# 自建DDNS說明-ChangeIP

## 由於網路安全原因，我們停止了免費域名（DDNS）的解析，但用戶仍然可以通過自建DDNS獲取伺服器的外網IP。

## 下面我們將使用changeip.com的免費DDNS服務，建立您的DDNS。

#### ​1. 打開下方鏈接登記你的DDNS

<https://www.changeip.com/accounts/cart.php?a=confproduct&i=1>

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{% hint style="info" %}
到此，您已經獲得一個免費域名`ip.yourname.ddns.info`
{% endhint %}

#### 2. 使用腳本讓VPS自動更新DDNS

登入您的vps終端新建一個名為`ddns.sh`的腳本

```
nano /root/ddns.sh

或者

vi /root/ddns.sh
```

黏貼下面的腳本，注意修改11、12、13行為您自己的信息，並保存。

```
#!/bin/bash
# Changeip.com Script for Linux base systems using bash
# Created to suite local need in specific case. Well tested with CENTOS 6.x n UBUNTU 12.x
# Syed . Jahanzaib . aacable at hotmail dot com
# October , 2015
# Uncomment below to view debug log
# set -x
 
# Various variables, make sure to change the changeip.com credentials and hostname as required.

CIPUSER=您在ChangeIP登記的郵箱
CIPPASS=您在ChangeIP設定的密碼
CIPHOST=您在ChangeIP設定的域名

URL="http://nic.changeip.com/nic/update?ip"
# Temp files and log file to record updates if required
EXTIP="/tmp/externalip.txt"
NEWIP="/tmp/newip.txt"
LOG="/var/log/changeip.log"
DATE=`date`
 
# If external ip text file not found, then create one
if [ ! -e "$EXTIP" ] ; then
touch "$EXTIP"
fi
 
# Download current LIVE ip from intenret to match with old ip
wget -q -O /tmp/newip.txt http://ip.changeip.com:8245
a=`cat $EXTIP`
b=`cat $NEWIP  | cut -f 2 -d "=" | cut -f 1 -d "-" -s | grep -m 1 ^`
if [[ $a != "$b" ]]
then
 
# changeip update now
curl -4 "$URL=$b&u=$CIPUSER&p=$CIPPASS&hostname=$CIPHOST"
 
# Update New WAN IP in OLD File
echo $b > $EXTIP
echo
 
# Print OLD vs New Comparision for REVIEW
echo Old IP = $a
echo New IP = $b
echo Update Time = $DATE
echo Update Done.
 
# Print OLD vs New Comparision for REVIEW in LOG FILE for later review
echo "*********************************************"  >> $LOG
echo New IP FOUND > $LOG
echo Old IP = $a >> $LOG
echo New IP found at $DATE and IP is = $b >> $LOG
 
# IF OLD and NEW ip are same, then no need to update, just EXIT
else
echo $DATE / No need to change IP. DDNS BASH Script / Powered by Syed Jahanzaib
fi
 
# END
```

修改腳本權限，並測試腳本是否有效

```
chmod +x /root/ddns.sh
bash /root/ddns.sh


###返回下面資訊即代表腳本正常###

200 Successful Update
Old IP = 219.76.163.216
New IP = 220.246.88.57
Update Time = Sat Feb 8 22:11:04 CST 2020
Update Done.
```

設定定時更新

```
crontab -e
```

貼上下方命令並保存

```
*/1 * * * * /root/ddns.sh >/dev/null 2>&1 &
```

{% hint style="success" %}
至此所有步驟完成，當IP變更時腳本會自動更新A紀錄指向您的域名

您可以登入changeip.com後台查看域名IP

並可以使用您的DDNS連接您的VPS
{% endhint %}

{% hint style="info" %}
需要注意的是DDNS生效時間存在地區差異，請耐心等待DNS更新。
{% endhint %}