milkv-duo-internet.sh

#!/bin/bash

set -e

if [[ $EUID -ne 0 ]]; then
  echo "[ERROR] This script must be run as root (use sudo)." >&2
  exit 1
fi

SUBNET="192.168.42."

echo "[INFO] Detecting host IP in subnet $SUBNET using arp -a..."
HOST_IP=$(arp -a | grep "$SUBNET" | awk '{print $2}' | tr -d '()' | head -n1)

if [[ -z "$HOST_IP" ]]; then
  echo "[ERROR] Could not find host IP in subnet $SUBNET." >&2
  exit 1
fi

echo "[INFO] Host IP detected as $HOST_IP"

echo "[INFO] SSH into host ($HOST_IP) to enable IP forwarding and iptables rules..."

ssh root@"$HOST_IP" bash -s <<EOF
  set -e
  echo "[HOST] Enabling IP forwarding..."
  sysctl -w net.ipv4.ip_forward=1 >/dev/null
  if [[ \$(sysctl -n net.ipv4.ip_forward) -ne 1 ]]; then
    echo "[HOST ERROR] Failed to enable IP forwarding." >&2
    exit 1
  fi

  OUT_IF=\$(ip route get 8.8.8.8 2>/dev/null | awk '{print \$5; exit}')
  if [[ -z "\$OUT_IF" ]]; then
    echo "[HOST ERROR] Could not detect outgoing interface." >&2
    exit 1
  fi
  echo "[HOST] Outgoing interface detected: \$OUT_IF"

  echo "[HOST] Setting iptables rules..."
  iptables -P FORWARD ACCEPT
  iptables -t nat -C POSTROUTING -s 192.168.42.0/24 -o "\$OUT_IF" -j MASQUERADE 2>/dev/null \
    || iptables -t nat -A POSTROUTING -s 192.168.42.0/24 -o "\$OUT_IF" -j MASQUERADE

  if ! iptables -t nat -L POSTROUTING -n | grep -q MASQUERADE; then
    echo "[HOST ERROR] iptables MASQUERADE rule was not set correctly." >&2
    exit 1
  fi

  echo "[HOST] IP forwarding and NAT setup complete."
EOF

echo "[INFO] Setting default route on Milk-V Duo to host $HOST_IP..."
ip route replace default via "$HOST_IP"

echo "[INFO] Setting DNS on Milk-V Duo..."
echo "nameserver 8.8.8.8" >> /etc/resolv.conf

echo "[INFO] Testing connectivity from Milk-V Duo..."

if ping -c 2 -W 2 8.8.8.8 >/dev/null; then
  echo "[SUCCESS] Milk-V Duo can reach 8.8.8.8"

  if ping -c 2 -W 2 google.com >/dev/null; then
    echo "[SUCCESS] DNS resolution works (google.com reachable)"
  else
    echo "[WARNING] DNS resolution failed, but IP connectivity works."
  fi
else
  echo "[ERROR] Milk-V Duo cannot reach the internet via host." >&2
  exit 1
fi

Do it on boot

This only applies for alpine version

You can also set the static ip by looking at, but it is different.

https://xyzdims.com/3d-printers/misc-hardware-notes/iot-milk-v-duo-risc-v-esbc-running-linux/#Static_IP_for_Host_with_RNDIS

Setup Mac address

create /opt/milkv/rndis-macs.sh and do chmod +x /opt/milkv/rndis-macs.sh

#!/bin/bash

RNDIS_USB="/tmp/usb/usb_gadget/cvitek/functions/rndis.usb0"
MAC_FILE="/etc/rndis-macs.conf"

generate_random_mac() {
    printf "02:%02x:%02x:%02x:%02x:%02x\n" $((RANDOM%256)) $((RANDOM%256)) $((RANDOM%256)) $((RANDOM%256)) $((RANDOM%256))
}

# check if the MAC address file exists and has exactly two lines
if [[ -f "$MAC_FILE" ]] && [[ $(wc -l < "$MAC_FILE") -eq 2 ]]; then
    # read the two MAC addresses from the file
    IFS=$'\n' read -d '' -r -a macs < "$MAC_FILE"
    dev="${macs[0]}"
    host="${macs[1]}"
    echo "using existing MAC addresses:"
else
    # generate two new MAC addresses and store them in the file
    echo "generating new MAC addresses:"
    dev=$(generate_random_mac)
    host=$(generate_random_mac)
    echo "$dev" > "$MAC_FILE"
    echo "$host" >> "$MAC_FILE"
fi
echo "dev_addr: $dev"
echo "host_addr: $host"
echo "$dev" > "$RNDIS_USB"/dev_addr
echo "$host" > "$RNDIS_USB"/host_addr

