# Episode 179 - Transparent Proxies

{%youtube Y9UjKDu5HwI %}

## Events
- AWS Partner summit this week
- [OpenObservabilityCon & OTel Community Day](https://events.linuxfoundation.org/openobservabilitycon-otel-community-day/)
- [KubeCon NA](https://events.linuxfoundation.org/kubecon-cloudnativecon-north-america/program/cfp/)
- Open Source Summit Korea - Seoul, Korea - November 5, 2025 - CFP is open - deadline June 30, 2025.
- Open Source Summit Japan - Tokyo, Japan - December 8-10, 2025 - CFP is open - deadline August 4, 2025
- Open Compliance Summit - Tokyo, Japan - December 11 & 12, 2025 CFP is open - deadline August 17, 2025

## News
* [Cilium newsletter!](https://cilium.io/newsletter)
* [Optimizing eBPF I/O latency accounting when running 37M IOPS, on 384 CPUs - Tanel Poder Consulting](https://tanelpoder.com/posts/optimizing-ebpf-biolatency-accounting/)

## Transparent Proxies!


### Why?

- Observability (read-only)
- Security (Add encryption)
- Security (block traffic/content filtering)
- Application (re-direct traffic)
- Application (caching)

### Examples

- Squid 🦑 - [https://www.squid-cache.org/](https://www.squid-cache.org/)
- [https://mitmproxy.org/](https://mitmproxy.org/)
- Envoy - [https://www.envoyproxy.io](https://www.envoyproxy.io/docs/envoy/latest/intro/life_of_a_request)

### Getting traffic to a proxy

- iptables

Since we’re configuring a transparent proxy, we need to configure IP forwarding on the system:

`sudo sysctl net.ipv4.ip_forward=1`

Anything going outbound to `80` should be "transparently" redirected to 3128) port of squid

`sudo iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 3128`

For HTTPs we can create a middle cert that we have to accept in the browser (it's not great)

Example: https://dev.to/suntong/squid-proxy-and-ssl-interception-1oa4

- Applications built upon cURL

*libcurl respect environnement variables http_proxy https_proxy*

So this is very simple :

export http_proxy=http://yourproxy.example.com:3128/
export https_proxy=http://yourproxy.example.com:3128/
./my-application

### Example with eBPF