#!/bin/bash
# SPDX-Version: 3.0
# SPDX-CreationInfo: 2025-05-05; WEIDNER, Marc S.; <msw@coresecret.dev>
# SPDX-ExternalRef: GIT https://git.coresecret.dev/msw/CISS.debian.live.builder.git
# SPDX-FileContributor: WEIDNER, Marc S.; Centurion Intelligence Consulting Agency
# SPDX-FileCopyrightText: 2024-2025; WEIDNER, Marc S.; <msw@coresecret.dev>
# SPDX-FileType: SOURCE
# SPDX-License-Identifier: EUPL-1.2 OR LicenseRef-CCLA-1.0
# SPDX-LicenseComment: This file is part of the CISS.debian.installer.secure framework.
# SPDX-PackageName: CISS.debian.live.builder
# SPDX-Security-Contact: security@coresecret.eu

guard_sourcing

#######################################
# SSH hardening via TCP wrapper.
# Globals:
#   ARY_HANDLER_JUMPHOST
#   BASH_SOURCE
#   VAR_WORKDIR
# Arguments:
#   None
# Returns:
#   0: on success
#######################################
hardening_ssh_tcp() {
  printf "\e[95m++++ ++++ ++++ ++++ ++++ ++++ ++ 🧪 %s starting ... \e[0m\n" "${BASH_SOURCE[0]}"

  if ((${#ARY_HANDLER_JUMPHOST[@]} > 0)); then
    declare allowed=""
    cat << 'EOF' >| "${VAR_WORKDIR}/hosts.allow"
# SPDX-Version: 3.0
# SPDX-CreationInfo: 2025-05-05; WEIDNER, Marc S.; <msw@coresecret.dev>
# SPDX-ExternalRef: GIT https://git.coresecret.dev/msw/CISS.debian.live.builder.git
# SPDX-FileContributor: WEIDNER, Marc S.; Centurion Intelligence Consulting Agency
# SPDX-FileCopyrightText: 2024-2025; WEIDNER, Marc S.; <msw@coresecret.dev>
# SPDX-FileType: SOURCE
# SPDX-License-Identifier: EUPL-1.2 OR LicenseRef-CCLA-1.0
# SPDX-LicenseComment: This file is part of the CISS.debian.installer.secure framework.
# SPDX-PackageName: CISS.debian.live.builder
# SPDX-Security-Contact: security@coresecret.eu

# /etc/hosts.allow: list of hosts that are allowed to access the system.
#                   See the manual pages hosts_access(5) and hosts_options(5).
#
# Example:    ALL: LOCAL @some_netgroup
#             ALL: .foobar.edu EXCEPT terminalserver.foobar.edu
#
# If you're going to protect the portmapper use the name "rpcbind" for the
# daemon name. See rpcbind(8) and rpc.mountd(8) for further information.
#

EOF

    allowed=$(echo "${ARY_HANDLER_JUMPHOST[*]}" | tr '\n' ' ')
    printf 'sshd: %s\n\n# vim: number et ts=2 sw=2 sts=2 ai tw=128 ft=conf\n' "${allowed}" >> "${VAR_WORKDIR}/hosts.allow"

    cat << 'EOF' >| "${VAR_WORKDIR}/hosts.deny"
# SPDX-Version: 3.0
# SPDX-CreationInfo: 2025-05-05; WEIDNER, Marc S.; <msw@coresecret.dev>
# SPDX-ExternalRef: GIT https://git.coresecret.dev/msw/CISS.debian.live.builder.git
# SPDX-FileContributor: WEIDNER, Marc S.; Centurion Intelligence Consulting Agency
# SPDX-FileCopyrightText: 2024-2025; WEIDNER, Marc S.; <msw@coresecret.dev>
# SPDX-FileType: SOURCE
# SPDX-License-Identifier: EUPL-1.2 OR LicenseRef-CCLA-1.0
# SPDX-LicenseComment: This file is part of the CISS.debian.installer.secure framework.
# SPDX-PackageName: CISS.debian.live.builder
# SPDX-Security-Contact: security@coresecret.eu

# /etc/hosts.deny: list of hosts that are _not_ allowed to access the system.
#                  See the manual pages hosts_access(5) and hosts_options(5).
#
# Example:    ALL: some.host.name, .some.domain
#             ALL EXCEPT in.fingerd: other.host.name, .other.domain
#
# If you're going to protect the portmapper use the name "rpcbind" for the
# daemon name. See rpcbind(8) and rpc.mountd(8) for further information.
#
# The PARANOID wildcard matches any host whose name does not match its
# address.
#
# You may wish to enable this to ensure any programs that don't
# validate looked-up hostnames still leave understandable logs. In past
# versions of Debian, this has been the default.
# ALL: PARANOID

ALL: ALL

# vim: number et ts=2 sw=2 sts=2 ai tw=128 ft=conf
EOF
  fi

  printf "\e[92m++++ ++++ ++++ ++++ ++++ ++++ ++ ✅ %s successfully applied. \e[0m\n" "${BASH_SOURCE[0]}"

  return 0
}
### Prevents accidental 'unset -f'.
# shellcheck disable=SC2034
readonly -f hardening_ssh_tcp
# vim: number et ts=2 sw=2 sts=2 ai tw=128 ft=sh