---
title: "Understanding Docker Bridge Networks & Reverse Proxy Topology"
description: "A deep dive into packet routing, iptables NAT tables, and zero-trust Docker container networks."
date: "2026-10-14T00:00:00.000Z"
category: "Docker"
tags: ["Docker", "Networking", "Security", "Linux"]
author: "Mohan"
source: "https://cloud.ondevkit.in/blog/docker-networking-and-reverse-proxies"
---

import Callout from '../../components/mdx/Callout.astro';

When running multi-container stacks in production, exposing host ports directly (`-p 8080:80`) bypasses Linux UFW firewalls via Docker's direct `iptables` manipulation.

Here is how systems architects design isolated bridge networks with secure Traefik edge gateways.

---

## 1. The Docker iptables Trap

When Docker starts with default flags, it prepends rules to the `PREROUTING` and `DOCKER` chains in Linux `netfilter`. This means incoming packets are routed directly to containers **before** reaching standard host firewall rules like `ufw deny 8080`.

<Callout type="warning" title="Security Advisory">
Never expose internal database ports (`5432`, `27017`, `6379`) to host interfaces. Always confine internal services to dedicated user-defined bridge networks.
</Callout>