Afterwards

Edit /etc/init.d/usb-rndis it should be like this

#!/sbin/openrc-run

start() {
        /opt/milkv/uhubon.sh device
        /opt/milkv/run_usb.sh probe rndis
        /opt/milkv/rndis-macs.sh
        /opt/milkv/run_usb.sh start rndis

        sleep 0.5

        ip addr add 192.168.42.1/24 dev usb0
        ip link set usb0 up
        ip route add default via 192.168.42.2

        sleep 0.5
        count=`ps | grep dnsmasq | grep -v grep | wc -l`
        if [ ${count} -lt 1 ] ;then
          rc-service dnsmasq start
        fi
}

stop () {
        rc-service dnsmasq stop
        ifconfig usb0 down
        /opt/milkv/run_usb.sh stop rndis
}

Edit /etc/dnsmasq.conf so it looks like this

interface=usb0
dhcp-range=192.168.42.2,192.168.42.2,1h
dhcp-option=3
dhcp-option=6

Now to automatically setup internet on boot:

tee /usr/local/bin/milkv-network-setup.sh > /dev/null <<'EOF'
#!/bin/sh

set -e

if [ "$(id -u)" != "0" ]; then
  echo "[ERROR] Must be run as root." >&2
  exit 1
fi

SUBNET="192.168.42."

echo "[INFO] Detecting host IP in subnet $SUBNET using arp -a..."
HOST_IP=$(arp -a | grep "$SUBNET" | awk '{print $2}' | tr -d '()' | head -n1)

if [ -z "$HOST_IP" ]; then
  echo "[ERROR] Could not find host IP in subnet $SUBNET." >&2
  exit 1
fi

echo "[INFO] Host IP detected as $HOST_IP"

echo "[INFO] SSH into host ($HOST_IP) to enable IP forwarding and iptables rules..."
ssh root@"$HOST_IP" sh -s <<EOF2
  set -e
  echo "[HOST] Enabling IP forwarding..."
  sysctl -w net.ipv4.ip_forward=1 >/dev/null

  OUT_IF=\$(ip route get 8.8.8.8 2>/dev/null | awk '{print \$5; exit}')
  if [ -z "\$OUT_IF" ]; then
    echo "[HOST ERROR] Could not detect outgoing interface." >&2
    exit 1
  fi
  echo "[HOST] Outgoing interface detected: \$OUT_IF"

  iptables -P FORWARD ACCEPT
  iptables -t nat -C POSTROUTING -s 192.168.42.0/24 -o "\$OUT_IF" -j MASQUERADE 2>/dev/null || \
  iptables -t nat -A POSTROUTING -s 192.168.42.0/24 -o "\$OUT_IF" -j MASQUERADE

  if ! iptables -t nat -L POSTROUTING -n | grep -q MASQUERADE; then
    echo "[HOST ERROR] iptables MASQUERADE rule was not set correctly." >&2
    exit 1
  fi
  echo "[HOST] IP forwarding and NAT setup complete."
EOF2

echo "[INFO] Setting default route on Milk-V Duo to host $HOST_IP..."
ip route replace default via "$HOST_IP"

echo "[INFO] Setting DNS on Milk-V Duo..."
echo "nameserver 8.8.8.8" >> /etc/resolv.conf

echo "[INFO] Testing connectivity from Milk-V Duo..."

if ping -c 2 -W 2 8.8.8.8 >/dev/null; then
  echo "[SUCCESS] Milk-V Duo can reach 8.8.8.8"
  if ping -c 2 -W 2 google.com >/dev/null; then
    echo "[SUCCESS] DNS resolution works (google.com reachable)"
  else
    echo "[WARNING] DNS resolution failed, but IP connectivity works."
  fi
else
  echo "[ERROR] Milk-V Duo cannot reach the internet via host." >&2
  exit 1
fi
EOF

chmod +x /usr/local/bin/milkv-network-setup.sh

Things to do before:

• run ssh-keygen without a password on the milkv-duo
• copy the public key and place it inside of the host authorized_keys (for the root)
• ensure that iptables is setup correctly.
• run /usr/local/bin/milkv-network-setup.sh to know if it is working correctly

---

2. Create an OpenRC service

Create a file /etc/init.d/milkv-network-setup:

tee /etc/init.d/milkv-network-setup > /dev/null <<'EOF'
#!/sbin/openrc-run

description="Milk-V Duo network setup to configure routing via host"

depend() {
    need net
    after firewall
}

start() {
    ebegin "Running Milk-V network setup"
    /usr/local/bin/milkv-network-setup.sh
    eend $?
}
EOF

chmod +x /etc/init.d/milkv-network-setup

---

3. Enable the service

rc-update add milkv-network-setup default

---

4. Test it now (optional)

rc-service milkv-network-setup start

---

Ensure that the host recognize the milkv-duo via ssh

Example doing ssh-keygen and add the public key to the root

How it works

• The script runs after network is up.
• It sets routing/DNS and configures the host remotely over SSH.
• On reboot, it will automatically run your network setup.

if the hosts reboots:

follow this: https://gist.github.com/eznix86/26f1547fcbfb7a0e599c08b72463fc62

if time is an issue append the script with:

echo "Syncing time with NTP..."
ntpd -d -q -n -p pool.ntp.org
echo "Time sync completed"