Ethernet Gateway

Ethernet Gateway is a standalone, retro-themed server written in Rust that bridges vintage and modern computing. It provides telnet and SSH access to a full-featured gateway with XMODEM file transfer, SSH and telnet proxying, an AI chat client, a text-mode web browser, weather reports, and Hayes-compatible serial modem emulation.

Designed to work with hardware as old as the Commodore 64 and CP/M machines while remaining fully functional on modern ANSI terminals, Ethernet Gateway adapts its display automatically to the capabilities of each connected client.

Download: Pre-built binaries are available on the GitHub Releases page.

sudo apt install -y build-essential pkg-config cmake curl libudev-dev

When launched for the first time, Ethernet Gateway creates a configuration file (egateway.conf) and the transfer/ directory automatically.

$ ./ethernet-gateway
Ethernet Gateway v0.4.0
Author: Ricky Bryce

Created default configuration: egateway.conf
Config: telnet=true, port=2323, security=false, transfer_dir=transfer

Terminal type is auto-detected by examining the byte sent when the user presses backspace.

After terminal detection and optional authentication, the main menu is displayed.

Press the highlighted letter to select a feature. Press H at any menu for context-sensitive help. Press Esc (or ← on PETSCII) to return to the main menu from any submenu.

Upload, download, and manage files on the server using XMODEM, XMODEM-1K, YMODEM, or ZMODEM. The gateway supports the full Forsberg ZMODEM spec including batch sends, batch receives, and ZSKIP.

Press C to change directories. Subdirectories within the configured transfer directory are listed. Enter .. to go up one level. All paths are canonicalized to prevent symlink escapes.

Telnet NVT (RFC 854) reserves byte 0xFF as the IAC command marker and requires bare CR (0x0D) to be sent as CR-NUL. Strict clients (PuTTY / ExtraPuTTY, Tera Term, C-Kermit) follow these rules; many retro clients (IMP8, CCGMS, StrikeTerm, AltairDuino firmware) just blast raw bytes. We can't tell for sure which one you're running, so the default is set from the detected terminal type — ASCII and PETSCII get escaping off, ANSI gets it on. That's right for the overwhelming majority of real-world combinations, but if a transfer fails repeatedly with bad-block / CRC errors, press I in the File Transfer menu to flip it the other way and retry.

Connect to remote SSH servers through Ethernet Gateway. Press S from the main menu.

Per-IP lockout is shared with the telnet server: after 3 failed authentication attempts in 5 minutes, the source IP is blocked for 5 minutes across both protocols.

ANSI escape sequences from the remote server are automatically stripped when connected from a PETSCII or ASCII terminal, ensuring readable output on vintage hardware. The PTY is sized 40×25 for PETSCII and 80×24 for ANSI/ASCII.

Connect to remote telnet servers through Ethernet Gateway. Press T from the main menu.

Conversational AI powered by Groq's llama-3.3-70b-versatile model.

Text-mode web browser supporting HTTP, HTTPS, and Gopher.

Current conditions and 3-day forecast for any US zip code.

Press W from the main menu. Weather data is provided by the Open-Meteo API (free, no API key required). Your last-used zip code is saved for convenience.

Press C from the main menu. Changes are saved to egateway.conf immediately.

Authentication is disabled by default. When disabled, only private/loopback IPs are allowed, and gateway addresses (*.*.*.1) are rejected.

In the telnet menu, Configuration › F File Transfer opens a submenu with the shared transfer directory plus per-protocol pages for X XMODEM, Y YMODEM, and Z ZMODEM. In the GUI, the same fields live under the File Transfer frame's More... popup.

These three protocols share the same xmodem_* config keys because they use the same send/receive code path. The XMODEM and YMODEM settings pages edit the same values; the page calls out the shared-family behavior so operators aren't surprised when editing either page changes the other.

Independent tunables. These values used to be hardcoded constants in the ZMODEM implementation; they now live in egateway.conf so operators can tune them per environment.

The file egateway.conf uses a simple key = value format. Lines beginning with # are comments. The file is auto-created if missing and rewritten to ensure all keys are present.

# Ethernet Gateway Configuration
telnet_enabled = true
telnet_port = 2323
security_enabled = false
username = admin
password = changeme
transfer_dir = transfer
max_sessions = 50
idle_timeout_secs = 900
ssh_enabled = false
ssh_port = 2222
ssh_username = admin
ssh_password = changeme
groq_api_key =
browser_homepage = http://telnetbible.com
weather_zip =
verbose = false
enable_console = true
serial_enabled = false
serial_port =
serial_baud = 9600
serial_databits = 8
serial_parity = none
serial_stopbits = 1
serial_flowcontrol = none
xmodem_negotiation_timeout = 45
xmodem_block_timeout = 20
xmodem_max_retries = 10
xmodem_negotiation_retry_interval = 7
zmodem_negotiation_timeout = 45
zmodem_frame_timeout = 30
zmodem_max_retries = 10
zmodem_negotiation_retry_interval = 5

Optional encrypted access providing the same features as the telnet interface.

The Ed25519 host key is automatically generated on first use. The SSH server has its own username and password, configured separately from the telnet credentials.

Hayes AT-compatible modem emulation on a physical serial port.

Connect vintage computers with serial interfaces to Ethernet Gateway. The emulator accepts standard AT commands and "dials" TCP connections to remote hosts. Enable it in Configuration > Modem Emulator Settings.

Graphical configuration and monitoring window built with egui.

When enable_console = true, the GUI window opens automatically on startup. It provides a retro amber-on-dark theme with real-time server management.

When security is disabled (the default), Ethernet Gateway restricts access to private and loopback IP ranges only:

All file operations are restricted to the configured transfer directory. Filenames are validated to prevent path traversal. Directory changes are canonicalized to prevent symlink escapes.

On Unix, the following files are written with mode 0o600 (owner read/write only) so other local users can't read them:

On Windows, NTFS ACLs are inherited from the parent directory. For multi-user Windows boxes, place the binary in a per-user folder (e.g. under %USERPROFILE%) so the ACL inherits owner-only access.

Subnegotiation (IAC SB … IAC SE) bodies from remote servers are capped at 8 KiB to prevent a malicious peer from exhausting memory by sending a huge SB without a terminating IAC SE. The state machine still resyncs on the eventual terminator so the session isn't corrupted.

If your terminal is detected as the wrong type, the troubleshooting feature (press R from the main menu) diagnoses input issues by showing exactly what bytes your terminal sends.

Enable verbose mode in Configuration > Other Settings to see detailed XMODEM protocol diagnostics. Useful for debugging file transfer issues.

The Ethernet Gateway GUI console in action.