Andrew C created SSHD-207:
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Summary: CLONE - Direct TCP/IP Port Forward sends EOF to client
after closing channel
Key: SSHD-207
URL: https://issues.apache.org/jira/browse/SSHD-207
Project: MINA SSHD
Issue Type: Bug
Affects Versions: 0.6.0
Reporter: Andrew C
Assignee: Guillaume Nodet
Fix For: 0.7.0
While testing port forwarding from an OpenSSH_5.8p2 client to a MINA SSHD
server, I noticed that after the first disconnection of a client from the
forwarded port, the entire SSH session would be disconnected. The client
command I ran was:
ssh -N -L 60443:<target>:443 -p 50022 tester@<minasshd>
Looking at the traces, I saw the following from SSHD:
13:54:12.823 [NioProcessor-1] DEBUG o.a.s.server.session.ServerSession -
Received packet SSH_MSG_CHANNEL_OPEN
13:54:12.823 [NioProcessor-1] INFO o.a.s.server.session.ServerSession -
Received SSH_MSG_CHANNEL_OPEN direct-tcpip
13:54:12.826 [NioProcessor-1] INFO o.a.s.s.channel.ChannelDirectTcpip -
Receiving request for direct tcpip: hostToConnect=<target>, portToConnect=443,
originatorIpAddress=127.0.0.1, originatorPort=54145
13:54:15.588 [NioProcessor-1] DEBUG o.a.s.server.session.ServerSession -
Received packet SSH_MSG_CHANNEL_EOF
13:54:15.589 [NioProcessor-1] INFO o.a.s.s.channel.ChannelDirectTcpip -
Received SSH_MSG_CHANNEL_EOF on channel 0
13:54:15.589 [NioProcessor-1] INFO o.a.s.s.channel.ChannelDirectTcpip - Send
SSH_MSG_CHANNEL_CLOSE on channel 0
13:54:15.590 [NioProcessor-1] DEBUG o.a.s.server.session.ServerSession -
Received packet SSH_MSG_CHANNEL_CLOSE
13:54:15.590 [NioProcessor-1] INFO o.a.s.s.channel.ChannelDirectTcpip -
Received SSH_MSG_CHANNEL_CLOSE on channel 0
13:54:15.590 [NioProcessor-1] INFO o.a.s.s.channel.ChannelDirectTcpip -
Closing channel 0 immediately
13:54:15.591 [NioProcessor-1] INFO o.a.s.s.channel.ChannelDirectTcpip -
Closing channel 0 immediately
13:54:15.593 [NioProcessor-26] INFO o.a.s.s.channel.ChannelDirectTcpip - Send
SSH_MSG_CHANNEL_EOF on channel 0
13:54:15.595 [NioProcessor-1] DEBUG o.a.s.server.session.ServerSession -
Received packet SSH_MSG_DISCONNECT
13:54:15.595 [NioProcessor-1] INFO o.a.s.server.session.ServerSession -
Received SSH_MSG_DISCONNECT (reason=2, msg=Received ieof for nonexistent
channel 2.)
13:54:15.595 [NioProcessor-1] INFO o.a.s.server.session.ServerSession -
Closing session
13:54:15.595 [NioProcessor-1] DEBUG o.a.s.server.session.ServerSession -
Closing IoSession
13:54:15.596 [NioProcessor-1] DEBUG o.a.s.server.session.ServerSession -
IoSession closed
So if I read this right, the client sends an EOF, then the server sends a
CLOSE, then the client sends a CLOSE. After all of this, the server sends back
an EOF, but the channel no longer exists at the client, which causes a
disconnection.
I looked into the source code, and figured the following change might correct
the issue:
Index:
sshd-core/src/main/java/org/apache/sshd/server/channel/ChannelDirectTcpip.java
===================================================================
---
sshd-core/src/main/java/org/apache/sshd/server/channel/ChannelDirectTcpip.java
(revision 1207930)
+++
sshd-core/src/main/java/org/apache/sshd/server/channel/ChannelDirectTcpip.java
(working copy)
@@ -109,7 +109,9 @@
@Override
public void sessionClosed(IoSession session) throws Exception {
+ if (!closing) {
sendEof();
+ }
}
};
connector.setHandler(handler);
It appears to work, but I do not know if it is correct, or if it will break
other situations. Can anyone comment on it?
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