openssh via. tor on debian

README.md

Setup opensshd and seperate onion service

Features:

• Not leaking your default sshd host keys, reducing the possibility of deanymizing you
• Warns you of missing dependencies (systemd, tor, openssh-server)
• Setups a hidden (aka onion) service and point it to your openssh port
• Starts it automatically
• Shows you public key fingerprint
• Script can be run multiple times, without overriding/changing existing files
• Secure ssh config # FIXME, config needs review
• Configure localhost address, port and onion config via. shell variables

Usage:

git clone https://github.com/norpol/opensshd-tor-easy-setup
sudo ./opensshd-tor-easy-setup/setup_tor_ssh.sh install

More:

setup_tor_ssh.sh help
setup_tor_ssh.sh uninstall
setup_tor_ssh.sh purge

Note:

• It's recommended using a seperate tor-ssh user for your tor connection. See sshd_config
• How to connect to a hidden service

LICENSE

MIT License

Copyright (c) 2018 Phi|eas |ebada

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

setup_tor_ssh.sh

#!/bin/sh
# setup a hidden (aka onion) service and point it to SSH
# can be run multiple times, doesn't override files or configs when run multiple times
# Note: It's recommended using a seperate user.
set -ue

SCRIPT_NAME="${0}"
SCRIPT_DIR="${SCRIPT_NAME%/*}"

_check_deps() {
   grep -qs '^systemd$' /proc/1/comm || { echo "no systemd detected"; exit 1; }
   tor -h >/dev/null || { echo "no tor detected"; exit 1; }
   sshd --help 2>&1 | grep -qs OpenSSH || { echo "No OpenSSH detected"; exit 1; }
}

_mktee() {
  file="${1}"
  content="${2}"

  if ! grep -qs "${content}" "${file}" 2>/dev/null; then
    printf '%s' "Append to ${file}: "
    printf '%s\n' "${content}" | tee -a "${file}"
  else
    echo "${content} in ${file} exists"
  fi
}

_log_cmd() {
   echo "$ ${*}"
   eval "${*}"
}

_mkcp() {
   from="${1}"
   to="${2}"

   mkdir -vp "${to}"
   cp -n "${from}" "${to}"
}

_install() {
   _check_deps
   _mktee /etc/tor/torrc "HiddenServiceDir /var/lib/tor/ssh_hidden_service"
   _mktee /etc/tor/torrc "HiddenServicePort 22 127.0.1.7:22"
   _mkcp ssh-tor.service "/etc/systemd/system/"
   _mkcp sshd_config "/etc/ssh_tor/"

   # Note: I'm not sure if you are supposed generating keys like this,
   # but it's the common way referred
   [ -f "/etc/ssh_tor/ssh_host_ed25519_key" ] || \
      ssh-keygen -N "" -t ed25519 -f /etc/ssh_tor/ssh_host_ed25519_key
   _log_cmd systemctl daemon-reload
   _log_cmd systemctl restart tor
   _log_cmd systemctl restart ssh-tor
   _log_cmd systemctl enable ssh-tor
   fingerprint="$(ssh-keyscan -p 22 -t "ed25519" 127.0.1.7 2>/dev/null)"
   onion_addr="$(cat /var/lib/tor/ssh_hidden_service/hostname)"
   echo "Success; Now you can proceed with https://trac.torproject.org/projects/tor/wiki/doc/TorifyHOWTO/ssh"
   echo "You can add this to your known-hosts:"
   echo "${onion_addr} ${fingerprint#* }"
}

_uninstall() {
   systemctl stop ssh-tor 2>/dev/null || true
   systemctl disable ssh-tor 2>/dev/null || true
   rm -fv /etc/systemd/system/ssh-tor.service
   rm -fv /etc/ssh_tor/sshd_config
   sed -i "/HiddenServiceDir \\/var\\/lib\\/tor\\/ssh_hidden_service/d" /etc/tor/torrc
   sed -i "/HiddenServicePort 22 127.0.1.7:22/d" /etc/tor/torrc
}

_purge() {
   _uninstall
   rm -rfv "/etc/ssh_tor"
   rm -rfv "/var/lib/tor/ssh_hidden_service"
}

_main() {
   cd "${SCRIPT_DIR}"
   case "${1:-}" in
      install) _install
         ;;
      uninstall) _uninstall
         ;;
      purge) _purge
         ;;
      help|-h|--help|-H|*) echo "$0 install|uninstall|purge"; exit 0
   esac
}

# set EVAL=true to source
[ "${EVAL:-0}" = "1" ] || _main "${1:-}"

ssh-tor.service

[Service]
ExecStart=/usr/bin/sshd -D -f /etc/ssh_tor/sshd_config
ExecReload=/bin/kill -HUP $MAINPID
KillMode=process
Restart=always

[Install]
WantedBy=multi-user.target

# This service file runs an SSH daemon that forks for each incoming connection.
# If you prefer to spawn on-demand daemons, use sshd.socket and sshd@.service.

sshd_config

#/etc/tor_ssh/sshd_config
Port 22
ListenAddress 127.0.1.7
HostKey /etc/ssh_tor/ssh_host_ed25519_key
PasswordAuthentication no
AuthenticationMethods publickey
X11Forwarding no
TCPKeepAlive yes
LogLevel VERBOSE

# Allow client to pass locale environment variables
AcceptEnv LANG LC_*

# optional recommendation:
# AllowTcpForwarding no
# ClientAliveInterval 300
# ClientAliveCountMax 0

# Reduce allowed access to explicit user list
#AllowUsers <your tor user>
#AllowGroups ssh-tor