---
name: proxy-server
description: Expert skill for proxy server implementation, configuration, and traffic interception
allowed-tools:
  - Bash
  - Read
  - Write
  - Edit
  - Glob
  - Grep
graph:
  domains: [domain:networking]
  specializations: [specialization:network-programming]
  skillAreas: [skill-area:protocol-design, skill-area:socket-programming]
  roles: [role:backend-engineer, role:sre]
  topics: [topic:circuit-breakers]
---

# Proxy Server Skill

Expert skill for proxy server implementation, configuration, and network traffic interception.

## Capabilities

- **Proxy Configuration**: Configure Squid, mitmproxy, Charles, and nginx proxy
- **HTTP CONNECT Tunneling**: Implement HTTP CONNECT for HTTPS tunneling
- **SOCKS Protocol**: Configure SOCKS4/SOCKS5 proxy servers
- **Transparent Proxying**: Implement transparent proxying with iptables/nftables
- **Traffic Analysis**: Analyze proxy traffic and generate reports
- **Debugging**: Debug proxy connection issues and SSL/TLS interception
- **PAC File Generation**: Generate Proxy Auto-Configuration (PAC) files
- **Caching**: Configure proxy caching strategies

## Tools and Dependencies

- `Squid` - Caching proxy server
- `mitmproxy` - Interactive HTTPS proxy
- `nginx` - HTTP and reverse proxy
- `iptables/nftables` - Linux firewall for transparent proxy
- `Charles` - HTTP proxy/monitor
- `tinyproxy` - Lightweight proxy

## Target Processes

- http-proxy-server.js
- socks5-proxy.js
- transparent-proxy.js

## Usage Examples

### Squid HTTP Proxy Configuration
```squid
http_port 3128
acl localnet src 10.0.0.0/8
http_access allow localnet
cache_dir ufs /var/spool/squid 10000 16 256
```

### Transparent Proxy with iptables
```bash
iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 3128
iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 443 -j REDIRECT --to-port 3129
```

### mitmproxy Interception
```bash
mitmproxy -p 8080 --mode transparent
mitmdump -w traffic.flow
```

### PAC File Example
```javascript
function FindProxyForURL(url, host) {
    if (isPlainHostName(host)) return "DIRECT";
    if (dnsDomainIs(host, ".internal.com")) return "DIRECT";
    return "PROXY proxy.example.com:8080";
}
```

## Quality Gates

- Proxy functionality verified
- SSL/TLS interception working
- Transparent mode operational
- Caching efficiency validated
- Access control tested


---
Source attribution: a5c-ai
Original project: https://github.com/a5c-ai/babysitter
License: MIT
License information: https://opensource.org/license/mit
Original upstream instructions; downloaded from Dave AI.

## Upstream license notice

MIT License

Copyright (c) 2026 Gabriel Moreira

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.



# Dave AI resource metadata

Creator / publisher: a5c-ai
Original project: https://github.com/a5c-ai/babysitter
Attribution basis: Upstream repository explicitly recorded in package mirror path

Fields of work: Development & Engineering, Operations
Roles: Backend Developer, DevOps / SRE, IT Operations
Specialties: Specialty not specified
Tools: Charles, Squid, Iptables, Mitmproxy, Nginx, Tinyproxy
Country applicability: Country not specified
Classification basis: Source catalog labels
Instruction SHA-256: a9fe062bb14563de45596c9bb2ebce9c9ef041e77e6c1affb02178f93a0eaa74