无法通过SSH连接Linux开发板（Dropbear服务）求助

我使用运行Dropbear SSH服务器的Linux开发板，该开发板通过以太网连接本地路由器，ip a命令可正常执行。在Windows 10系统的VMware虚拟机中安装了Ubuntu 16.04并部署OpenSSH，执行命令ssh root@192.168.30.202尝试连接开发板时失败，报错信息：

ssh: connect to host 192.168.30.202 port 22: Connection refused

已在两台设备（笔记本、台式机）上测试，更换VMware所有网络模式后问题依旧。

开发板SSH客户端（Dropbear）信息 #

root@myd-y6ull14x14:~# ssh
Dropbear SSH client v2019.78 https://matt.ucc.asn.au/dropbear/dropbear.html
Usage: ssh [options] [user@]host[/port][,[user@]host/port],...] [command]
-p <remoteport>
-l <username>
-t    Allocate a pty
-T    Don't allocate a pty
-N    Don't run a remote command
-f    Run in background after auth
-y    Always accept remote host key if unknown
-y -y Don't perform any remote host key checking (caution)
-s    Request a subsystem (use by external sftp)
-o option     Set option in OpenSSH-like format ('-o help' to list options)
-i <identityfile>   (multiple allowed, default .ssh/id_dropbear)
-A    Enable agent auth forwarding
-L <[listenaddress:]listenport:remotehost:remoteport> Local port forwarding
-g    Allow remote hosts to connect to forwarded ports
-R <[listenaddress:]listenport:remotehost:remoteport> Remote port forwarding
-W <receive_window_buffer> (default 24576, larger may be faster, max 1MB)
-K <keepalive>  (0 is never, default 0)
-I <idle_timeout>  (0 is never, default 0)
-B <endhost:endport> Netcat-alike forwarding
-J <proxy_program> Use program pipe rather than TCP connection
-c <cipher list> Specify preferred ciphers ('-c help' to list options)
-m <MAC list> Specify preferred MACs for packet verification (or '-m help')
-b    [bind_address][:bind_port]
-V    Version

开发板ip a输出 #

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: can0: <NOARP,ECHO> mtu 16 qdisc noop state DOWN group default qlen 10
    link/can 
3: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 0a:df:74:e2:6f:39 brd ff:ff:ff:ff:ff:ff
    inet 192.168.30.202/24 brd 192.168.30.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::8df:74ff:fee2:6f39/64 scope link 
       valid_lft forever preferred_lft forever
4: eth1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
    link/ether ee:e1:a2:03:a9:fb brd ff:ff:ff:ff:ff:ff
5: sit0@NONE: <NOARP> mtu 1480 qdisc noop state DOWN group default qlen 1000
    link/sit 0.0.0.0 brd 0.0.0.0

排查建议 #

• 确认开发板Dropbear SSH服务端是否运行：执行ps | grep dropbear，若无进程则启动服务（如/etc/init.d/dropbear start或systemctl start dropbear）
• 检查Dropbear监听端口：执行netstat -tulpn | grep dropbear，确认监听0.0.0.0:22或:::22（而非仅本地回环接口）
• 验证网络连通性：在Ubuntu中执行ping 192.168.30.202，若不通则先解决网段匹配、路由器隔离问题
• 检查开发板防火墙：执行iptables -L，若存在拒绝22端口规则，添加允许：iptables -A INPUT -p tcp --dport 22 -j ACCEPT
• 尝试指定端口连接：查看开发板Dropbear配置文件（如/etc/default/dropbear）确认端口，执行ssh -p <端口号> root@192.168.30.202
• 查看服务日志：在开发板执行dmesg | grep dropbear或cat /var/log/messages | grep dropbear，排查启动或连接失败原因

内容的提问来源于stack exchange，提问作者HarryTra