README
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Address Rewrite Rules Demo
This demo shows how the extended AddressRewriteRule feature in pion/ice rewrites addresses for a multi-homed host. It runs a small client that gathers host, srflx, UDP, and TCP candidates so you can see exactly what each rule produces.
The included docker-compose.yml places one container on multiple host networks, similar to setups like the Glimesh broadcast box. The demo covers:
- Multiple host networks with fixed public IPs for each interface.
- Host and server-reflexive addresses from deterministic srflx pools.
- Scoped rules that only rewrite specific CIDRs, with a global fallback for others.
- TCP candidates generated by an automatic TCP mux.
- Zero-length External handling: replace+empty drops a candidate, append+empty keeps it (useful for deny/allow layering).
Scenarios
| Key | Description |
|---|---|
multi-net |
Two host networks with distinct public IPs plus a global fallback. |
srflx |
A srflx pool (two addresses) plus a host mapping for the service interface. |
scoped |
A CIDR-scoped rule that overrides the global mapping only for matching IPs. |
iface |
Interface-scoped host rewrite; only matching NICs are rewritten. |
The client prints local interfaces and each gathered candidate. A nil candidate marks the end of the scenario.
Docker Compose Topology
The service nat-demo attaches to three bridge networks:
| Network | Subnet | Purpose |
|---|---|---|
lan_blue |
10.10.0.0/24 | First host interface |
lan_green |
10.20.0.0/24 | Second host interface |
lan_service |
10.30.0.0/24 | Shared service leg |
Run everything with:
docker compose up --build nat-demo
Configuration Variables
All mappings come from environment variables so you can match your own network. The important ones are defined in docker-compose.yml:
NAT_DEMO_BLUE_LOCAL/NAT_DEMO_BLUE_PUBLICNAT_DEMO_BLUE_IFACE(defaulteth0)NAT_DEMO_GREEN_LOCAL/NAT_DEMO_GREEN_PUBLICNAT_DEMO_GREEN_IFACE(defaulteth1)NAT_DEMO_GLOBAL_HOST_FALLBACKNAT_DEMO_SERVICE_LOCAL/NAT_DEMO_SERVICE_HOST_PUBLICNAT_DEMO_SCOPED_PUBLIC/NAT_DEMO_SCOPED_CIDRNAT_DEMO_SRFLX_PRIMARY/NAT_DEMO_SRFLX_SECONDARYNAT_DEMO_DROP_LAN(optional) — set to1to drop LAN host candidates via a replace+empty rule.
Override any value with docker compose run -e VAR=... nat-demo.
Documentation
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Overview ¶
Package main provides a simple CLI that prints the host and srflx addresses produced by different address rewrite (1:1) rule configurations. It is designed to be run inside the accompanying docker-compose topology so that each scenario can demonstrate how multi-homed hosts, srflx pools, CIDR scoping, and TCP muxing interact with the new rules.
Source Files