diff --git a/README-zh.md b/README-zh.md
index 4f41c65..d34636d 100644
--- a/README-zh.md
+++ b/README-zh.md
@@ -37,8 +37,8 @@ IPsec VPN 可以加密你的网络流量，以防止在通过因特网传送时
- 封装所有的 VPN 流量在 UDP 协议，不需要 ESP 协议支持
- 可直接作为 Amazon EC2 实例创建时的用户数据使用
- 自动确定服务器的公网 IP 以及私有 IP 地址
-- 包括基本的 IPTables 防火墙规则和 `sysctl.conf` 优化设置
-- 测试通过： Ubuntu 16.04/14.04/12.04， Debian 8 和 CentOS 6/7
+- 包含 `sysctl.conf` 优化设置，以达到更佳的传输性能
+- 测试通过： Ubuntu 16.04/14.04/12.04， Debian 8 和 CentOS 7/6
## 系统要求
@@ -133,7 +133,7 @@ DigitalOcean 用户可以参考这个EC2/GCE），请打开 UDP 端口 500 和 4500，以及 TCP 端口 22 （用于 SSH）。
-如果需要打开服务器上的其它端口，请编辑 `/etc/iptables.rules` 和/或 `/etc/iptables/rules.v4` (Ubuntu/Debian)，或者 `/etc/sysconfig/iptables` (CentOS)。然后重启服务器。
+如需更改 IPTables 规则，请编辑 `/etc/iptables.rules` 和/或 `/etc/iptables/rules.v4` (Ubuntu/Debian)，或者 `/etc/sysconfig/iptables` (CentOS)。然后重启服务器。
在使用 `IPsec/L2TP` 连接时，VPN 服务器在虚拟网络 `192.168.42.0/24` 内具有 IP `192.168.42.1`。
diff --git a/README.md b/README.md
index 2dbe8d3..788655b 100644
--- a/README.md
+++ b/README.md
@@ -37,8 +37,8 @@ We will use Libreswan as th
- Encapsulates all VPN traffic in UDP - does not need ESP protocol
- Can be directly used as "user-data" for a new Amazon EC2 instance
- Automatically determines public IP and private IP of server
-- Includes basic IPTables rules and `sysctl.conf` settings
-- Tested with Ubuntu 16.04/14.04/12.04, Debian 8 and CentOS 6 & 7
+- Includes `sysctl.conf` optimizations for improved performance
+- Tested with Ubuntu 16.04/14.04/12.04, Debian 8 and CentOS 7/6
## Requirements
@@ -133,7 +133,7 @@ Clients are set to use EC2/GCE), open UDP ports 500 & 4500, and TCP port 22 (for SSH).
-To open additional ports on the server, edit `/etc/iptables.rules` and/or `/etc/iptables/rules.v4` (Ubuntu/Debian), or `/etc/sysconfig/iptables` (CentOS). Then reboot your server.
+To change the IPTables rules, edit `/etc/iptables.rules` and/or `/etc/iptables/rules.v4` (Ubuntu/Debian), or `/etc/sysconfig/iptables` (CentOS). Then reboot your server.
When connecting via `IPsec/L2TP`, the VPN server has IP `192.168.42.1` within the VPN subnet `192.168.42.0/24`.
diff --git a/docs/clients-zh.md b/docs/clients-zh.md
index 0d8eb23..48a7669 100644
--- a/docs/clients-zh.md
+++ b/docs/clients-zh.md
@@ -315,7 +315,7 @@ route add default dev ppp0
至此 VPN 连接已成功完成。检查 VPN 是否正常工作：
```
-wget -qO- http://whatismyip.akamai.com; echo
+wget -qO- http://ipv4.icanhazip.com; echo
```
以上命令应该返回 `你的 VPN 服务器 IP`。
diff --git a/docs/clients.md b/docs/clients.md
index cdbb2c3..9726e12 100644
--- a/docs/clients.md
+++ b/docs/clients.md
@@ -315,7 +315,7 @@ route add default dev ppp0
The VPN connection is now complete. Verify that your traffic is being routed properly:
```
-wget -qO- http://whatismyip.akamai.com; echo
+wget -qO- http://ipv4.icanhazip.com; echo
```
The above command should return `Your VPN Server IP`.
diff --git a/docs/ikev2-howto-zh.md b/docs/ikev2-howto-zh.md
index ec0f572..2449bdc 100644
--- a/docs/ikev2-howto-zh.md
+++ b/docs/ikev2-howto-zh.md
@@ -24,7 +24,7 @@ Libreswan 支持通过使用 RSA 签名算法的 X.509 Machine Certificates 来
1. 获取服务器的公共和私有 IP 地址，并确保它们的值非空。注意，这两个 IP 地址可以相同。
```bash
- $ PUBLIC_IP=$(wget -t 3 -T 15 -qO- http://whatismyip.akamai.com)
+ $ PUBLIC_IP=$(dig @resolver1.opendns.com -t A -4 myip.opendns.com +short)
$ PRIVATE_IP=$(ip -4 route get 1 | awk '{print $NF;exit}')
$ echo "$PUBLIC_IP"
(Your public IP is displayed)
diff --git a/docs/ikev2-howto.md b/docs/ikev2-howto.md
index 498e0f9..3aa9a79 100644
--- a/docs/ikev2-howto.md
+++ b/docs/ikev2-howto.md
@@ -24,7 +24,7 @@ First, make sure you have successfully