317 lines
10 KiB
Bash
Executable File
317 lines
10 KiB
Bash
Executable File
#!/bin/bash
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# 验证已有公钥后关闭 SSH 密码和 root 登录，并改用 55522 端口
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SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
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# shellcheck disable=SC1091
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source "$SCRIPT_DIR/common/help.sh"
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# shellcheck disable=SC1091
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source "$SCRIPT_DIR/common/os-arch.sh"
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set -euo pipefail
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usage() {
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cat <<'EOF'
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用法: sudo ssh-harden [--user <用户名>] [--skip-key-check] [--yes]
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默认在确认目标用户已有 SSH 公钥后，写入 /etc/ssh/sshd_config.d/99-dotfile-key-only.conf：
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PubkeyAuthentication yes
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PasswordAuthentication no
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KbdInteractiveAuthentication no
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ChallengeResponseAuthentication no
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PermitRootLogin no
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Port 55522
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选项:
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-u, --user <用户名> 要确认公钥的用户；默认使用调用 sudo 前的用户
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-k, --skip-key-check 跳过本地 authorized_keys 与权限检查
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-y, --yes 跳过交互确认
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-h, --help 显示此帮助
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示例:
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sudo ssh-harden
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sudo ssh-harden --user deploy
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sudo ssh-harden -k
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重要说明:
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- 仅支持使用 systemd 管理 SSH 服务的 Linux 服务器。
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- 脚本不会创建 SSH 密钥；目标用户的 ~/.ssh/authorized_keys 中必须已有有效公钥。
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- 使用 -k/--skip-key-check 时，必须已有其他已验证的登录方式（例如 Tailscale SSH
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或云控制台）；该选项仅跳过本地 authorized_keys 检查。
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- 写入前会校验 sshd 配置，且重载后会再次核对生效设置；失败会恢复原文件。
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- 若 UFW 已启用，脚本会自动放行 TCP 55522；云安全组和其他防火墙仍需自行放行。
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- 请保持当前 SSH 会话不要退出，另开一个终端验证密钥登录成功后再关闭。
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EOF
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}
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TARGET_USER="${SUDO_USER:-}"
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ASSUME_YES=0
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SSH_PORT=55522
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UFW_RULE_ADDED=0
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SKIP_KEY_CHECK=0
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while [[ $# -gt 0 ]]; do
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case "$1" in
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-h|--help)
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dotfile_show_help
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;;
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-u|--user)
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[[ $# -ge 2 ]] || { echo "错误: $1 需要用户名" >&2; exit 1; }
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TARGET_USER="$2"
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shift 2
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;;
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-y|--yes)
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ASSUME_YES=1
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shift
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;;
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-k|--skip-key-check)
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SKIP_KEY_CHECK=1
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shift
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;;
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*)
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echo "错误: 不支持参数: $1" >&2
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usage >&2
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exit 1
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;;
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esac
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done
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die() {
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echo "错误: $*" >&2
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exit 1
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}
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find_sshd() {
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local candidate
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if command -v sshd >/dev/null 2>&1; then
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command -v sshd
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return
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fi
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for candidate in /usr/sbin/sshd /usr/local/sbin/sshd; do
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[[ -x "$candidate" ]] && { printf '%s\n' "$candidate"; return; }
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done
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}
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user_home() {
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local user="$1" home
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if command -v getent >/dev/null 2>&1; then
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home=$(getent passwd "$user" | awk -F: 'NR == 1 {print $6}')
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fi
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printf '%s' "${home:-}"
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}
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setting_value() {
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local setting="$1"
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printf '%s\n' "$EFFECTIVE_CONFIG" | awk -v key="$setting" '$1 == key {print $2; exit}'
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}
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check_ssh_path_permissions() {
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local path="$1" owner mode
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owner=$(stat -c '%U' "$path")
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mode=$(stat -c '%a' "$path")
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[[ "$owner" == "$TARGET_USER" || "$owner" == "root" ]] || die "$path 的属主为 $owner，应为 $TARGET_USER 或 root"
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(( (8#$mode & 022) == 0 )) || die "$path 对组或其他用户可写（权限: $mode），sshd 可能会忽略其中的公钥"
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}
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config_is_hardened() {
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local ports
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EFFECTIVE_CONFIG=$("$SSHD_BIN" -T -f "$SSHD_CONFIG" 2>/dev/null || true)
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[[ "$(setting_value pubkeyauthentication)" == "yes" ]] || return 1
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[[ "$(setting_value passwordauthentication)" == "no" ]] || return 1
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[[ "$(setting_value kbdinteractiveauthentication)" == "no" ]] || return 1
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[[ "$(setting_value permitrootlogin)" == "no" ]] || return 1
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ports=$(printf '%s\n' "$EFFECTIVE_CONFIG" | awk '$1 == "port" {print $2}')
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[[ "$ports" == "$SSH_PORT" ]] || return 1
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}
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port_is_in_use() {
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if command -v ss >/dev/null 2>&1; then
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ss -H -ltn "sport = :$SSH_PORT" 2>/dev/null | grep -q .
