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Aether Serial Bridge or ser2net?

ser2net is a long-standing Linux daemon that does the same basic job as Aether Serial Bridge: it gives each serial port its own TCP port. Both work with AetherSDR's network mode. This page says honestly where each one is the better tool.

Use ser2net when

  • The device needs RFC 2217, meaning telnet COM-port control: the client changes the baud rate and drives DTR/RTS on the real port. RFC 2217 and remote DTR/RTS control are not goals of Aether Serial Bridge, and it doesn't do them. The main case is the SPE Expert amplifiers: AetherSDR drives DTR/RTS over RFC 2217 for remote power-on.
  • The host can't run the bridge. That covers a 32-bit OS (such as 32-bit Raspberry Pi OS), glibc older than 2.35, a host without systemd or with cgroup v1, or an ordinary container. The bridge needs all of these (linux.md). ser2net is packaged by Debian, Ubuntu and Raspberry Pi OS.
  • You already run ser2net and it works. There is no need to switch.
  • You want ser2net's other features. It has many more connection options than this bridge; see its own documentation.

Use Aether Serial Bridge when

  • The serial gear is cabled to a Windows PC. ser2net is a Linux daemon. The bridge runs as a Windows service with a configuration window, and it writes the Windows firewall rules for each port and its allowed clients.
  • You want setup without a config file: a window (Windows, x64 Linux desktop), a terminal interface that works over SSH, or the port commands. Each edit is checked before it is saved.
  • You want the bridge's safety rules:
    • it is raw only, so a binary protocol (ACOM) can't be broken by a wrong telnet setting;
    • DTR and RTS are fixed per port, off by default, and no client can toggle them;
    • a change is applied as one guarded operation, and a failed apply leaves the bridge off rather than running half-applied settings (architecture.md).
  • You want a status view: --status, the window and the TUI show each port's state, the connected client, byte counts and the last error.

Both tools let a new connection take over a port from a stale one: ser2net with kickolduser: true, the bridge always. Neither has a password. Whoever can reach a port controls the device, so bind both to a LAN or VPN address and firewall them.

Quick comparison

Aether Serial Bridge ser2net
Raw TCP yes, always yes (accepter: tcp,...)
Telnet / RFC 2217 (remote baud, DTR, RTS) no (not a goal) yes (accepter: telnet(rfc2217),tcp,...)
Windows yes: service, window, firewall rules no
Linux 64-bit (x64, arm64), glibc 2.35+, systemd with cgroup v2 packaged by the major distributions
Configuration window, terminal interface, command line /etc/ser2net.yaml
Allowed-client list Windows: enforced by the firewall rules it writes. Linux: recorded, not enforced. use your firewall

Running both

You can run both on one machine, as long as each serial port and each TCP port belongs to only one of them. A common setup is the bridge for the Elecraft and ACOM gear, and ser2net for an SPE.

ser2net with this repository

The repository still carries a ready-made ser2net setup for Debian, Raspberry Pi OS and Ubuntu. It is separate from the bridge program.

  • ser2net/ser2net.yaml: an example ser2net 4.x configuration with one block per device. The Elecraft devices are active. ACOM (raw) and SPE (telnet + RFC 2217) are commented out.
  • scripts/install.sh: installs ser2net with apt-get and copies the example configuration to /etc/ser2net.yaml. It backs up an existing file first. It also enables the ser2net service and lists your serial adapters.
git clone https://github.com/AetherSDR/AetherSerialBridge
cd aether-serial-bridge
sudo ./scripts/install.sh          # installs ser2net, drops in the example config, lists your adapters
sudoedit /etc/ser2net.yaml         # set the by-id paths, baud rates and bind address
sudo systemctl restart ser2net
ss -ltn                            # the configured TCP ports should be listening

For each device you use in ser2net.yaml:

  1. Replace the REPLACE-ME path with the adapter's /dev/serial/by-id/... name (ls -l /dev/serial/by-id/). Don't use /dev/ttyUSB0: the numbers can swap after a reboot.
  2. Check that the baud rate matches the device's own setting (devices.md).
  3. Bind to a LAN or VPN address: change accepter: tcp,4001 to accepter: tcp,192.168.1.50,4001. Without an address, ser2net listens on every interface.
Device Example port ser2net mode Why
Elecraft KAT500 4001 raw ASCII protocol
Elecraft KPA500 4002 raw ASCII caret protocol
Elecraft KXPA100 4003 raw ASCII caret protocol
ACOM S-series 4010 raw (required) Telnet mode doubles byte 0xFF, which ACOM's binary protocol uses as data
SPE Expert 4011 telnet + RFC 2217 (required) AetherSDR drives DTR/RTS remotely for power-on

kickolduser: true on every port gives the bridge's behaviour: a new connection replaces the old one, so a client that crashed without closing its socket can't lock the port. The local option on the raw ports tells ser2net to ignore the modem-control lines, so a missing DCD signal doesn't stop the data.

Test a raw port (a KAT500, asking for the firmware version):

printf 'RV;' | nc -w 2 192.168.1.50 4001      # expect a reply like RV02.16;

ser2net logs to the journal: journalctl -u ser2net -f. For firewall examples (ufw, firewalld, nftables), see linux.md.