Ubuntu/RDK Development Proxy Configuration: Automatic Switching and LAN Access

A practical Ubuntu and RDK proxy setup with automatic detection, manual controls, sudo environment inheritance, and troubleshooting for apt, Git, curl, and ROS.

July 16, 2026Updated on August 4, 2026Development,ROS3min read

In Ubuntu and RDK development environments, a proxy often serves apt, Git, curl, ROS packages, and Python dependencies at the same time. A proxy device on the local network may change with the network environment, so fixed shell variables can interfere with offline work, LAN communication, and device debugging.

This article combines an automatic Ubuntu Shell proxy script with the RDK LAN proxy variables into one configuration: the terminal checks the proxy port when it starts and enables the proxy when the port is available. LAN device addresses are added to NO_PROXY so that SSH, ROS nodes, and WebSocket connections stay direct. All host, port, and RDK address examples use placeholders; fill them in for the actual network before deployment.

Ubuntu desktop or an RDK board running Bash.
A proxy service running on another computer or gateway on the same LAN.
A need to let apt, Git, curl, or ROS tools read proxy environment variables.
Frequent switching between a proxied network and a regular network.

First confirm the current shell:

echo "$SHELL"
ps -p "$$" -o comm=

This configuration is written to ~/.bashrc. When an RDK image uses another shell, put the same functions in that shell’s startup file and validate the syntax for that shell.

Variable	Purpose
HTTP_PROXY, HTTPS_PROXY	Provide an HTTP/HTTPS proxy to clients
ALL_PROXY	Provide a SOCKS5 proxy to programs that support the variable
NO_PROXY	Keep local, LAN, and RDK addresses on a direct connection
PROXY_HOST	Address of the LAN proxy device
HTTP_PORT, SOCKS5_PORT	HTTP and SOCKS5 service ports

Setting both uppercase and lowercase variables improves compatibility across programs. Processes launched by apt, Git, curl, and ROS inherit the exported variables from the current shell.

Automatic detection uses nc from netcat-openbsd:

sudo apt update
sudo apt install netcat-openbsd
nc -h

When installing this package for the first time without a proxy, use an accessible package source temporarily or configure the proxy in the system network settings first.

By default, sudo removes some environment variables. Create /etc/sudoers.d/proxy:

sudoedit /etc/sudoers.d/proxy

Write:

Defaults env_keep += "http_proxy https_proxy HTTP_PROXY HTTPS_PROXY all_proxy ALL_PROXY no_proxy NO_PROXY"

Set the owner and permissions, then validate the sudoers syntax:

sudo chown root:root /etc/sudoers.d/proxy
sudo chmod 0440 /etc/sudoers.d/proxy
sudo visudo -c

The expected output includes:

/etc/sudoers: parsed OK
/etc/sudoers.d/proxy: parsed OK

Files under /etc/sudoers.d/ need the root:root owner and 0440 permissions, or sudo may refuse to read them.

Edit ~/.bashrc:

nano ~/.bashrc

Append the following code. Replace PROXY_HOST, HTTP_PORT, SOCKS5_PORT, and RDK_HOST first. Keeping the placeholders temporarily is useful for checking the script structure.

# =========================
# Ubuntu/RDK network proxy
# =========================

PROXY_SCHEME="http"
PROXY_HOST="<PROXY_HOST>"
HTTP_PORT="<HTTP_PORT>"
SOCKS5_PORT="<SOCKS5_PORT>"
RDK_HOST="<RDK_IP>"

# auto: check the proxy port, system proxy, or TUN; port: check only the proxy port
# system: check the system proxy and use the proxy above; tun: check TUN and use the proxy above
# off: do not change proxy variables while reading ~/.bashrc
PROXY_AUTO_MODE="auto"

proxy_configured() {
    [ -n "$PROXY_HOST" ] &&
        [ "$PROXY_HOST" != "<PROXY_HOST>" ] &&
        [ -n "$HTTP_PORT" ] &&
        [ "$HTTP_PORT" != "<HTTP_PORT>" ]
}

proxy_port_available() {
    proxy_configured || return 1
    command -v nc >/dev/null 2>&1 || return 1
    nc -z -w1 "$PROXY_HOST" "$HTTP_PORT" >/dev/null 2>&1
}

proxy_system_enabled() {
    command -v gsettings >/dev/null 2>&1 || return 1
    local mode
    mode=$(gsettings get org.gnome.system.proxy mode 2>/dev/null)
    case "$mode" in
        ""|*none*) return 1 ;;
        *) return 0 ;;
    esac
}

proxy_tun_enabled() {
    command -v ip >/dev/null 2>&1 || return 1
    ip -o link show 2>/dev/null |
        awk -F': ' '{print $2}' |
        cut -d@ -f1 |
        grep -Eq '^(tun|tap|wg|tailscale|zt)'
}

proxy_network_enabled() {
    proxy_port_available || proxy_system_enabled || proxy_tun_enabled
}

proxy_on() {
    if ! proxy_configured; then
        [ "${1:-}" = "--quiet" ] || echo "Please configure PROXY_HOST and HTTP_PORT first."
        return 1
    fi

    export http_proxy="$PROXY_SCHEME://$PROXY_HOST:$HTTP_PORT"
    export https_proxy="$PROXY_SCHEME://$PROXY_HOST:$HTTP_PORT"
    export HTTP_PROXY="$PROXY_SCHEME://$PROXY_HOST:$HTTP_PORT"
    export HTTPS_PROXY="$PROXY_SCHEME://$PROXY_HOST:$HTTP_PORT"

    if [ -n "$SOCKS5_PORT" ] && [ "$SOCKS5_PORT" != "<SOCKS5_PORT>" ]; then
        export all_proxy="socks5h://$PROXY_HOST:$SOCKS5_PORT"
        export ALL_PROXY="socks5h://$PROXY_HOST:$SOCKS5_PORT"
    else
        unset all_proxy ALL_PROXY
    fi

