First step ： If the machine is blocked, see if it is pulled or pulled by the intranet , open kvm Check to see if the system is working properly .1. Remote port access , Try remote , It depends on the error reported ; Entry system , See if it's a rule （ example ：/etc/ssh/sshd_config、/etc/hosts.allow 、/etc/hosts.deny、 Firewall, etc ） Or security software （ Cloud lock, etc ） Restrict login
The second step ： Remote port access , Try remote , Let's see if the white list of safety dogs is opened ;kvm Can't log in , You can first ask the customer if they can restart 2. The remote port is blocked ,“80” Port on ; open kvm Enter the customer system , Use command ”netstat -lntup” You can see that ssh Service port ,ssh Whether it runs or is consistent with the customer submission , Such as ssh The normal operation , The port is consistent with the customer submission ：1、 See if the firewall adds an exception 2、 Check the log , Try changing the port first , See if you can remote （ Consider that the port may be blocked by domestic ）
The third step ： The remote port is blocked. Enter the system to see if the firewall has been released , Check the log
Step four ： The remote port is seriously swapped ,“80” Port or IP Long ping normal , Consider brute force , Entry system ,cmd Windows use commands “netstat -an” , Check the details .
Step five ： Other reasons , Solve according to the situation .