SSH（xshell）连ubuntu出现Connection closed by foreign host

SSH（xshell）连ubuntu出现Connection closed by foreign host

 

Connection closed by foreign host....

该问题出现的原因是/etc/ssh目录下的文件的熟悉被修改了，从新修改回原始状态即可：

cd /etc/ssh

sudo chmod 644 ./*

sudo chmod 600 ssh_host_dsa_key

sudo chmod 600 ssh_host_rsa_key

sudo chmod 755 .