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https://issues.apache.org/jira/browse/SSHD-942?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16934118#comment-16934118
]
Goldstein Lyor commented on SSHD-942:
-------------------------------------
Let's start with something simple - log as warning (or INFO or whatever) and
then return {{null}}. If it solves the immediate problem, then you can start
thinking about refining its behavior:
{code:java}
SshServer server = ... prepare server...
server.setUnknownChannelReferenceHandler(new UnknownChannelReferenceHandler() {
@Override
public Channel handleUnknownChannelCommand(ConnectionService service, byte
cmd, int channelId, Buffer buffer) throws IOException {
...log...
return null;
}
});
server.start();
> SSH session crashes on high latency network
> -------------------------------------------
>
> Key: SSHD-942
> URL: https://issues.apache.org/jira/browse/SSHD-942
> Project: MINA SSHD
> Issue Type: Bug
> Affects Versions: 1.7.0, 2.0.0, 2.3.0
> Reporter: David Ostrovsky
> Priority: Major
>
> Gerrit users report problem: [1] with {{git clone/fetch/pull}} operations on
> high latency network, after upgrading Gerrit to 2.16.x from 2.15.x that
> effectively means upgrade of SSHD from 1.6.0 to 1.7.0 and to 2.0.0.
> The error on SSHD 2.0.0 (Gerrit 2.16) is:
> {noformat}
> [2019-09-16 10:27:14,256] [sshd-SshServer[24facb47]-nio2-thread-8] WARN
> org.apache.sshd.server.session.ServerSessionImpl :
> exceptionCaught(ServerSessionImpl[usexxx@/172.x.x.1:63306])[state=Opened]
> SshChannelNotFoundException: Received SSH_MSG_CHANNEL_WINDOW_ADJUST on
> unknown channel 0
> {noformat}
> Note that the attempt to upgrade SSHD in Gerrit to 2.3.0 in this CL: [2],
> didn't fix the problem:
> {noformat}
> [2019-09-17 14:05:27,923] [sshd-SshDaemon[189c6683](port=22)-nio2-thread-4]
> WARN org.apache.sshd.server.session.ServerSessionImpl :
> exceptionCaught(ServerSessionImpl[<username>@/<ip>:55212])[state=Opened]
> SshChannelNotFoundException: Received SSH_MSG_CHANNEL_WINDOW_ADJUST on
> unknown channel 3
> [2019-09-17 14:05:27,924] [SSH git-upload-pack <repo> (<username>)] ERROR
> com.google.gerrit.sshd.BaseCommand : Internal server error (user <username>
> account 1000190) during git-upload-pack '<repo path>'
> org.apache.sshd.common.channel.WindowClosedException: Already closed:
> Window[server/remote](ChannelSession[id=2,
> recipient=6]-ServerSessionImpl[<username>@/<ip>:55212])
> at org.apache.sshd.common.channel.Window.waitForCondition(Window.java:302)
> at org.apache.sshd.common.channel.Window.waitForSpace(Window.java:252)
> {noformat}
> Also note, that downgrade to 1.7.0: [3] didn't fix the problem either. Only
> after downgrade to SSH 1.6.0: [4] the problem disappeared, and only warnings
> left in the log:
> {noformat}
> [2019-09-18 09:24:52,755] [NioProcessor-2] WARN
> org.apache.sshd.server.session.ServerConnectionService : Received
> SSH_MSG_CHANNEL_CLOSE on unknown channel 12
> [2019-09-18 09:24:52,756] [NioProcessor-2] WARN
> org.apache.sshd.server.session.ServerConnectionService : Received
> SSH_MSG_CHANNEL_CLOSE on unknown channel 13
> [2019-09-18 09:25:02,576] [NioProcessor-2] WARN
> org.apache.sshd.server.session.ServerConnectionService : Received
> SSH_MSG_CHANNEL_CLOSE on unknown channel 15
> [2019-09-18 09:25:36,508] [NioProcessor-2] WARN
> org.apache.sshd.server.session.ServerConnectionService : Received
> SSH_MSG_CHANNEL_CLOSE on unknown channel 18
> [2019-09-18 09:25:57,527] [NioProcessor-2] WARN
> org.apache.sshd.server.session.ServerConnectionService : Received
> SSH_MSG_CHANNEL_CLOSE on unknown channel 19
> [2019-09-18 09:30:16,488] [NioProcessor-2] WARN
> org.apache.sshd.server.session.ServerConnectionService : Received
> SSH_MSG_CHANNEL_CLOSE on unknown channel 21
> {noformat}
> [1]
> [https://bugs.chromium.org/p/gerrit/issues/detail?id=11491|https://bugs.chromium.org/p/gerrit/issues/detail?id=11491&;]
> [2] [https://gerrit-review.googlesource.com/c/gerrit/+/207752]
> [3] [https://gerrit-review.googlesource.com/c/gerrit/+/237730]
> [4] [https://gerrit-review.googlesource.com/c/gerrit/+/237731]
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