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return
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fi
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if command -v netstat >/dev/null 2>&1; then
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netstat -ltn 2>/dev/null | grep -Eq "[.:]${SSH_PORT}[[:space:]]"
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return
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fi
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return 1
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}
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sshd_already_uses_port() {
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local current_config
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current_config=$("$SSHD_BIN" -T -f "$SSHD_CONFIG" 2>/dev/null || true)
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printf '%s\n' "$current_config" | awk -v port="$SSH_PORT" '$1 == "port" && $2 == port {found = 1} END {exit !found}'
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}
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ensure_ufw_port() {
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local status
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if ! command -v ufw >/dev/null 2>&1; then
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echo "未安装 UFW，跳过防火墙规则修改。"
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return 0
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fi
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status=$(ufw status 2>&1)
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if ! printf '%s\n' "$status" | grep -qi '^Status: active'; then
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echo "UFW 未启用，跳过防火墙规则修改。"
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return 0
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fi
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if printf '%s\n' "$status" | grep -Eq "^[[:space:]]*${SSH_PORT}(/tcp)?[[:space:]]"; then
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echo "UFW 已有 TCP $SSH_PORT 规则，跳过。"
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return 0
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fi
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if ! ufw allow "$SSH_PORT/tcp"; then
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echo "无法通过 UFW 放行 TCP $SSH_PORT。" >&2
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return 1
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fi
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UFW_RULE_ADDED=1
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echo "已通过 UFW 放行 TCP $SSH_PORT。"
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return 0
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}
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rollback_ufw_port() {
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if [[ $UFW_RULE_ADDED -eq 1 ]]; then
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if ufw --force delete allow "$SSH_PORT/tcp" >/dev/null 2>&1; then
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echo "已删除本次新增的 UFW TCP $SSH_PORT 规则。" >&2
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else
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echo "警告: 未能自动删除本次新增的 UFW TCP $SSH_PORT 规则，请手动检查。" >&2
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fi
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fi
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}
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reload_sshd() {
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local unit
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for unit in ssh sshd; do
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if systemctl reload "$unit" >/dev/null 2>&1; then
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return 0
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fi
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done
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return 1
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}
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if [[ $EUID -ne 0 ]]; then
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die "请使用 sudo 运行，例如: sudo $0${TARGET_USER:+ --user "$TARGET_USER"}"
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fi
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[[ "$(get_os)" == "linux" ]] || die "当前仅支持 systemd 管理 SSH 服务的 Linux 服务器"
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command -v systemctl >/dev/null 2>&1 || die "未找到 systemctl，无法安全重载 SSH 服务"
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if [[ $SKIP_KEY_CHECK -eq 0 ]]; then
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[[ -n "$TARGET_USER" ]] || die "无法识别目标用户；请指定 --user <用户名>"
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id "$TARGET_USER" >/dev/null 2>&1 || die "用户不存在: $TARGET_USER"
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TARGET_HOME=$(user_home "$TARGET_USER")
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[[ -n "$TARGET_HOME" && -d "$TARGET_HOME" ]] || die "无法确定用户主目录: $TARGET_USER"
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AUTHORIZED_KEYS="$TARGET_HOME/.ssh/authorized_keys"
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[[ -r "$AUTHORIZED_KEYS" ]] || die "未找到可读取的公钥文件: $AUTHORIZED_KEYS"
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[[ -d "$TARGET_HOME/.ssh" ]] || die "未找到 SSH 配置目录: $TARGET_HOME/.ssh"
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check_ssh_path_permissions "$TARGET_HOME"
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check_ssh_path_permissions "$TARGET_HOME/.ssh"
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check_ssh_path_permissions "$AUTHORIZED_KEYS"
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if ! grep -Eq '^[[:space:]]*(ssh-(rsa|ed25519|dss)|ecdsa-sha2-nistp(256|384|521)|sk-ssh-ed25519@openssh\.com|sk-ecdsa-sha2-nistp256@openssh\.com|[[:alnum:]_-]+-cert-v01@openssh\.com)[[:space:]]+' "$AUTHORIZED_KEYS"; then
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die "$AUTHORIZED_KEYS 中未发现有效的 SSH 公钥，已取消以避免锁定访问"
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fi
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fi
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SSHD_BIN=$(find_sshd)
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[[ -n "$SSHD_BIN" ]] || die "未找到 sshd"
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SSHD_CONFIG=/etc/ssh/sshd_config
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[[ -r "$SSHD_CONFIG" ]] || die "无法读取 $SSHD_CONFIG"
