无法使用ssh启动端口转发

我使用以下内容在192.168.1.8上启动sshd：

sudo /usr/sbin/sshd -ddd

然后我尝试打开到192.168.1.5:1234的SSH隧道，但我无法这样做。这是sshd -ddd说：

debug1: server_input_channel_open: confirm direct-tcpip
debug3: channel 1: waiting for connection
debug1: channel 1: connected to 192.168.1.5 port 1234
debug2: channel 1: read<=0 rd 10 len 0
debug2: channel 1: read failed
debug2: channel 1: close_read
debug2: channel 1: input open -> drain
debug2: channel 1: ibuf empty
debug2: channel 1: send eof
debug2: channel 1: input drain -> closed
debug2: channel 1: rcvd close
debug2: channel 1: output open -> drain
debug3: channel 1: will not send data after close
debug2: channel 1: obuf empty
debug2: channel 1: close_write
debug2: channel 1: output drain -> closed
debug2: channel 1: send close
debug2: channel 1: is dead
debug2: channel 1: garbage collecting
debug1: channel 1: free: direct-tcpip, nchannels 2
debug3: channel 1: status: The following connections are open:
  #0 server-session (t4 r256 i0/0 o0/0 fd 11/9 cc -1)
  #1 direct-tcpip (t4 r257 i3/0 o3/0 fd 10/10 cc -1)

所以它能够连接，但读取失败。然而，当我这样做时（192.168.1.8），我能够连接（没有失败的读取）：

ssh -p 1234 username@192.168.1.5

那么为什么当192.168.1.8上的直接ssh连接没有时，隧道在192.168.1.8上失败？

我正在使用PuTTY来创建隧道。