Question

Send outbound traffic over floating IP

Posted on January 25, 2018
Ubuntu 16.04 Networking
Asked by enewel3

Is it possible to route outbound traffic from a droplet through its floating IP. I.e., make http requests from the droplet that appear to originate from the floating IP?

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Andrew SB

DigitalOcean Employee

• January 25, 2018

Accepted Answer

The short answer is yes. The longer answer is that it depends on the software you are using to make the request. It needs to expose some way of binding to a particular interface. If it does, you’ll need to find what we call the “anchor IP” and use it. The easiest way to find the anchor IP is to inspect your Droplet’s metadata. From the Droplet, run:

curl -s http://169.254.169.254/metadata/v1/interfaces/public/0/anchor_ipv4/address

In my case, it returns 10.10.0.8 If you wanted to make your request with curl you could then use:

curl --interface 10.10.0.8 https://example.com

Or with wget you would use:

wget --bind-address=10.10.0.8 https://example.com

In both cases, example.com would now see the request as coming from my Floating IP not my Droplet’s IP address.

Check out this tutorial for more info on Floating IPs: How To Use Floating IPs on DigitalOcean In particular, see the section on “Droplet Anchor IPs.”

scull7 • January 13, 2020

The following worked for me on ubuntu:

Find the IPv4 gateway anchor:

curl -s http://169.254.169.254/metadata/v1/interfaces/public/0/anchor_ipv4/gateway | xargs route add default gw

If you’re concerned about copy / pasting random things (and you should be); the Floating IP gateway documentation can be found here:

https://developers.digitalocean.com/documentation/metadata/#interface-anchor_ipv4-gateway

hiphipjorge2 • April 23, 2020

It’s crazy that I would think this would be such an essential, important feature of floating ips and yet it’s nearly impossible. After fighting this for about 2 or 3 ours on Ubuntu (Tried pretty much everything here, I could not get it to work).

What I ended up doing is using Squid proxy to handle this. If anyone is interested, here’s a bash script to setup Squid locally (with authentication) and have it route traffic through the floating IP (the line with tcp_outgoing_address $GATEWAY ev is basically where the magic happens).

Hopefully DO can shed some light on how to do this properly soon.