我对 X11 有一个困惑的问题。
我在桌面上运行 Ubuntu 19.10，从那里我可以通过 ssh 连接到服务器 A，其中 X11 转发运行良好（即我客户端上的 X11 运行正常），但另一方面，如果我尝试使用 X11 连接到另一台服务器 B，那么它就不起作用。
但实际上，服务器 B 上的 X11 没问题，因为当我通过我的笔记本电脑（安装有 Ubuntu 18.04）连接到它时，它可以工作！
这是我从中获得的信息ssh -v -X：
debug1: Requesting X11 forwarding with authentication spoofing.
debug1: Sending environment.
....
debug1: client_input_channel_open: ctype x11 rchan 2 win 65536 max 16384
debug1: client_request_x11: request from 127.0.0.1 49834
debug1: channel 1: new [x11]
debug1: confirm x11
debug1: client_input_channel_open: ctype x11 rchan 3 win 65536 max 16384
debug1: client_request_x11: request from 127.0.0.1 49860
debug1: channel 2: new [x11]
debug1: confirm x11
debug1: client_input_channel_open: ctype x11 rchan 4 win 65536 max 16384
debug1: client_request_x11: request from 127.0.0.1 49878
debug1: channel 3: new [x11]
debug1: confirm x11
debug1: channel 1: FORCE input drain
这很奇怪，因为常用的解决方案（编辑/etc/ssh/ssh_config）不起作用。而使用 Ubuntu 18.04，一切都开箱即用！
我比较了 Ubuntu18.04@laptop 成功案例和 Ubuntu19.10@desktop 不成功案例的输出，唯一显着的区别是消息FORCE input drain。
更完整的输出ssh -vvv -X给了我这个（请注意，我正在尝试打开一个gnuplot窗口来测试 X11）：
gnuplot> p x w l
debug3: receive packet: type 90
debug1: client_input_channel_open: ctype x11 rchan 2 win 65536 max 16384
debug1: client_request_x11: request from 127.0.0.1 52382
debug2: fd 7 setting O_NONBLOCK
debug3: fd 7 is O_NONBLOCK
debug1: channel 1: new [x11]
debug1: confirm x11
debug3: send packet: type 91
debug2: channel 1: rcvd adjust 34784
debug3: receive packet: type 90
debug1: client_input_channel_open: ctype x11 rchan 3 win 65536 max 16384
debug1: client_request_x11: request from 127.0.0.1 52394
debug2: fd 8 setting O_NONBLOCK
debug3: fd 8 is O_NONBLOCK
debug1: channel 2: new [x11]
debug1: confirm x11
debug3: send packet: type 91
debug3: receive packet: type 90
debug1: client_input_channel_open: ctype x11 rchan 4 win 65536 max 16384
debug1: client_request_x11: request from 127.0.0.1 52398
debug2: fd 9 setting O_NONBLOCK
debug3: fd 9 is O_NONBLOCK
debug1: channel 3: new [x11]
debug1: confirm x11
debug3: send packet: type 91
debug2: channel 1: rcvd adjust 33588
debug2: channel 1: rcvd adjust 46612
debug2: channel 1: rcvd adjust 37976
debug2: channel 1: rcvd adjust 45940
debug2: channel 1: rcvd adjust 33144
debug3: receive packet: type 96
debug2: channel 1: rcvd eof
debug2: channel 1: output open -> drain
debug2: channel 1: obuf empty
debug2: channel 1: chan_shutdown_write (i0 o1 sock 7 wfd 7 efd -1 [closed])
debug2: channel 1: output drain -> closed
debug1: channel 1: FORCE input drain
debug2: channel 1: ibuf empty
debug2: channel 1: send eof
debug3: send packet: type 96
debug2: channel 1: input drain -> closed
debug2: channel 1: send close
debug3: send packet: type 97
debug3: channel 1: will not send data after close
debug3: channel 1: will not send data after close
Warning: slow font initialization
debug3: channel 1: will not send data after close
debug3: channel 1: will not send data after close
gnuplot>
debug3: channel 1: will not send data after close
有人知道这是什么吗？也许是 Ubuntu 19.10 中的一些错误？