Sentry Answers>Flask>

Get the IP address of a visitor in Flask

Get the IP address of a visitor in Flask

David Y.

The ProblemJump To Solution

How do I get the IP address of a visitor in Flask?

The Solution

The IP address associated with the current request is stored in the Flask Request object’s remote_addr attribute. The following simple application will display the IP address of visitors to the /whatsmyip route:

Click to Copy
from flask import Flask, request app = Flask(__name__) @app.route("/whatsmyip", methods=["GET"]) def whats_my_ip(): return request.remote_addr

However, this will only work if users connect directly to your Flask web server. If it’s running behind a proxy such as NGINX, as is often the case in production environments, remote_addr will always be the local loopback address, From Flask’s perspective, all requests are coming from the proxy.

Fortunately, we can fix this by including some additional code to tell Flask it is behind a proxy. This code will configure our application to assign request.remote_addr from the request’s X-Forwarded-For HTTP header.

Click to Copy
from werkzeug.middleware.proxy_fix import ProxyFix app.wsgi_app = ProxyFix( app.wsgi_app, x_for=1, x_proto=1, x_host=1, x_prefix=1 )

ProxyFix must be called with the exact number of proxies that are in front of the Flask server, or malicious users will be able to spoof their IP addresses by including their own X-Forwarded-For header in their requests.

  • SentryFlask Error Monitoring
  • Community SeriesIdentify, Trace, and Fix Endpoint Regression Issues
  • logo
    Listen to the Syntax Podcast

    Tasty treats for web developers brought to you by Sentry. Get tips and tricks from Wes Bos and Scott Tolinski.


Loved by over 4 million developers and more than 100,000 organizations worldwide, Sentry provides code-level observability to many of the world’s best-known companies like Disney, Peloton, Cloudflare, Eventbrite, Slack, Supercell, and Rockstar Games. Each month we process billions of exceptions from the most popular products on the internet.

© 2024 • Sentry is a registered Trademark
of Functional Software, Inc.