diff --git a/backend/internal/admin/nginx_units_test.go b/backend/internal/admin/nginx_units_test.go
index 20c98e5..7a039b1 100644
--- a/backend/internal/admin/nginx_units_test.go
+++ b/backend/internal/admin/nginx_units_test.go
@@ -19,7 +19,7 @@ func TestNginxActivationDeploymentPolicy(t *testing.T) {
 			"Requires=scert-nginx.socket nginx.service", "PartOf=nginx.service", "User=root", "Group=root",
 			"ExecStart=/usr/local/libexec/scert-nginx --policy /etc/scert-nginx/policy.json",
 			"NoNewPrivileges=yes", "ProtectSystem=strict", "ProtectHome=yes", "PrivateTmp=yes",
-			"CapabilityBoundingSet=CAP_DAC_OVERRIDE CAP_CHOWN", "AmbientCapabilities=",
+			"CapabilityBoundingSet=CAP_DAC_OVERRIDE CAP_CHOWN CAP_NET_BIND_SERVICE", "AmbientCapabilities=",
 			"RestrictAddressFamilies=AF_UNIX AF_INET AF_INET6", "TimeoutStopSec=40",
 		},
 	} {
diff --git a/deploy/nginx/Nginx辅助服务部署说明.md b/deploy/nginx/Nginx辅助服务部署说明.md
index 4223035..681e6d5 100644
--- a/deploy/nginx/Nginx辅助服务部署说明.md
+++ b/deploy/nginx/Nginx辅助服务部署说明.md
@@ -79,3 +79,9 @@ systemctl status scert-nginx.socket --no-pager
 升级前等待应用协调与辅助事务均结束，停止相关变更任务，再停止 socket 和辅助服务。检查它们均已停止后才替换 root 所有的辅助程序，保留旧程序及校验摘要；不重复初始化、不清空版本或请求记录，重新启动 socket 后复验。
 
 辅助程序状态与应用协调记录必须成套备份。现有应用完整备份不包含 `/etc/scert-nginx`、`/var/lib/scert-nginx` 和 Nginx 站点配置，不能声称只恢复应用备份就完成双层灾难恢复。停止变更并核对终态后，另行备份这些 root 文件、服务模板与 include 依赖；恢复时核对 UID、策略、应用证书路径、两层实际证书和事务记录一致。任何未决或损坏记录均保持保护，交由维护人员检查，不通过删除记录解除保护。
+
+## 标准低端口部署的能力要求
+
+当现有 Nginx 监听 80 或 443 等特权端口时，配置检查也可能执行端口绑定检查。独立激活服务的能力白名单因此包含 `CAP_NET_BIND_SERVICE`，同时保留 `CAP_DAC_OVERRIDE` 与 `CAP_CHOWN`。不要把该能力添加到 Scert 主服务，也不要取消 `NoNewPrivileges`、只读文件系统或本机 Unix socket 身份校验。
+
+更新已部署的辅助服务模板后，先执行 `systemd-analyze verify`，再执行 `systemctl daemon-reload` 和 `systemctl restart scert-nginx.service`。须通过页面触发实际续期并核对结果，不能把 root 终端中单独执行 `nginx -t` 的成功当作受限服务运行成功。
diff --git a/deploy/systemd/scert-nginx.service b/deploy/systemd/scert-nginx.service
index fcc0111..93f3f2a 100644
--- a/deploy/systemd/scert-nginx.service
+++ b/deploy/systemd/scert-nginx.service
@@ -15,7 +15,7 @@ TimeoutStopSec=40
 Restart=on-failure
 RestartSec=5
 NoNewPrivileges=yes
-CapabilityBoundingSet=CAP_DAC_OVERRIDE CAP_CHOWN
+CapabilityBoundingSet=CAP_DAC_OVERRIDE CAP_CHOWN CAP_NET_BIND_SERVICE
 AmbientCapabilities=
 PrivateTmp=yes
 PrivateDevices=yes