hss - Hurd Socket Stat

A practical, heuristics-based socket table emulator for GNU/Hurd that mimics modern Linux ss and netstat behavior.

Architectural Motivation

On monolithic kernels like Linux, ss queries a centralized kernel-space socket array via Netlink (sock_diag). GNU/Hurd has no monolithic kernel — the network stack and tasks are isolated user-space translators. A single global "socket-to-PID" lookup table does not exist by design. hss emulates this missing table from user space.

Features

• Non-blocking heuristics: Lightning-fast connection scans using O_NONBLOCK and select() across interfaces
• Low-level Mach/Hurd inspection: Crawls the Mach process server using proc_getallpids and proc_getprocargs
• Zero memory leaks: Explicit vm_deallocate for all Mach page memory
• Fast runtime: Resolves the entire user-space distributed map in ~0.320 seconds
• Compact design: Full functionality in ~210 lines of C
• Dual compiler support: Compiles with both tcc (rapid development) and gcc (production)

Design

The entire implementation fits in ~210 lines of C, built around a simple pipeline:

1. Gather — Candidate ports are collected from three sources in priority order: common services from /etc/services (ports 1–1023 plus curated modern ports), a built-in modern-port list, and optional user ports from ~/.config/.hssrc (one port per line).
2. Deduplicate & sort — A single add_entry() helper inserts each candidate in sorted order while skipping duplicates — no separate merge or sort passes.
3. Probe — Each candidate is tested with a non-blocking connect() and a 2-second select() timeout. Localhost listeners are cross-checked against the machine's ethernet IPs for an ss-style multi-address display.
4. Resolve — Owning processes are identified by crawling the Mach proc server (proc_getallpids / proc_getprocargs) and heuristically matching command lines to ports.

Documentation

Detailed function breakdowns, Mach/Hurd concepts, and code explanations are in docs/index.md.

Sample Output

Netid    State        Local Address:Port             Process
tcp      LISTEN       192.168.86.42:22               users:(("sshd-session",pid=13635),...)
tcp      LISTEN       localhost:8000                 users:(("python3",pid=14434))

Usage

hss [target] [options]

Options

Option	Description
target	Host to scan (default: localhost)
--all-processes	Show all processes for each port
--process-limit=N	Limit processes shown per port (default: 3)

Add extra ports to scan by listing them in ~/.config/.hssrc, one per line.

Examples

# Scan localhost with default settings
hss

# Scan remote host
hss 192.168.1.100

# Show all processes
hss localhost --all-processes

# Limit to 5 processes per port
hss localhost --process-limit=5

Compilation & Build

Dependencies

• libc6-dev (standard C library)
• hurd-dev (Hurd system headers)
• gcc or tcc (compiler)

GCC (Production)

gcc -Wall -Wextra -O2 -o hss hss.c

TCC (Development)

tcc -run hss.c

Debian Package

A standard debian/ directory is included, targeting Architecture: hurd-any.

Build Dependencies (on Debian GNU/Hurd)

sudo apt install build-essential hurd-dev dpkg-dev debhelper

Building

./build.sh

This builds both source and binary packages via dpkg-buildpackage -us -uc and collects the resulting artifacts (.deb, .buildinfo, .changes) into dist/.

License

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.

Author

Mark Robillard Jr (MARKMENTAL)