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 servermitmproxy- Interactive HTTPS proxynginx- HTTP and reverse proxyiptables/nftables- Linux firewall for transparent proxyCharles- HTTP proxy/monitortinyproxy- Lightweight proxy
Target Processes
- http-proxy-server.js
- socks5-proxy.js
- transparent-proxy.js
Usage Examples
Squid HTTP Proxy Configuration
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
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
mitmproxy -p 8080 --mode transparent
mitmdump -w traffic.flow
PAC File Example
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