Marc S. Weidner
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Signed-off-by: Marc S. Weidner <msw@coresecret.dev>
111 lines
5.1 KiB
Bash
111 lines
5.1 KiB
Bash
#!/bin/bash
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# SPDX-Version: 3.0
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# SPDX-CreationInfo: 2025-06-17; WEIDNER, Marc S.; <msw@coresecret.dev>
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# SPDX-ExternalRef: GIT https://git.coresecret.dev/msw/CISS.debian.installer.git
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# SPDX-FileContributor: WEIDNER, Marc S.; Centurion Intelligence Consulting Agency
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# SPDX-FileCopyrightText: 2024-2025; WEIDNER, Marc S.; <msw@coresecret.dev>
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# SPDX-FileType: SOURCE
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# SPDX-License-Identifier: EUPL-1.2 OR LicenseRef-CCLA-1.0
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# SPDX-LicenseComment: This file is part of the CISS.debian.installer.secure framework.
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# SPDX-PackageName: CISS.debian.installer
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# SPDX-Security-Contact: security@coresecret.eu
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guard_sourcing
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#######################################
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# Hardening 'ufw'.
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# Globals:
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# RECOVERY
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# TARGET
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# VAR_FINAL_NIC
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# VAR_RUN_RECOVERY
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# VAR_SSH_PORT
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# VAR_UFW_OUT
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# Arguments:
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# None
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# Returns:
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# 0: on success
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#######################################
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hardening_ufw() {
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### Declare Arrays, HashMaps, and Variables.
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declare -r var_logfile="/root/.ciss/cdi/log/4470_hardening_ufw.log"
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declare var_target="${TARGET}"
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### Check for TARGET / RECOVERY.
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[[ "${VAR_RUN_RECOVERY}" == "true" ]] && var_target="${RECOVERY}"
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declare -r var_rules="${var_target}/etc/ufw/before6.rules"
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chroot_logger "${var_target}${var_logfile}"
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if [[ ! -f "${var_target}/var/log/ufw.log" ]]; then
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touch "${var_target}/var/log/ufw.log"
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chmod 0640 "${var_target}/var/log/ufw.log"
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fi
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chroot_script "${var_target}" "
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ufw --force reset
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ufw logging medium
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ufw default deny incoming
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ufw default ${VAR_UFW_OUT} outgoing
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ufw default deny forward
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ufw allow in ${VAR_SSH_PORT}/tcp comment 'Incoming SSH'
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ufw limit ${VAR_SSH_PORT}/tcp comment 'Incoming SSH'
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"
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### Ensure that a standard set of the most commonly used ports are open if a default-'deny'-outbound policy is selected.
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if [[ "${VAR_UFW_OUT}" = "deny" ]]; then
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chroot_script "${var_target}" "
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ufw allow out 21/tcp comment 'Outgoing FTP'
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ufw allow out 22/tcp comment 'Outgoing SSH'
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ufw allow out 25/tcp comment 'Outgoing SMTP'
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ufw allow out 53/tcp comment 'Outgoing DNS'
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ufw allow out 80/tcp comment 'Outgoing HTTP'
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ufw allow out 123/tcp comment 'Outgoing NTP'
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ufw allow out 143/tcp comment 'Outgoing IMAP'
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ufw allow out 443/tcp comment 'Outgoing HTTPS'
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ufw allow out 465/tcp comment 'Outgoing SMTPS'
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ufw allow out 587/tcp comment 'Outgoing SMTPS'
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ufw allow out 993/tcp comment 'Outgoing IMAPS'
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ufw allow out 4460/tcp comment 'Outgoing NTS'
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ufw allow out ${VAR_SSH_PORT}/tcp comment 'Outgoing SSH'
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ufw allow out 53/udp comment 'Outgoing DNS'
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ufw allow out 123/udp comment 'Outgoing NTP'
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ufw allow out 443/udp comment 'Outgoing QUIC'
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ufw allow out 853/udp comment 'Outgoing DoQ'
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"
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fi
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### Allowing ICMP IPv4 outgoing per default.
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sed -i "/# ok icmp code for FORWARD/i \# ok icmp codes for OUTPUT" "${var_target}/etc/ufw/before.rules"
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sed -i "/# ok icmp code for FORWARD/i \-A ufw-before-output -p icmp --icmp-type destination-unreachable -j ACCEPT" "${var_target}/etc/ufw/before.rules"
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sed -i "/# ok icmp code for FORWARD/i \-A ufw-before-output -p icmp --icmp-type time-exceeded -j ACCEPT" "${var_target}/etc/ufw/before.rules"
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sed -i "/# ok icmp code for FORWARD/i \-A ufw-before-output -p icmp --icmp-type parameter-problem -j ACCEPT" "${var_target}/etc/ufw/before.rules"
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sed -i "/# ok icmp code for FORWARD/i \-A ufw-before-output -p icmp --icmp-type echo-request -j ACCEPT" "${var_target}/etc/ufw/before.rules"
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### Remove previous custom blocks (idempotent).
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sed -i "/^# BEGIN custom MLD rules/,/^# END custom MLD rules/d" "${var_rules}"
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sed -i "/^# BEGIN custom MLD OUTPUT rules/,/^# END custom MLD OUTPUT rules/d" "${var_rules}"
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### Inbound MLD (INPUT chain), insert before the existing echo-request rule.
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### Allows MLDv1 (130/131/132) and MLDv2 (143) to link-local multicast (ff02::/16)
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sed -i "/-A ufw6-before-input .*--icmpv6-type echo-request -j ACCEPT/i # BEGIN custom MLD rules\n-A ufw6-before-input -i ${VAR_FINAL_NIC} -p icmpv6 --icmpv6-type 130 -d ff02::/16 -j ACCEPT\n-A ufw6-before-input -i ${VAR_FINAL_NIC} -p icmpv6 --icmpv6-type 131 -d ff02::/16 -j ACCEPT\n-A ufw6-before-input -i ${VAR_FINAL_NIC} -p icmpv6 --icmpv6-type 132 -d ff02::/16 -j ACCEPT\n-A ufw6-before-input -i ${VAR_FINAL_NIC} -p icmpv6 --icmpv6-type 143 -d ff02::/16 -j ACCEPT\n# END custom MLD rules" "${var_rules}"
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### Outbound MLD (OUTPUT chain), insert before echo-request.
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### Useful if local daemons join multicast groups, and you want clean logs.
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sed -i "/-A ufw6-before-output .*--icmpv6-type echo-request -j ACCEPT/i # BEGIN custom MLD OUTPUT rules\n-A ufw6-before-output -o ${VAR_FINAL_NIC} -p icmpv6 --icmpv6-type 131 -d ff02::/16 -j ACCEPT\n-A ufw6-before-output -o ${VAR_FINAL_NIC} -p icmpv6 --icmpv6-type 143 -d ff02::/16 -j ACCEPT\n# END custom MLD OUTPUT rules" "${var_rules}"
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chroot_script "${var_target}" "echo 'y' | ufw enable 2>&1"
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chroot_script "${var_target}" "ufw status verbose >> ${var_logfile}"
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guard_dir && return 0
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}
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### Prevents accidental 'unset -f'.
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# shellcheck disable=SC2034
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readonly -f hardening_ufw
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# vim: number et ts=2 sw=2 sts=2 ai tw=128 ft=sh
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