The database of the server cannot be connected [the service has been started, the firewall has been closed, the port has been opened, and the netlent port is not connected]

The database of the server is disconnected 【 Service started 、 Firewall OFF 、 The port is open 、netlent Port failure 】

First of all ： This article aims at The service is up 、 The firewall is closed 、 The security group port is also open , stay docker Containers can be connected MySQL, however Navicat You can't even , meanwhile netlent IP port Also different ,Navicat An error is as follows ：

If you are such a wonderful problem , You can look at the following solutions .

First, confirm the firewall status

systemctl status firewalld

No problem , It's closed .

Look at the port

netstat -antulp | grep XXXX

No problem ,docker mysql The port is in use ,docker mysql If it's closed , Port is not used

Confirm whether the port corresponding to the security group of your server is open

telnet IP port Test the connection

As a result, the connection failed , Don't worry , Then down

Carry out orders ：cat /proc/sys/net/ipv4/ip_forward

Be careful , Here is 0, It is not right ,0 Express ipv4 Forwarding is off

We need to change it to 1

Carry out orders echo 1 > /proc/sys/net/ipv4/ip_forward

So we'll Open the ipv4 forward

Navicat Reconnection

OK, That's it , I don't know what caused ipv4 forward Shut down the

Probable cause ：

After restarting the server, it was restored

Some processes may have modified the system settings

We put ipv4 Just open forwarding , because To deploy a container in the server, you need to open it ip Forwarding function , Generally, we don't need to deal with it by ourselves , I don't know why I met , We can solve the problem by opening it .

Copyright notice ：
Original Blogger ： Cowherd Conan
Personal blog links ：https://www.keafmd.top/

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