Set up a Chromecast from a Linux PC, without an Android or iOS mobile device and without Google Home

castanet.sh

#!/usr/bin/env bash
# castanet.sh: Script to connect a chromecast to a WiFi network.
#
# Allows you to put your Chromecast on WiFi and do Chromecast initial setup
# without using the Google Home app at all, just using a normal Linux computer.
#
# You do need your Chromecast to be on Ethernet, or (untested) to join its setup WiFi
# network with your PC, and you also need to find out its IP yourself with e.g.
# Wireshark.

set -e

if [[ -z "${CHROMECAST_IP}" || -z "${WIFI_SSID}" || -z "${WIFI_PASSWORD}" ]] ; then
    echo 1>&2 "Usage: CHROMECAST_IP=\"XXX\" WIFI_SSID=\"XXX\" WIFI_PASSWORD=\"XXX\" ${0}"
    exit 1
fi

if ! which curl >/dev/null 2>/dev/null ; then
    echo 1>&2 "Install curl to use this script!"
    exit 1
fi

if ! which jq >/dev/null 2>/dev/null ; then
    echo 1>&2 "Install jq to use this script!"
    exit 1
fi

if ! which nodejs >/dev/null 2>/dev/null ; then
    echo 1>&2 "Install nodejs to use this script!"
    exit 1
fi

# Set VERBOSITY=-vvv to see Curl traffic happening
if [[ -z "${VERBOSITY}" ]] ; then
    VERBOSITY=-s
fi

echo "Connecting ${CHROMECAST_IP} to ${WIFI_SSID} with password ${WIFI_PASSWORD}"

# Get the device's public key
INFO_JSON="$(curl ${VERBOSITY} --insecure --tlsv1.2 --tls-max 1.2 https://${CHROMECAST_IP}:8443/setup/eureka_info)"
CHROMECAST_PUBKEY="$(echo "${INFO_JSON}" | jq -r '.public_key')"

# Scan for and find the network we want to get the encryption parameters
curl ${VERBOSITY} --insecure --tlsv1.2 --tls-max 1.2 -X POST https://${CHROMECAST_IP}:8443/setup/scan_wifi
sleep 20
WIFI_JSON="$(curl ${VERBOSITY} --insecure --tlsv1.2 --tls-max 1.2 https://${CHROMECAST_IP}:8443/setup/scan_results)"
WIFI_NETWORK_JSON="$(echo "${WIFI_JSON}" | jq ".[] | select(.ssid == \"${WIFI_SSID}\")")"
WIFI_AUTH_NUMBER="$(echo "${WIFI_NETWORK_JSON}" | jq -r '.wpa_auth')"
WIFI_CIPHER_NUMBER="$(echo "${WIFI_NETWORK_JSON}" | jq -r '.wpa_cipher')"
echo "${WIFI_NETWORK_JSON}"

# Encrypt the password to the device
# Encryption kernel by @thorleifjaocbsen
# See <https://github.com/rithvikvibhu/GHLocalApi/issues/68#issue-766300901>
ENCRYPTED_KEY="$(nodejs <<EOF
let crypto = require('crypto');
let cleartext = "${WIFI_PASSWORD}";
let publicKey = "${CHROMECAST_PUBKEY}";
publicKey = "-----BEGIN RSA PUBLIC KEY-----\n"+publicKey+"\n-----END RSA PUBLIC KEY-----"
const encryptedData = crypto.publicEncrypt({
  key: publicKey,
  padding: crypto.constants.RSA_PKCS1_PADDING,
  // This was in the original thorleifjaocbsen code but seems nonsensical/unneeded and upsest some Nodes
  //oaepHash: "sha256",
}, Buffer.from(cleartext));
console.log(encryptedData.toString("base64"));
EOF
)"

# Generate the command to connect.
CONNECT_COMMAND="{\"ssid\": \"${WIFI_SSID}\", \"wpa_auth\": ${WIFI_AUTH_NUMBER}, \"wpa_cipher\": ${WIFI_CIPHER_NUMBER}, \"enc_passwd\": \"${ENCRYPTED_KEY}\"}"

# And the command to save the connection.
# Include keep_hotspot_until_connected in case we are on the Chromecast's setup hotspot and not Ethernet.
# See <https://github.com/rithvikvibhu/GHLocalApi/issues/88#issuecomment-860538447>
SAVE_COMMAND="{\"keep_hotspot_until_connected\": true}"

# Send the commands
curl ${VERBOSITY} --insecure --tlsv1.2 --tls-max 1.2 -H "content-type: application/json" -d "${CONNECT_COMMAND}" https://${CHROMECAST_IP}:8443/setup/connect_wifi
# Hope this one gets there before it can actually disconnect if we're using the setup hotspot?
# Otherwise we have to use Ethernet or jump over to the target network and find the device again.
# See <http://blog.brokennetwork.ca/2019/05/setting-up-google-chromecast-without.html?m=1> for a script that knows how to swap wifi networks but needs to be ported to use the current API.
curl ${VERBOSITY} --insecure --tlsv1.2 --tls-max 1.2 -H "content-type: application/json" -d "${SAVE_COMMAND}" https://${CHROMECAST_IP}:8443/setup/save_wifi

# To see it working, if you aren't kicked off the hotspot (or if you set the new CHROMECAST_IP in your shell):
#
# curl --insecure --tlsv1.2 --tls-max 1.2 https://${CHROMECAST_IP}:8443/setup/eureka_info | jq .
#
# To list known networks:
#
# curl --insecure --tlsv1.2 --tls-max 1.2 https://${CHROMECAST_IP}:8443/setup/configured_networks | jq .
#
# To forget a newtwork:
#
# curl --insecure --tlsv1.2 --tls-max 1.2 -H "content-type: application/json" -d '{"wpa_id": 0}' https://${CHROMECAST_IP}:8443/setup/forget_wifi
#
# If you leave Ethernet plugged in, the Chromecast will ARP for its WiFi IP on
# Etherenet and drop the WiFi connection! Unplug the Chromecast, and plug it in
# again with no Ethernet, to get it to keep the WiFi connection up!
#
# Set Name and opt out of things:
#
#  curl --insecure --tlsv1.2 --tls-max 1.2 -H "content-type: application/json" -d '{"name": "NovakCast5000", "opt_in": {"crash": false, "stats": false, "opencast": false}}' https://${CHROMECAST_IP}:8443/setup/set_eureka_info

I have a factory-reset chromecast, all it shows is a message telling me to download the app to setup.

I don't know which IP does it have, it doesn't show up on my router (which makes sense since it doesn't know the SSID/password). What am i missing? Is this because uPnP is off in the router?

I used the Chromecast combination power and Ethernet adapter to get the initial connection to set up. If it doesn't have Wifi connection details I think it also creates its own WiFi network and you can connect a computer to that to set it up. If you connect to its access point and look with Wireshark you might see some traffic from the device that ought to reveal its IP.

On Sunday, September 15, 2024, 1000283 ***@***.***> wrote: @1000283 commented on this gist. ________________________________ I have a factory-reset chromecast, all it shows is a message telling me

to download the app to setup.

I don't know which IP does it have, it doesn't show up on my router

(which makes sense since it doesn't know the SSID/password). What am i missing? Is this because uPnP is off in the router?

…

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