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CISS.debian.installer/func/cdi_4400_hardening/4420_installation_ssh.sh
2025-08-17 20:48:58 +02:00

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#!/bin/bash
# SPDX-Version: 3.0
# SPDX-CreationInfo: 2025-06-17; WEIDNER, Marc S.; <msw@coresecret.dev>
# SPDX-ExternalRef: GIT https://git.coresecret.dev/msw/CISS.debian.installer.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.installer
# SPDX-Security-Contact: security@coresecret.eu
guard_sourcing
#######################################
# Setup ssh server.
# Globals:
# BASH_REMATCH
# DIR_BAK
# DIR_LOG
# TARGET
# VAR_FINAL_FQDN
# VAR_FINAL_IPV4
# VAR_FINAL_IPV6
# VAR_SETUP_PATH
# ssh_port
# ssh_root_ca
# Arguments:
# None
# Returns:
# 0: on success
#######################################
installation_ssh() {
### Declare Arrays, HashMaps, and Variables.
declare -a ary_user=()
declare -i i=0
declare var_auth="" var_name="" var_ca=""
chroot_exec "${TARGET}" apt-get install -y --no-install-recommends --no-install-suggests ssh
install -D -m 0644 -o root -g root "${VAR_SETUP_PATH}/includes/target/etc/banner" "${TARGET}/etc/"
install -D -m 0644 -o root -g root "${VAR_SETUP_PATH}/includes/target/etc/motd" "${TARGET}/etc/"
do_log "info" "file_only" "4420() Installed SSH '/etc/banner' and '/etc/motd'."
### Only process those for which both *_name and *_authentication_access_ssh are set.
for ((i = 0; i <= VAR_USER_MAX; i++)); do
var_auth="user_user${i}_authentication_access_ssh"
var_name="user_user${i}_name"
if [[ -v "${var_auth}" && -v "${var_name}" && "${!var_auth}" == "true" ]]; then
ary_user+=("${!var_name}")
fi
done
rm -rf "${TARGET}"/etc/ssh/ssh_host_*key*
#shellcheck disable=SC2312
chroot_exec "${TARGET}" ssh-keygen -o -N "" -t ed25519 -f /etc/ssh/ssh_host_ed25519_key -C "root@${VAR_FINAL_FQDN}-$(date -I)"
#shellcheck disable=SC2312
chroot_exec "${TARGET}" ssh-keygen -o -N "" -t rsa -b 4096 -f /etc/ssh/ssh_host_rsa_key -C "root@${VAR_FINAL_FQDN}-$(date -I)"
mkdir -p "${TARGET}/root/.ciss/cdi/backup/etc/ssh"
cp "${TARGET}/etc/ssh/sshd_config" "${TARGET}/root/.ciss/cdi/backup/etc/ssh/sshd_config.bak"
cp "${TARGET}/etc/ssh/ssh_config" "${TARGET}/root/.ciss/cdi/backup/etc/ssh/ssh_config.bak"
rm -f "${TARGET}/etc/ssh/sshd_config"
install -D -m 0600 -o root -g root "${VAR_SETUP_PATH}/includes/target/etc/ssh/sshd_config" "${TARGET}/etc/ssh/sshd_config"
chmod 0600 "${TARGET}/etc/ssh/ssh_config"
insert_comments "${TARGET}/etc/ssh/sshd_config"
# shellcheck disable=SC2153
sed -i -E "s|^[[:space:]]*ListenAddressIPV4[[:space:]]+.*$|$(printf '%-29s%s' 'ListenAddress' "${VAR_FINAL_IPV4}")|" "${TARGET}/etc/ssh/sshd_config"
if [[ -n "${VAR_FINAL_IPV6}" ]]; then
sed -i -E "s|^[[:space:]]*ListenAddressIPV6[[:space:]]+.*$|$(printf '%-29s%s' 'ListenAddress' "${VAR_FINAL_IPV6}")|" "${TARGET}/etc/ssh/sshd_config"
else
sed -i "/^[[:space:]]*ListenAddressIPV6[[:space:]]*/d" "${TARGET}/etc/ssh/sshd_config"
fi
sed -i -E "s|^[[:space:]]*Port[[:space:]]+.*$|$(printf '%-29s%s' 'Port' "${ssh_port}")|" "${TARGET}/etc/ssh/sshd_config"
if (( ${#ary_user[@]} > 0 )); then
sed -i -E "s|^\s*AllowUsers\s+.*$|$(printf '%-29s%s' 'AllowUsers' "root ${ary_user[*]}")|" "${TARGET}/etc/ssh/sshd_config"
fi
if [[ -n "${ssh_root_ca}" ]]; then
var_ca="${ssh_root_ca##*/}"
install -D -m 0644 -o root -g root "${VAR_SETUP_PATH}${ssh_root_ca}" "${TARGET}/etc/ssh/"
sed -i -E "s|^\s*TrustedUserCAKeys\s+.*$|$(printf '%-29s%s' 'TrustedUserCAKeys' "/etc/ssh/${var_ca}")|" "${TARGET}/etc/ssh/sshd_config"
fi
### Preparing the test environment in chroot.
chroot_exec "${TARGET}" install -d -o root -g root -m 0755 /run/sshd
### Syntax test (hard).
if ! chroot_script "${TARGET}" "sshd -t -f /etc/ssh/sshd_config"; then
do_log "emergency" "file_only" "4420() [sshd -t -f /etc/ssh/sshd_config] failed."
return "${ERR_CONF_VALIDATION}"
fi
### Effective configuration (soft, purely informative).
if ! chroot_script "${TARGET}" "sshd -T -f /etc/ssh/sshd_config >| /root/.ciss/cdi/log/sshd_config.log"; then
do_log "warn" "file_only" "4420() [sshd -T -f /etc/ssh/sshd_config] failed. Likely env. Continuing."
fi
chroot_script "${TARGET}" "ssh-keygen -r ${VAR_FINAL_FQDN}. >| /root/.ciss/cdi/log/SSHFP.log"
###########################################################################################
# The file /etc/profile.d/idle-users.sh is created to set the read-only #
# environment variables: TMOUT #
# TMOUT=14400 ensures that users are automatically logged out after 4 hours of inactivity.#
###########################################################################################
cat << EOF >| "${TARGET}/etc/profile.d/idle-users.sh"
# SPDX-Version: 3.0
# SPDX-CreationInfo: ${VAR_DATE}; WEIDNER, Marc S.; <msw@coresecret.dev>
# SPDX-ExternalRef: GIT https://git.coresecret.dev/msw/CISS.debian.installer.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.installer
# SPDX-Security-Contact: security@coresecret.eu
# Static file system information: /etc/profile.d/idle-users.sh
# Generated by CISS.debian.installer ${VAR_VERSION}
# Architecture: ${VAR_ARCHITECTURE}
# Distribution: ${VAR_CODENAME}
EOF
cat << 'EOF' >> "${TARGET}/etc/profile.d/idle-users.sh"
case $- in
*i*)
TMOUT=14400
export TMOUT
readonly TMOUT
;;
esac
# vim: number et ts=2 sw=2 sts=2 ai tw=128 ft=sh
EOF
chmod 0644 "${TARGET}/etc/profile.d/idle-users.sh"
insert_comments "${TARGET}/etc/profile.d/idle-users.sh"
guard_dir && return 0
}
# vim: number et ts=2 sw=2 sts=2 ai tw=128 ft=sh