在docker中开启sshd操作

首先在docker中安装openssh-server,安装完毕后切换到openssh-server的安装目录/etc/ssh下面。

运行ssh-keygen生成对应的密钥。

先看看sshd的配置文件sshd_config，里面有如下内容：

hostkey /etc/ssh/ssh_host_rsa_key
#hostkey /etc/ssh/ssh_host_dsa_key
hostkey /etc/ssh/ssh_host_ecdsa_key
hostkey /etc/ssh/ssh_host_ed25519_key

有rsa,dsa,ecdsa,ed25519的加密方式，根据这几种加密方式来生成对应的密钥对。

[root@655f62a4ed82 ssh]# ssh-keygen -t rsa //生成rsa
generating public/private rsa key pair.
enter file in which to save the key (/root/.ssh/id_rsa): 
enter passphrase (empty for no passphrase): 
enter same passphrase again: 
your identification has been saved in /root/.ssh/id_rsa.
your public key has been saved in /root/.ssh/id_rsa.pub.
the key fingerprint is:
0e:fa:07:36:bb:87:c1:60:14:be:41:41:01:1b:4b:bc root@655f62a4ed82
the key's randomart image is:
+--[ rsa 2048]----+
| .+o*+      |
| ..*.      |
| ooo      |
| e oo      |
|  ..o. s    |
|   .*o     |
|  .. *.    |
|   .o o    |
|   o+     |
+-----------------+
[root@655f62a4ed82 ssh]# ssh-keygen -t dsa //生成dsa
generating public/private dsa key pair.
enter file in which to save the key (/root/.ssh/id_dsa): 
enter passphrase (empty for no passphrase): 
enter same passphrase again: 
your identification has been saved in /root/.ssh/id_dsa.
your public key has been saved in /root/.ssh/id_dsa.pub.
the key fingerprint is:
ee:8c:db:a8:24:68:0d:33:79:eb:09:33:ed:74:c3:66 root@655f62a4ed82
the key's randomart image is:
+--[ dsa 1024]----+
|         |
|         |
|         |
| .       |
| = .  s    |
| .b o .     |
|.=.=.e .    |
|. bo= .*     |
|  +..+.+    |
+-----------------+
[root@655f62a4ed82 ssh]# ssh-keygen -t ecdsa //生成ecdsa
generating public/private ecdsa key pair.
enter file in which to save the key (/root/.ssh/id_ecdsa): 
enter passphrase (empty for no passphrase): 
enter same passphrase again: 
your identification has been saved in /root/.ssh/id_ecdsa.
your public key has been saved in /root/.ssh/id_ecdsa.pub.
the key fingerprint is:
84:74:de:d1:e4:98:a1:5c:27:25:8e:b7:d6:27:fd:c9 root@655f62a4ed82
the key's randomart image is:
+--[ecdsa 256]---+
|   . . *++  |
|   . = * x.  |
|   . * * .  |
|    . . o .  |
|    s o o o |
|     .  o...|
|        e.|
|         |
|         |
+-----------------+
[root@655f62a4ed82 ssh]# ssh-keygen -t ed25519
generating public/private ed25519 key pair.
enter file in which to save the key (/root/.ssh/id_ed25519): 
enter passphrase (empty for no passphrase): 
enter same passphrase again: 
your identification has been saved in /root/.ssh/id_ed25519.
your public key has been saved in /root/.ssh/id_ed25519.pub.
the key fingerprint is:
d8:40:95:1f:07:96:8a:83:7f:af:19:01:3b:b4:79:91 root@655f62a4ed82
the key's randomart image is:
+--[ed25519 256--+
|   ....oo   |
|   . .oo .  |
|   .+.eo o   |
|  ..oo...   |
|   .*.s    |
|   .o..    |
|    ...    |
|     o.   |
|    o.    |
+-----------------+
[root@655f62a4ed82 ssh]# cp ~/.ssh/id_rsa.pub ~/.ssh/authorized_keys 

