Stable SSH

It keeps the SSH connection alive even if the laptop is closed, the network is switched, or the communication is not stability.

Features

• Switching between Wifi/Priority is seamless.
• Resistant to long communication breaks. (e.g., client terminal sleep)
  • Encap SSH with quic to increase stability.
  • There is an internal buffer to retry and retransmit connections.

Similar Softwares

It is influenced by the following software, but differs in some respects.

• quicssh-rs
  • The point to encap ssh with quic is the same.
  • Because quicssh-rs has no internal buffer or retry function, there is no regime for long communication breaks (e.g., client sleep).
• mosh
  • The same internal buffer and retry function are retained, making it tolerant of long communication breaks.
  • It is not ssh, so port forwarding, file transfer, vscode remote, etc. are not available.

Usage

Installation

For Mac(homebrew)

brew install hrntknr/tap/stablessh

For other platforms

cargo install stablessh

Client config (sshconfig)

Host target
  Port 2222
  ProxyCommand stablessh client %h:%p

VSCode config (For remote ssh)

"remote.SSH.useLocalServer": false,

Server daemon (systemd)

[Unit]
Description=stablessh Daemon

[Service]
Type=simple
ExecStart=/usr/local/bin/stablessh server
[Install]
WantedBy=multi-user.target

Ctl command

> $ stablessh ctl conn list
 id       | name | last_active | pkt_buf
----------+------+-------------+---------
 d01c1bbe | mba  | in_use      | 0
 aba69f2a | mba  | 6           | 0

> $ stablessh ctl conn kill aba69f2a

> $ stablessh ctl conn list
 id       | name | last_active | pkt_buf
----------+------+-------------+---------
 d01c1bbe | mba  | in_use      | 0

Options

> $ stablessh --help
Usage: stablessh <COMMAND>

Commands:
  server
  client
  ctl
  help    Print this message or the help of the given subcommand(s)

Options:
  -h, --help  Print help

> $ stablessh client --help
Usage: stablessh client [OPTIONS] <TARGET>

Arguments:
  <TARGET>

Options:
  -i, --idle <IDLE>            [default: 3]
  -k, --keepalive <KEEPALIVE>  [default: 1]
  -b, --bufsize <BUFSIZE>      [default: 32]
  -4, --only-ipv4
  -6, --only-ipv6
  -h, --help                   Print help

> $ stablessh server --help
Usage: stablessh server [OPTIONS]

Options:
  -i, --idle <IDLE>                                    [default: 3]
  -k, --keepalive <KEEPALIVE>                          [default: 1]
  -b, --bufsize <BUFSIZE>                              [default: 18]
  -t, --hold-timeout <HOLD_TIMEOUT>                    [default: 604800]
  -c, --hold-collect-interval <HOLD_COLLECT_INTERVAL>  [default: 60]
  -l, --listen <LISTEN>                                [default: 0.0.0.0:2222]
  -f, --forward <FORWARD>                              [default: localhost:22]
  -h, --help                                           Print help

Performance

StableSSH's main target is convenience over performance.
However, in light measurements, the performance was about 50% of that of ssh.

> $ scp ~/100m stablessh:
100m                                                                   100%  100MB   5.4MB/s   00:18

> $ scp ~/100m ssh:
100m                                                                   100%  100MB  11.3MB/s   00:08

About bufsize

bufsize specifies the bit size of the buffer. (upper limit 32)
The default value allows a packet to be buffered for 32-bit space, but it may consume infinite memory.
If memory usage is a concern, try reducing bufsize.

(max memory size) = 4096 * 2 ^ (bufsize) [byte]

bufsize	max memory
4	64K
8	1M
16	256M
18	1G
20	4G
22	16G
24	64G
32	16T