Three issues prevented transparent proxying from working end-to-end:
1. bwrap dropped CAP_NET_ADMIN before exec, so ip tuntap/link commands
failed inside the sandbox. Add --cap-add CAP_NET_ADMIN and
CAP_NET_BIND_SERVICE when transparent proxy is active.
2. tun2socks only offered SOCKS5 no-auth (method 0x00), but many proxies
(e.g. gost) require username/password auth (method 0x02). Pass through
credentials from the proxy URL so tun2socks offers both auth methods.
3. DNS resolution failed because UDP DNS needs SOCKS5 UDP ASSOCIATE which
most proxies don't support. Add --dns flag and DnsBridge that routes
DNS queries from the sandbox through a Unix socket to a host-side DNS
server. Falls back to TCP relay through the tunnel when no --dns is set.
Also brings up loopback interface (ip link set lo up) inside the network
namespace so socat can bind to 127.0.0.1.
Remove the built-in HTTP/SOCKS5 proxy servers and domain allowlist/denylist
system. Instead, use tun2socks with a TUN device inside the network namespace
to transparently route all TCP/UDP traffic through an external SOCKS5 proxy.
This enables truly transparent proxying where any binary (Go, static, etc.)
has its traffic routed through the proxy without needing to respect
HTTP_PROXY/ALL_PROXY environment variables. The external proxy handles its
own filtering.
Key changes:
- NetworkConfig: remove AllowedDomains/DeniedDomains/proxy ports, add ProxyURL
- Delete internal/proxy/, internal/templates/, internal/importer/
- Embed tun2socks binary (downloaded at build time via Makefile)
- Replace LinuxBridge with ProxyBridge (single Unix socket to external proxy)
- Inner script sets up TUN device + tun2socks inside network namespace
- Falls back to env-var proxying when TUN is unavailable
- macOS: best-effort env-var proxying to external SOCKS5 proxy
- CLI: remove --template/import, add --proxy flag
- Feature detection: add ip/tun/tun2socks status to --linux-features
