Skip to main content

Documentation Index

Fetch the complete documentation index at: https://mintlify.com/damianiglesias/amnesiaOS/llms.txt

Use this file to discover all available pages before exploring further.

AmnesiaOS automatically configures network interfaces at boot using udhcpc — BusyBox’s built-in DHCP client. No manual configuration is needed on networks with a DHCP server. The entire process runs inside /init before the interactive shell is launched, so the network is ready the moment you reach a prompt.

​
How network boot works

1

/init brings up loopback

The init script runs ip link set lo up to enable the loopback interface. This must happen first so that local inter-process communication works correctly before any external interfaces are brought up.
2

Interface discovery

The init script iterates /sys/class/net/* to enumerate all network interfaces present on the system. The loopback interface (lo) is filtered out — only physical and virtual non-loopback interfaces are processed.
3

Interface up

For each discovered interface, the init script runs ip link set <iface> up to bring the link layer up and make it ready to send and receive frames.
4

DHCP request

The init script runs udhcpc for each interface:
udhcpc -i <iface> -n -q -s /usr/share/udhcpc/default.script
FlagMeaning
-i <iface>Bind the DHCP client to this specific interface
-nExit with a non-zero code if no lease is obtained
-qQuit after obtaining the first lease
-sSpecify the hook script to call on lease events
5

Hook script applies config

On a successful lease udhcpc calls default.script with $1 set to bound. The script then applies the IP address, adds the default gateway route, and writes the DNS server list to /etc/resolv.conf.

​
The udhcpc hook script

The file /usr/share/udhcpc/default.script is created during initramfs build time by build-initramfs.sh and is packed into the CPIO archive: 
#!/bin/sh
case "$1" in
    deconfig)
        ip addr flush dev "$interface"
        ;;
    bound|renew)
        ip addr add "$ip"/"${mask:-${subnet:-24}}" dev "$interface"
        if [ -n "$router" ]; then
            ip route add default via "$router" dev "$interface"
        fi
        if [ -n "$dns" ]; then
            > /etc/resolv.conf
            for d in $dns; do
                echo "nameserver $d" >> /etc/resolv.conf
            done
        fi
        ;;
esac
exit 0
udhcpc exports DHCP lease information as shell environment variables ($interface, $ip, $mask, $subnet, $router, $dns) before invoking the script, so the script can apply them directly with standard ip commands.
/etc/resolv.conf is created as an empty file at initramfs build time (touch /etc/resolv.conf) and populated at boot by the DHCP hook script. This ensures the file always exists, even before a lease is obtained.

​
Hook script actions

EventAction
deconfigFlush all addresses from the interface — called before a new DHCP exchange begins
boundSet IP address and prefix length, add the default gateway route, write DNS servers to /etc/resolv.conf
renewSame as bound — refreshes the lease with updated IP, gateway, and DNS values

​
Manual network configuration

For environments without a DHCP server, configure the network manually after reaching the BusyBox shell: 
# Set a static IP
ip addr add 192.168.1.100/24 dev eth0
ip link set eth0 up
ip route add default via 192.168.1.1
echo "nameserver 1.1.1.1" > /etc/resolv.conf
Replace 192.168.1.100, 192.168.1.1, and eth0 with values appropriate for your network. Multiple nameservers can be added by appending additional nameserver lines to /etc/resolv.conf.
Network configuration is stored in RAM (tmpfs). If you reboot, all network config — including any manual static configuration — is lost and re-applied automatically via DHCP on the next boot.

Build docs developers (and LLMs) love

Get started for freeTalk to us