密钥对生成完毕后，需要修改sshd_config中上述文件所在的位置的。

hostkey /root/.ssh/id_rsa
hostkey /root/.ssh/id_dsa
hostkey /root/.ssh/id_ecdsa
hostkey /root/.ssh/id_ed25519

运行/usr/sbin/sshd,查看22端口号是否开启，开启说明启动成功。

[root@655f62a4ed82 ssh]# /usr/sbin/sshd
[root@655f62a4ed82 ssh]# lsof -i:22
command pid user  fd  type device size/off node name
sshd   37 root  3u ipv4 250907   0t0 tcp *:ssh (listen)
sshd   37 root  4u ipv6 250909   0t0 tcp *:ssh (listen)

补充知识：docker容器内运行sshd进程，远程登录闪退(exit status 254)

注：

背景

在容器内运行了一个sshd进程，映射出一个端口供外部远程连接。可以每次连接的时候，输入密码后立即就退出了，现象如下：

[root@localhost /]# ssh root@192.168.0.6 -p 8000
root@192.168.0.6's password: 
last login: tue nov 6 14:46:17 2018 from 192.168.0.6
connection to 192.168.0.6 closed.

查看调试信息，最后退出的打印如下：

......
connection to 192.168.0.6 closed.
transferred: sent 2264, received 2224 bytes, in 0.0 seconds
bytes per second: sent 235367.6, received 231209.1
debug1: exit status 254

分析

从打印来看，已经有last login的信息，所以密码肯定是输入正确的，也已经登录系统，那就是在初始化的环境的时候跪了。首先考虑了hosts.deny的配置，注释相关配置后问题依旧。

网上有说注释sshd配置文件中的usepam配置，也就是不使用pam鉴权模块，

#usepam yes

修改完重启sshd进程，这下果然可以了。至于原因，清一色的说是什么默认配置下，启用了超时断开连接功能。这就是在扯，默认的链接断开时间不可能这么短，而且为什么在非docker环境下sshd进程运行是正常的。我是不接受这个理由的。那就再看看呗。不使用pam鉴权就没问题，于是又挨个把/etc/pam.d/里和sshd相关的配置一个一个注释，还是没发现问题所在。

这时想到可以看看pam的日志，应该有些提示吧。顺带提一下， redhat和centos的pam日志存放在/var/log/secure中，ubuntu和debian在 /var/log/auth.log中存储认证信息。

果然，pam里有错误信息，

nov 6 15:36:56 bbb sshd[11016]: accepted password for root from 192.168.0.6 port 56394 ssh2
nov 6 15:36:56 bbb sshd[11016]: pam_limits(sshd:session): could not set limit for 'nproc': operation not permitted
nov 6 15:36:56 bbb sshd[11016]: pam_limits(sshd:session): could not set limit for 'nofile': operation not permitted
nov 6 15:36:56 bbb sshd[11016]: pam_limits(sshd:session): could not set limit for 'memlock': operation not permitted
nov 6 15:36:56 bbb sshd[11016]: pam_unix(sshd:session): session opened for user root by (uid=0)
nov 6 15:36:56 bbb sshd[11016]: error: pam: pam_open_session(): permission denied
nov 6 15:36:56 bbb sshd[11016]: received disconnect from 192.168.0.6: 11: disconnected by user

可见，这是由于设置nproc、nofile、memlock等参数权限不够而导致，而这些配置是在pam组件里，由以下两个文件保存配置，

/etc/security/limits.conf

/etc/security/limits.d/90-nproc.conf

将这两个文件里面的相关设置注释，打开pam鉴权，ssh连接成功了。这才是问题所在。

另外还有其他方法

1、因为是由于权限不够导致，那就在启动容器的时候带上--privileged参数，使用特权用户，同样可以解决该问题

2、因为是在配置ulimits时错误，那么可以在启动容器时使用--ulimit=[]参数来配置

以上这篇在docker中开启sshd操作就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持。