中文版：一次Tailscale网络问题的调试过程 – Frank’s Weblog

As mentioned in an earlier post, I used Tailscale to create a mesh network that connects all of my devices, and I used a cloud server located in AliCloud Beijing as an exit node, in order to access geographically restricted internet services.

However, I noticed that I could not access the Internet at all when using that exit node. I thought it was a network connectivity issue with the relays, so I didn’t worry too much about it. But afterward, I noticed some other services on that server stopped functioning, so I looked into it and found out that the problem was not that simple.

First I noticed that I couldn’t access the internet at all from the server, but curl the IP address was working, which indicated the problem with DNS resolution. resolvectl status showed that there were two DNS servers. I assumed this was the DNS server for the Tailscale internal network (actually not, will elaborate later) since the IPs started with 100.100^[1],

Link 2 (eth0)
......
  Current DNS Server: 100.100.2.136
         DNS Servers: 100.100.2.136
                      100.100.2.138

I tried dig @100.100.2.136 baidu.com to check the response from the DNS server and got connection timed out: no servers could be reached. The response from the command became normal after shutting down Tailscale. So probably Tailscale somehow affected the DNS resolution on the system.

English version: Troubleshooting Tailscale Network – Frank’s Weblog

前文提到，我使用Tailscale将我的所有设备组成了一个Mesh网络，并且将位于阿里云北京的轻量应用服务器作为出口节点用于访问一些限制地理位置的网络服务。

然而我却发现在使用该出口节点时完全无法访问互联网。我本以为是Relay的网络质量问题就没有在意。但是后来陆续发现该服务器上的其他一些服务都出现了问题，于是进行了一番检查，结果发现问题并没有这么简单。

首先我发现从服务器上完全无法访问互联网，但是直接curl IP地址是可以的，这样就基本上将问题定位到了DNS上。resolvectl status显示有两个DNS服务器，因为IP以100.100打头^[1]，我以为这是Tailscale内网的DNS服务器（实际上不是，请看后文）。

Link 2 (eth0)
......
  Current DNS Server: 100.100.2.136
         DNS Servers: 100.100.2.136
                      100.100.2.138

我试图dig @100.100.2.136 baidu.com来检查DNS服务器的回应，得到connection timed out: no servers could be reached.。关掉Tailscale之后，上述命令的回应则正常。因此我认为问题在于Tailscale从某种形式上影响了系统的DNS解析。