启动sshd时,报“Could not load host key”错

原文发表于cu:2016-05-24

现象:启动sshd服务时,虽看似服务启动成功,但客户端并不能连接上sshd服务器端。如下:

[root@aefe8007a17d ~]# /usr/sbin/sshd
Could not load host key: /etc/ssh/ssh_host_rsa_key
Could not load host key: /etc/ssh/ssh_host_ecdsa_key
Could not load host key: /etc/ssh/ssh_host_ed25519_key

原因:
1. 从提示信息看是sshd守护进程不能加载主机密钥文件,因为找不到这些密钥文件(配置文件/etc/ssh/sshd_config中已定义密钥文件名与路径);
2. 一般openssh服务正常安装后,主机会自动生成相应的主机密钥文件,但这里因未知原因并没有完成这一步动作,导致无法远程ssh连接。
ps:检查密钥文件是否存在(还有一种现象为:密钥文件存在,但文件大小为0):

[root@aefe8007a17d ~]# ll /etc/ssh/
total 252
-rw-r--r-- 1 root root 242153 Mar 21 22:18 moduli
-rw-r--r-- 1 root root 2208 Mar 21 22:18 ssh_config
-rw------- 1 root root 4361 Mar 21 22:18 sshd_config

解决方案,重新生成主机密钥文件:
1. 生成rsa_key (-t表示生成的密钥所使用的加密类型;-f项后接要生成的密钥文件名);

[root@aefe8007a17d ~]# ssh-keygen -t rsa -f /etc/ssh/ssh_host_rsa_key
Generating public/private rsa key pair.
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /etc/ssh/ssh_host_rsa_key.
Your public key has been saved in /etc/ssh/ssh_host_rsa_key.pub.
The key fingerprint is:
5e:2d:19:51:b1:e3:e0:60:65:53:e4:14:f8:d8:38:af root@aefe8007a17d
The key's randomart image is:
+--[ RSA 2048]----+
| ==Bo |
| o.= . |
| o o=+ |
| . o+*o. |
| S =oo |
| . . .. |
| . . |
| E |
| |
+-----------------+
[root@aefe8007a17d ~]# ssh-keygen -t ecdsa -f /etc/ssh/ssh_host_ecdsa_key

2. 生成ecdsa_key;

[root@aefe8007a17d ~]# ssh-keygen -t ecdsa -f /etc/ssh/ssh_host_ecdsa_key

3. 生成ed25519_key。

[root@aefe8007a17d ~]# ssh-keygen -t ed25519 -f /etc/ssh/ssh_host_ed25519_key

验证:

1. 再次检查密钥文件是否存在且合规,可以看到已生成相应主机密钥文件(实际上主机密钥文件为私钥,.pub文件为公钥):

[root@aefe8007a17d ~]# ll /etc/ssh/
total 276
-rw-r--r-- 1 root root 242153 Mar 21 22:18 moduli
-rw-r--r-- 1 root root 2208 Mar 21 22:18 ssh_config
-rw------- 1 root root 227 May 22 16:48 ssh_host_ecdsa_key
-rw-r--r-- 1 root root 179 May 22 16:48 ssh_host_ecdsa_key.pub
-rw------- 1 root root 411 May 22 16:48 ssh_host_ed25519_key
-rw-r--r-- 1 root root 99 May 22 16:48 ssh_host_ed25519_key.pub
-rw------- 1 root root 1679 May 22 16:48 ssh_host_rsa_key
-rw-r--r-- 1 root root 399 May 22 16:48 ssh_host_rsa_key.pub
-rw------- 1 root root 4361 Mar 21 22:18 sshd_config

2. 此时客户端可ssh连接上sshd服务器端:

[root@localhost ~]# ssh 172.17.0.2
The authenticity of host '172.17.0.2 (172.17.0.2)' can't be established.
ECDSA key fingerprint is 37:2a:69:46:c4:bd:92:b2:43:b4:cc:42:41:8e:12:2e.
Are you sure you want to continue connecting (yes/no)? 
posted @ 2017-08-22 10:57  Netonline  阅读(14228)  评论(0编辑  收藏  举报