Docker centos7 安装ssh
参考：
http://www.thinksaas.cn/topics/0/516/516528.html
docker run -i -t centos:7 /bin/bash
yum install passwd openssl openssh-server -y
ssh-keygen -q -t rsa -b 2048 -f /etc/ssh/ssh_host_rsa_key -N ''
ssh-keygen -q -t ecdsa -f /etc/ssh/ssh_host_ecdsa_key -N ''
ssh-keygen -t dsa -f /etc/ssh/ssh_host_ed25519_key -N ''
sed -i "s/#UsePrivilegeSeparation.*/UsePrivilegeSeparation no/g" /etc/ssh/sshd_config
sed -i "s/UsePAM.*/UsePAM no/g" /etc/ssh/sshd_config
/usr/sbin/sshd -D
