Files
alknet/docs/architecture/decisions/005-socks5-before-tun.md
glm-5.1 596c89ce24 refactor!: rebrand wraith to alknet
Rename all crates, CLI commands, constants, type names, doc comments,
and documentation from wraith to alknet. Includes wire-protocol changes:
ALPN wraith-ssh -> alknet-ssh, reserved destination prefix wraith- ->
alknet-, SSH auth username wraith -> alknet.
2026-06-05 10:04:32 +00:00

1.9 KiB

ADR-005: SOCKS5 as Primary Interface, TUN as Add-on

Status

Accepted

Context

A "VPN-like" tool needs to route traffic. There are three approaches:

  1. TUN only: Create a TUN interface, route all OS traffic through it. Full VPN experience but requires root.
  2. SOCKS5 only: Local SOCKS5 proxy. Applications configure proxy settings. No root needed but application support varies.
  3. SOCKS5 primary, TUN add-on: SOCKS5 is the core interface. TUN forwards to SOCKS5.

Decision

SOCKS5 is the primary interface. TUN is a separate process that forwards to SOCKS5 (Option 3).

SOCKS5 is the core because:

  • It requires no privileges
  • curl --socks5-hostname works everywhere
  • Browsers, most CLI tools, and many applications support SOCKS5
  • SOCKS5h prevents DNS leaks by resolving names server-side
  • It's the interface that the NAPI wrapper and pubsub adapter build on
  • TUN is only needed for "route all traffic" use cases, which are a subset of users

TUN forwards to SOCKS5 rather than directly to SSH because:

  • The SOCKS5 code already handles TCP connection establishment and bidirectional proxying
  • TUN's job is just IP packet → SOCKS5 connection, not IP packet → SSH channel
  • The alknet-tun binary stays minimal (~200-500 lines)
  • No root code in the core binary

Consequences

  • Positive: Core binary is root-free. TUN functionality is provided by the external tun2proxy tool (ADR-014).
  • Positive: SOCKS5 is testable without TUN — just curl against it.
  • Positive: The TUN approach is validated by tun2proxy, a well-tested existing tool. No custom TUN code to maintain.
  • Negative: VPN-like behavior requires running tun2proxy alongside alknet connect — two processes instead of one integrated binary.
  • Negative: SOCKS5 doesn't capture UDP (except DNS via SOCKS5h). TUN mode via tun2proxy handles this separately.

References