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if ! grep -Eq '^[[:space:]]*Include[[:space:]].*sshd_config\.d' "$SSHD_CONFIG"; then
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die "$SSHD_CONFIG 未包含 sshd_config.d；为避免覆盖现有规则，未作修改"
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fi
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DROP_IN_DIR=/etc/ssh/sshd_config.d
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DROP_IN="$DROP_IN_DIR/99-dotfile-key-only.conf"
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mkdir -p "$DROP_IN_DIR"
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if ! sshd_already_uses_port && port_is_in_use; then
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die "TCP $SSH_PORT 已被其他服务监听；请选择空闲端口后再修改脚本"
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fi
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echo "将为 SSH 启用公钥认证，关闭密码、交互式认证和 root 登录，并改用端口 $SSH_PORT。"
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if [[ $SKIP_KEY_CHECK -eq 1 ]]; then
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echo "已选择跳过本地 authorized_keys 检查。"
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echo "请确认仍可通过其他已验证方式登录。"
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else
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echo "已确认 $TARGET_USER 的公钥文件: $AUTHORIZED_KEYS"
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fi
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echo "配置文件: $DROP_IN"
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echo "若 UFW 已启用，脚本会自动放行 TCP $SSH_PORT；请确认云安全组已放行。"
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if [[ $ASSUME_YES -ne 1 ]]; then
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if [[ $SKIP_KEY_CHECK -eq 1 ]]; then
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read -r -p "确认仍有其他登录方式且云安全组已放行 TCP $SSH_PORT？[y/N] " answer
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else
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read -r -p "确认云安全组已放行 TCP $SSH_PORT 并继续？[y/N] " answer
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fi
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[[ "$answer" =~ ^[Yy]$ ]] || { echo "已取消，未修改配置。"; exit 0; }
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fi
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STAMP=$(date +%Y%m%d%H%M%S)
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BACKUP=""
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if [[ -f "$DROP_IN" ]]; then
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BACKUP="${DROP_IN}.bak.${STAMP}"
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cp -p "$DROP_IN" "$BACKUP"
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fi
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TMP_FILE=$(mktemp "${DROP_IN}.tmp.XXXXXX")
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VALIDATION_ERROR=$(mktemp)
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trap 'rm -f "$TMP_FILE" "$VALIDATION_ERROR"' EXIT
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cat >"$TMP_FILE" <<'EOF'
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# Managed by ~/.dotfile/script/ssh-harden.sh
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PubkeyAuthentication yes
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PasswordAuthentication no
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KbdInteractiveAuthentication no
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ChallengeResponseAuthentication no
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PermitRootLogin no
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Port 55522
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EOF
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install -m 0600 -o root -g root "$TMP_FILE" "$DROP_IN"
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restore_drop_in() {
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if [[ -n "$BACKUP" ]]; then
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cp -p "$BACKUP" "$DROP_IN"
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else
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rm -f "$DROP_IN"
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fi
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}
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if ! ensure_ufw_port; then
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restore_drop_in
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die "UFW 规则添加失败，已恢复原 SSH 配置"
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fi
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if ! "$SSHD_BIN" -t -f "$SSHD_CONFIG" 2>"$VALIDATION_ERROR"; then
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restore_drop_in
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rollback_ufw_port
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echo "sshd 配置校验输出：" >&2
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cat "$VALIDATION_ERROR" >&2
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die "新配置未通过校验，已恢复原文件"
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fi
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if ! config_is_hardened; then
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restore_drop_in
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rollback_ufw_port
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die "新配置未成为 sshd 的生效设置（可能被更早的配置覆盖），已恢复原文件"
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fi
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if ! reload_sshd; then
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restore_drop_in
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rollback_ufw_port
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die "无法重载 ssh/sshd 服务，已恢复原文件；请检查 systemctl 状态"
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fi
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if ! config_is_hardened; then
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restore_drop_in
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reload_sshd || true
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rollback_ufw_port
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die "重载后设置未生效，已恢复原文件并尝试重载旧配置"
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fi
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echo "已启用仅公钥 SSH 登录，已禁止 root 登录，SSH 端口已改为 $SSH_PORT。"
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[[ -n "$BACKUP" ]] && echo "原配置已备份到: $BACKUP"
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echo "请保持当前会话，另开终端确认可通过密钥连接到端口 $SSH_PORT 后再退出。"
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