BebboSSH

WHAT IS THIS?

BebboSSH is an SSH2 implementation for Amiga systems by Stefan "Bebbo"
Franke. This archive is its port to
AROS i386 (the "alt-abiv0" ABI of AROS One).
With it you can log in to an AROS machine from any SSH client, run
commands, and copy files with scp and sftp; the native clients connect
from AROS to other SSH servers. The original 68k version is
comm/net/bebbossh.lha;
the AROS x86_64 build is comm/net/bebbossh.x86_64-aros.lha,
the AROS aarch64 build is comm/net/bebbossh.aarch64-aros.lha.

PROGRAMS

  bebbosshd       SSH2 server: remote commands, SFTP, SCP, TCP port
                  forwarding (direct-tcpip), password and public-key login
  bebbossh        SSH2 client, with -L local port forwarding
  bebboscp        SCP client
  bebbosshkeygen  Ed25519 key generator

Algorithms: curve25519-sha256 key exchange, ssh-ed25519 host and user
keys, aes128-gcm()openssh.com and chacha20-poly1305()openssh.com ciphers.

REQUIREMENTS

- AROS One i386 (ABIv0, "alt-abiv0").
- A configured TCP/IP stack (AROSTCP, bsdsocket.library).
- No extra libraries: the crypto code is linked into each program.

CONTENTS

  BebboSSH/bebbosshd, bebbossh, bebboscp, bebbosshkeygen
  BebboSSH/sshd_config.example, passwd.example
  BebboSSH/README.AROS.txt   install and configuration guide
  BebboSSH/README.md, AROS_PORTING.md, docs/, scripts/
  BebboSSH/COPYING, LICENSE  license texts (GNU GPL v3)
  BebboSSH/SHA256SUMS        checksums of the files above

INSTALLATION

1. Extract the archive to a persistent volume, for example DH0:.
2. In an AROS Shell, create the configuration and a host key:

     cd DH0:BebboSSH
     copy sshd_config.example sshd_config
     copy passwd.example passwd
     bebbosshkeygen -f ssh_host_ed25519_key

3. Edit passwd: one "username password" pair per line. The test/test
   entry of the example is for a first test only; replace it.
4. Start the server:

     stack 262144
     bebbosshd

5. From another machine: ssh username()<address of the AROS machine>

To start the server at boot, add these lines to S:User-Startup:

  Stack 262144
  If EXISTS DH0:BebboSSH/bebbosshd
      Run DH0:BebboSSH/bebbosshd
  EndIf

To call the clients from anywhere, copy bebbossh, bebboscp and
bebbosshkeygen to C:. Keep bebbosshd in its own directory: the example
configuration finds its files through PROGDIR:.

CONFIGURATION

bebbosshd reads ENVARC:ssh/sshd_config if it exists, otherwise
PROGDIR:sshd_config. The main directives of the example:

  Port 22                 TCP port
  ListenAddress 0.0.0.0   address to listen on (0.0.0.0 = all)
  HostKey PROGDIR:ssh_host_ed25519_key
  Passwords PROGDIR:passwd
  HomeDir DH0:            start directory of commands and SFTP
  Stack 262144            stack of command tasks (default 1 MiB)
  DebugLevel 1            log level: 0 none to 8 ultra, or a name such
                          as error or debug
  SendNoop some           keepalive messages to idle sessions
  Ciphers aes128-gcm()openssh.com,chacha20-poly1305()openssh.com
                          without this line only aes128-gcm is offered
  AllowTcpForwarding yes  direct-tcpip forwarding (ssh -L); no refuses it

Command-line options override the file: -p port, -A password file,
-K host key, -H home directory, -v log level (for example -v5).
Public-key login reads ENVARC:.ssh/authorized_keys (OpenSSH format,
one key per line). README.AROS.txt describes every file in detail.

USAGE

From a PC with OpenSSH:

  ssh user()aros-host version
  scp file.txt user()aros-host:DH0:
  sftp user()aros-host

From AROS:

  bebbossh user()host
  bebbossh -i DH0:keys/id_ed25519 user()host command
  bebbossh -L 8080:localhost:80 user()host
  bebboscp localfile user()host:remotefile
  bebbosshkeygen -f DH0:keys/id_ed25519

The first connection to a host asks, in a console window, whether to
trust its key: answer yes. The key is then kept in
ENVARC:.ssh/known_hosts. Without a console (for example in a remote
command) an unknown host is refused. A host whose key differs from the
stored one is always refused with a warning; if the change is
expected, remove its line from known_hosts.

KNOWN LIMITS

- No full interactive PTY programs: the interactive shell runs simple
  commands, and programs that read their input are rejected with exit
  status 2.
- No redirection or pipes (>, <, |) in remote commands.
- A command typed in an interactive session runs inside the server:
  other connections wait until it ends, and Ctrl-C does not stop it.
  Run long commands as "ssh host command", which runs them in a
  separate task.
- A remote command still running after 30 seconds gets a timeout
  notice and exit status 124, but it keeps running until it ends.
- OpenSSH "put -p" sets the file time before it closes the file, and
  AROS updates the date on close, so that time is not kept.
- passwd.example contains a test password: change it.

WHAT IS NEW IN 1.0.6

- Security fixes ported from bebbossh 1.46.1, an unofficial build by
  Matthias Muench: the server accepts only login requests until a
  client has logged in, and a public-key query without a signature no
  longer logs in; packet parsing in the server and in the clients is
  bounded to the received packet; SFTP requests are bounds-checked;
  the Ed25519 code and bebbosshkeygen no longer write out of bounds;
  authentication tags are compared in constant time, and the clients
  wipe their keys on exit. Updating is recommended.
- The clients refuse a host whose key changed, and ask about an
  unknown host only in a console window.
- New sshd_config directive AllowTcpForwarding (default yes).
- Uploads of 2 MiB or more with scp or sftp no longer stop at 2 MiB.

TESTED

On AROS One i386 under QEMU, with the programs of this archive:
OpenSSH ssh, scp and sftp; 100 logins in a row; 80 file transfers
without pauses; two servers at once; connections dropped during
commands; Ctrl-C on an idle server, with a client, during a command
and while a dropped connection's command still runs, each followed
by a restart; uploads up to 16 MiB; the login and host key checks of
this release, AllowTcpForwarding no; the native clients, also on the
AROS console.

SOURCE AND LICENSE

GNU GPL v3 or later (see COPYING). Source of this release:
  https://github.com/kaffeine1/bebbossh-aros/tree/v1.0.6-aros-i386-abiv0
Original BebboSSH: https://franke.ms/git/bebbo/bebbossh
Bug reports: https://github.com/kaffeine1/bebbossh-aros/issues

Port by Michele Dipace <michele.dipace()kaffeine.net>.