IOException (Broken pipe) on a socket local forwarding channel causes SSH client-server connection down

Hi,

I have a problem with local port forwarding mechanism implemented in Apache SSHD.

In my company we successfully use Apache SSHD library for secure local socket forwarding protocols.

When on a local port forwarding channel an IOException (Broken pipe) happen for some reason (network, etc...), the SSH client server is being disconnected abruptly.

I'm not convinced this is the right behavior. I think it is not necessary to bring down SSH client server connection because this is not a protocol violation, but a socket problem related to forwarded remote server connection.

Please, can you comment about this issue ?

Follow an excerpt of the traces :

2018-01-23 10:30:10,017 DEBUG [sshd-SshServer[1786f9d5]-nio2-thread-2       ] [Nio2Session.handleWriteCycleFailure] handleWriteCycleFailure(Nio2Session[local=/192.168.180.70:38957, remote=/192.168.10.31:36228]) failed (IOException) to write 32768 bytes: Broken pipe
2018-01-23 10:30:10,017 DEBUG [sshd-SshServer[1786f9d5]-nio2-thread-3       ] [Window.waitForSpace] waitForSpace(Window[server/remote](TcpipServerChannel[id=662, recipient=11]-ServerSessionImpl[circessh@/192.168.190.2:14840])) available: 1146880
2018-01-23 10:30:10,017 DEBUG [sshd-SshServer[1786f9d5]-nio2-thread-2       ] [TcpipServerChannel.handleWriteDataFailure] handleWriteDataFailure(TcpipServerChannel[id=662, recipient=11]-ServerSessionImpl[circessh@/192.168.190.2:14840])[SSH_MSG_CHANNEL_DATA] failed (IOException) to write len=32768: Broken pipe
2018-01-23 10:30:10,018 WARN  [sshd-SshServer[1786f9d5]-nio2-thread-2       ] [AbstractSession.exceptionCaught] exceptionCaught(ServerSessionImpl[circessh@/192.168.190.2:14840])[state=Opened] IOException: Broken pipe
2018-01-23 10:30:10,018 DEBUG [sshd-SshServer[1786f9d5]-nio2-thread-3       ] [Window.waitAndConsume] waitAndConsume(Window[server/remote](TcpipServerChannel[id=662, recipient=11]-ServerSessionImpl[circessh@/192.168.190.2:14840])) - requested=32768, available=1146880
2018-01-23 10:30:10,018 DEBUG [sshd-SshServer[1786f9d5]-nio2-thread-2       ] [AbstractSession.exceptionCaught] exceptionCaught(ServerSessionImpl[circessh@/192.168.190.2:14840])[state=Opened] details
java.io.IOException: Broken pipe
        at sun.nio.ch.FileDispatcherImpl.write0(Native Method)
        at sun.nio.ch.SocketDispatcher.write(SocketDispatcher.java:47)
        at sun.nio.ch.IOUtil.writeFromNativeBuffer(IOUtil.java:93)
        at sun.nio.ch.IOUtil.write(IOUtil.java:65)
        at sun.nio.ch.UnixAsynchronousSocketChannelImpl.finishWrite(UnixAsynchronousSocketChannelImpl.java:582)
        at sun.nio.ch.UnixAsynchronousSocketChannelImpl.finish(UnixAsynchronousSocketChannelImpl.java:195)
        at sun.nio.ch.UnixAsynchronousSocketChannelImpl.onEvent(UnixAsynchronousSocketChannelImpl.java:213)
        at sun.nio.ch.EPollPort$EventHandlerTask.run(EPollPort.java:293)
        at java.lang.Thread.run(Thread.java:745)
2018-01-23 10:30:10,023 DEBUG [sshd-SshServer[1786f9d5]-nio2-thread-1       ] [Nio2Session.writePacket] writePacket(Nio2Session[local=/192.168.180.70:45470, remote=/192.168.10.31:22]) Writing 24780 bytes
2018-01-23 10:30:10,025 DEBUG [sshd-SshServer[1786f9d5]-nio2-thread-2       ] [SessionTimeoutListener.sessionException] sessionException(ServerSessionImpl[circessh@/192.168.190.2:14840]) IOException: Broken pipe