Ubuntu 16.04安装openssh-server后，使用ssh客户端连接时可能报此错误，情况如下图所示：
server responded "algorithm negotiation failed”
修改服务器端ssh的配置文件，目录为：/etc/ssh/sshd_config，输入如下命令进行编辑
sudo vi /etc/ssh/sshd_config
切换编辑模式（i），设置参数
PasswordAuthentication yes
在配置文件末尾添加
Ciphers aes128-cbc,aes192-cbc,aes256-cbc,aes128-ctr,aes192-ctr,aes256-ctr,3des-cbc,arcfour128,arcfour256,arcfour,blowfish-cbc,cast128-cbc
MACs hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-ripemd160,hmac-sha1-96,hmac-md5-96
KexAlgorithms diffie-hellman-group1-sha1,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group-exchange-sha256,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group1-sha1,curve25519-sha256@libssh.org
重启sshd服务后，ssh客户端重新连接成功
sudo service ssh restart