    # NO_PROXY wildcard support depends on the client; RDK_HOST explicitly keeps the device direct.
    export no_proxy="localhost,127.0.0.1,::1,$RDK_HOST,10.*,192.168.*,172.*"
    export NO_PROXY="$no_proxy"

    if [ "${1:-}" != "--quiet" ]; then
        echo "Proxy enabled"
        echo "HTTP proxy: $http_proxy"
        if [ -n "$all_proxy" ]; then
            echo "SOCKS5 proxy: $all_proxy"
        else
            echo "SOCKS5 proxy: disabled"
        fi
    fi
}

proxy_off() {
    unset http_proxy https_proxy HTTP_PROXY HTTPS_PROXY
    unset all_proxy ALL_PROXY no_proxy NO_PROXY
    if [ "${1:-}" != "--quiet" ]; then
        echo "Proxy disabled"
    fi
}

proxy_status() {
    if proxy_system_enabled; then
        echo "System proxy: ON"
    else
        echo "System proxy: OFF"
    fi

    if proxy_tun_enabled; then
        echo "TUN route   : ON"
    else
        echo "TUN route   : OFF"
    fi

    if proxy_port_available; then
        echo "Proxy port  : ON ($PROXY_HOST:$HTTP_PORT)"
    else
        echo "Proxy port  : OFF ($PROXY_HOST:$HTTP_PORT)"
    fi

    if [ -n "$http_proxy" ]; then
        echo "Shell proxy : ON"
        echo "HTTP proxy  : $http_proxy"
        echo "HTTPS proxy : $https_proxy"
        if [ -n "$all_proxy" ]; then
            echo "SOCKS5 proxy: $all_proxy"
        else
            echo "SOCKS5 proxy: disabled"
        fi
    else
        echo "Shell proxy : OFF"
    fi
}

case "$PROXY_AUTO_MODE" in
    auto)
        if proxy_network_enabled && proxy_port_available; then
            proxy_on --quiet
        else
            proxy_off --quiet
        fi
        ;;
    port)
        if proxy_port_available; then
            proxy_on --quiet
        else
            proxy_off --quiet
        fi
        ;;
    system)
        if proxy_system_enabled && proxy_port_available; then
            proxy_on --quiet
        else
            proxy_off --quiet
        fi
        ;;
    tun)
        if proxy_tun_enabled && proxy_port_available; then
            proxy_on --quiet
        else
            proxy_off --quiet
        fi
        ;;
    off)
        ;;
    *)
        echo "Unknown PROXY_AUTO_MODE: $PROXY_AUTO_MODE"
        ;;
esac

Reload the file:

source ~/.bashrc
proxy_status

Manual controls:

proxy_on
proxy_off
proxy_status

proxy_on and proxy_off affect the current shell and its child processes. Opening a new terminal runs the automatic logic again.

env | grep -i proxy

curl -I --max-time 10 https://example.com

Use verbose mode to inspect the CONNECT or SOCKS5 handshake:

curl -vI --max-time 10 https://example.com

sudo env | grep -i proxy
sudo apt update

curl --noproxy '*' -I --max-time 5 http://$RDK_HOST:8000
ssh <RDK_USER>@$RDK_HOST

The device address used by ROS, SSH, the camera page, and the rosbridge WebSocket should be listed in NO_PROXY. Test LAN services with curl –noproxy ‘*’ to isolate proxy rules from connectivity problems.

The proxy mainly serves public dependency downloads:

apt update and apt install retrieve Ubuntu, ROS, or RDK packages.
Git clones and pulls access remote repositories.
curl, wget, and Python package managers access external addresses.

RDK SSH, the camera page, the rosbridge WebSocket, and LAN ROS communication need direct connections. Keeping RDK_HOST and the LAN ranges in NO_PROXY allows the proxy variables to remain active for public requests.

nc only proves that the TCP port accepts a connection. The proxy service still needs the correct protocol. Use http:// for an HTTP proxy and socks5h:// for a SOCKS5 proxy. Check the proxy application’s listening address, port, and access controls.

Check in this order:

proxy_status
sudo env | grep -i proxy
sudo visudo -c
sudo apt -o Debug::Acquire::http=true update

Some apt versions can also use a separate proxy file under /etc/apt/apt.conf.d/. This configuration starts with environment variables so proxy_on and proxy_off control the complete shell setup consistently.

Check that NO_PROXY contains the current RDK IP, hostname, and local network range. Client support for wildcards and CIDR notation varies, so the most reliable approach is to put the exact RDK IP in RDK_HOST.