q is-active NetworkManager.service
  do
    sleep 1
  done
}
 
wait_ifup
sleep 0.3
NETMODE STATIC

CUSTOM

CUSTOM mode applies a user-defined NetworkManager profile.

/root/config/NetworkManager/system-connections/custom.nmconnection


[connection]
id=static
uuid=<uuid4>
type=ethernet
autoconnect=false
interface-name=end0
 
[ipv4]
address1=172.16.80.1/24
method=manual
 
[ipv6]
addr-gen-mode=stable-privacy
method=auto
never-default=true

Important

Make sure the .nmconnection file permissions are set to 600, or NetworkManager will refuse to load it.