更新文档内容

1.Linux基础/1.1常用shell/防火墙相关.md

@@ -44,5 +44,4 @@ iptables -t raw -F
 iptables -t raw -X
 iptables -t raw -P PREROUTING ACCEPT
 iptables -t raw -P OUTPUT ACCEPT
-
 ```

1.Linux基础/1.3系统设置/11文件打开数.md

@@ -0,0 +1,35 @@
+## ulimit
+
+### PAM模块
+
+ssh 开启 pam 模块后应修改以下文件
+
+- /etc/pam.d/su 
+- /etc/pam.d/sshd 
+- /etc/pam.d/login 
+- /etc/pam.d/cron
+
+添加如下内容
+
+```shell
+session required pam_limits.so
+```
+
+重启生效
+
+```shell
+systemctl restart sshd
+```
+
+修改`/etc/security/limits.conf`文件，用户列不能用`*`号，否则`root`登录后执行`ulimit -n` 值不对
+
+```shell
+root	soft	nofile	1048567
+root	hard	nofile	1048567
+root	soft	nproc	65535
+root	hard	nproc	65535
+```
+
+```shell
+NOTE: group and wildcard limits are not applied to the root user. To set a limit for the root user, this field must contain the literal username root.
+```