指令-L AAAA:somehost:BBBB将使SSH监听 localhost (运行ssh命令的计算机)上的端口AAAA，并且通过SSH会话将与该端口的任何连接转发到主机somehost端口BBBB.因此，您需要在运行ssh命令的计算机上的浏览器中打开http://localhost:5558/.

The directive -L AAAA:somehost:BBBB will cause SSH to listen on port AAAA on localhost (the machine the ssh command is run on) and forward any connection to that port, over the SSH session, to the host somehost port BBBB. So, you need to open http://localhost:5558/ in the browser on the machine you run the ssh command on.