mobaXterm connects to Linux (Ubuntu or centos7) virtual machine, Network error: Connection refused

centos7:

问题：连接本地虚拟机时，连接不上，报错--Network error: Connection refused
原因：
1.刚开始直接ping主机，是可以ping通的，说明网络是正常的
[root@szb ~]# ping 192.168.8.132
PING 192.168.8.132 (192.168.8.132) 56(84) bytes of data.
64 bytes from 192.168.8.132: icmp_seq=1 ttl=64 time=0.969 ms
64 bytes from 192.168.8.132: icmp_seq=2 ttl=64 time=4.00 ms

2.查询sshd安装了没,说明是存在的
[ly@192 ~]$ ps -e |grep ssh
  8245 ?        00:00:00 ssh-agent
  
3.ss -ntl 查询22端口是否开启，此处没有22端口
[ly@192 ~]$ ss -ntl
State      Recv-Q Send-Q Local Address:Port               Peer Address:Port         
LISTEN     0      5      192.168.122.1:53                       *:*                  
LISTEN     0      128    127.0.0.1:631                      *:*                  
LISTEN     0      128      [::1]:631                   [::]:*                  
解决办法：确认一下是否还是默认的端口，vim /etc/ssh/sshd_config,显示没有被修改

4.重启sshd服务,在查看端口，已经存在22端口了，MobaXterm软件重连接，可以了
systemctl restart sshd

Ubuntu 18.04:

sudo apt-get update 

sudo apt-get install -y openssh-server

systemctl start sshd

 Find your Ubuntu IP address

ifconfig

 Finally open mobaXterm

 Seeing that the connection is successful