SFTP upload error: com.jcraft.jsch JSchException: connection is closed by foreign host

By default ,SSH The number of connections is This configuration ：

MaxStartups The default setting is 10:30:60  It means ： From 10 Connections begin with 30% Probability （ Increasing ） Reject new connection , Until the number of connections reaches 60 until .

So when the number of connections becomes larger , The failure rate will become very high .

1) modify /etc/ssh/sshd_config Medium MaxStartups, Change it to MaxStartups 100:30:500

Restart the service , stay centos7 in ：service   sshd restart

Problem solving ！ It can support high concurrency connections .