Windows Subsystem for Linux 2 (WSL 2) is a popular environment for coding on Windows. This page covers how to connect to the CBorg API from WSL 2, including fixes for common VPN-related network issues.

Network Access Requirements

The CBorg API is accessible from LBLnet, VPN, and other trusted partner networks.

If you are not on one of these networks, you can authorize your current IP address by logging in to https://api.cborg.lbl.gov/key/manage.

WSL 2 + Cisco VPN: Connectivity Fix

By default, WSL 2 uses a virtual network adapter that is not bridged to the host’s VPN tunnel. This means that when Cisco VPN is active on Windows, your WSL 2 environment may lose access to the internet and internal servers like the CBorg API.

Solution: Enable Mirrored Network Mode (Recommended — requires Windows 11)

If you are on Windows 11 (version 22H2 or higher), you can enable mirrored networking. This makes WSL 2 share the host’s network interfaces directly, so VPN traffic routes correctly.

Step 1. Press Win + R, type %userprofile%, and hit Enter to open your Windows user profile folder.

Step 2. Create or edit a file named .wslconfig in that folder.

Step 3. Add the following lines to .wslconfig:

[wsl2]
networkingMode=mirrored
dnsTunneling=true

Step 4. Restart WSL by opening PowerShell and running:

wsl --shutdown

Step 5. Boot WSL back up. Your scripts should now route through the VPN correctly and be able to reach the CBorg API.

Verifying Your Connection

Once WSL 2 is running, you can verify connectivity to the CBorg API with:

curl https://api.cborg.lbl.gov/

You should receive a JSON response. If you get a connection error, double-check that:

• The VPN is connected on the Windows host
• You have restarted WSL after editing .wslconfig
• Your Windows version is 22H2 or higher (winver in Run dialog)

Forcing IPv4 or IPv6 in Python

Since api.cborg.lbl.gov has both A (IPv4) and AAAA (IPv6) DNS records, Python’s httpx library (used by the OpenAI client) will pick whichever address family it resolves first. If IP authorization is failing, or you need to pin to a specific protocol, you can force the connection to use IPv4 or IPv6 explicitly:

import httpx
from openai import OpenAI

# ---------------------------------------------------------
# Step 1: Choose your transport binding
# ---------------------------------------------------------

# To force IPv4 (A record), bind to the IPv4 wildcard address:
# transport = httpx.HTTPTransport(local_address="0.0.0.0")

# To force IPv6 (AAAA record), bind to the IPv6 wildcard address:
transport = httpx.HTTPTransport(local_address="::")

# ---------------------------------------------------------
# Step 2: Inject the transport into the OpenAI client
# ---------------------------------------------------------

# Create a custom httpx client using the transport you defined
custom_http_client = httpx.Client(transport=transport)

# Pass the custom client to the OpenAI library
client = OpenAI(
    base_url="https://api.cborg.lbl.gov/v1",
    api_key="your-api-key",
    http_client=custom_http_client
)

# ---------------------------------------------------------
# Step 3: Make your request normally
# ---------------------------------------------------------

response = client.chat.completions.create(
    model="your-model-name",
    messages=[{"role": "user", "content": "Testing CBorg API on IPv6!"}]
)

print(response.choices[0].message.content)

Still Having Trouble?

Contact scienceit@lbl.gov or reach out in the CBorg Users Chat group on Google Workspace for assistance.