连接 VPN 之后，经常打不开国内的某些网站。经高人指点，这是 DNS 的问题，推荐使用DNSMasq，在本机架设简易的 DNS 服务器，让 VPN 使用本地服务器解析域名。以下对安装的过程做一记录，以备不时之需。
我使用的系统是 Mac OS X，因此使用 homebrew 安装。安装方式如下：
$ brew up & brew install dnsmasq
DNSMasq 比较小，下载过程很快。
然后，根据 homebrew 的提示，执行几个命令：
cp /usr/local/opt/dnsmasq/dnsmasq.conf.example /usr/local/etc/dnsmasq.conf
sudo cp -fv /usr/local/opt/dnsmasq/*.plist /Library/LaunchDaemons
sudo launchctl load /Library/LaunchDaemons/homebrew.mxcl.dnsmasq.plist
这三个命令的作用分别是：
为了操作方便，我还定义了两个命令别名，用于手动启动和停止 DNSMasq：
alias start-dnsmasq="sudo launchctl start homebrew.mxcl.dnsmasq"
alias stop-dnsmasq="sudo launchctl stop homebrew.mxcl.dnsmasq"
DNSMasq 的配置文件是 /usr/local/etc/dnsmasq.conf。在文本编辑器中打开，在文件末尾写入如下设置（via）：
server=8.8.8.8
server=8.8.4.4
#Bilibili
server=/bilibili.com/114.114.114.114
#fm
server=/jing.fm/114.114.114.114
server=/xiami.com/114.114.114.114
#Baidu
server=/baidu.com/114.114.114.114
server=/bdstatic.com/114.114.114.114
#QQ
server=/qq.com/114.114.114.114
server=/qcloud.com/114.114.114.114
#Taobao
server=/taobao.com/114.114.114.114
server=/tmall.com/114.114.114.114
server=/alipay.com/114.114.114.114
server=/alibaba.com/114.114.114.114
server=/taobaocdn.com/114.114.114.114
#Sina
server=/sina.com.cn/114.114.114.114
server=/weibo.com/114.114.114.114
#163
server=/163.com/114.114.114.114
server=/youdao.com/114.114.114.114
server=/netease.com/114.114.114.114
#Zhihu
server=/zhihu.com/114.114.114.114
server=/zhimg.com/114.114.114.114
#Apple
server=/apple.com/114.114.114.114
server=/autonavi.com/114.114.114.114
#Sohu
server=/sohu.com/114.114.114.114
server=/sogou.com/114.114.114.114
#Ifeng
server=/ifeng.com/114.114.114.114
server=/360.cn/114.114.114.114
#Youku
server=/youku.com/114.114.114.114
server=/ykimg.com/114.114.114.114
server=/tudou.com/114.114.114.114
server=/soku.com/114.114.114.114
#douban
server=/douban.com/114.114.114.114
#TV
server=/pptv.com/114.114.114.114
server=/ppstream.com/114.114.114.114
server=/pps.tv/114.114.114.114
server=/letv.com/114.114.114.114
server=/56.com/114.114.114.114
server=/58.com/114.114.114.114
server=/iqiyi.com/114.114.114.114
server=/cntv.cn/114.114.114.114
#ShopMall
server=/51buy.com/114.114.114.114
server=/yixun.com/114.114.114.114
server=/yihaodian.com/114.114.114.114
server=/dangdang.com/114.114.114.114
server=/qunar.com/114.114.114.114
server=/meituan.com/114.114.114.114
server=/jd.com/114.114.114.114
server=/360buyimg.com/114.114.114.114
#Xunlei
server=/xunlei.com/114.114.114.114
server=/kankan.com/114.114.114.114
#Ruby China
server=/ruby-china.org/114.114.114.114
#CDN
server=/tanx.com/114.114.114.114
server=/aliyun.com/114.114.114.114
server=/upaiyun.com/114.114.114.114
#Map
server=/amap.com/114.114.114.114
server=/hvvc.us/114.114.114.114
#cn
server=/cn/114.114.114.114
#guokr
server=/guokr.com/114.114.114.114
如果之前已经启动 DNSMasq，现在重启。
打开 VPN 的高级设置，在 DNS 选项卡中填入 127.0.0.1，让 VPN 使用本地 DNS 服务器解析域名。