2019-11-01 17:32:08 发布

嵌入式linux使用dropbear遇到的免密登陆失败问题
至于如何实现免密登陆，只需把登陆方的id_rsa.pub添加到服务器的authorized_keys即可
详细可参考其它内容
此记录下解决问题的过程
1. 用ssh -vvv root@192.168.1.1 查看，有如下记录
debug3: authmethod_is_enabled publickey
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /home/hjj/.ssh/id_rsa
debug3: send_pubkey_test
debug3: send packet: type 50
debug2: we sent a publickey packet, wait for reply
debug3: receive packet: type 51
debug1: Authentications that can continue: publickey,password
debug1: Trying private key: /home/hjj/.ssh/id_dsa
debug3: no such identity: /home/hjj/.ssh/id_dsa: No such file or directory
debug1: Trying private key: /home/hjj/.ssh/id_ecdsa
debug3: no such identity: /home/hjj/.ssh/id_ecdsa: No such file or directory
debug1: Trying private key: /home/hjj/.ssh/id_ed25519
debug3: no such identity: /home/hjj/.ssh/id_ed25519: No such file or directory
debug2: we did not send a packet, disable method
debug3: authmethod_lookup password
debug3: remaining preferred: ,password
debug3: authmethod_is_enabled password
debug1: Next authentication method: password
root@192.168.1.1's password:

2. 查看服务器log 记录
dropbear[28567]: Child connection from 192.168.1.99:55754
dropbear[28567]: /root must be owned by user or root, and not writable by others

3.查看/root 目录
drwx------    4 dbus     dbus         728 Aug 28  2018 root/

原来正如log 所指出的，/root 属主和组是错误的， 修改/root 的用户和组
chown root:root /root

drwx------    4 root     root         728 Aug 28  2018 root/

问题解决，可以免密登陆了, 甚好！
解决此问题也走了不少弯路，故写此纪念. 没想到免密登陆,拷贝等与用户的组和属主有关系，不看log是发现不了的。

还碰到一次 ubuntu 免密登陆不了centos, 通过观察log, 发现问题,具体是什么完了，也是目录属性问题, 原来是/root目录设置的是777 权限, 改成755权限, 实现了免密登陆!!!