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Posted to dev@mina.apache.org by "Goldstein Lyor (JIRA)" <ji...@apache.org> on 2018/02/01 18:00:00 UTC

[jira] [Updated] (SSHD-800) Numerous SSH_MSG_CHANNEL_FAILURE messages sent for

     [ https://issues.apache.org/jira/browse/SSHD-800?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Goldstein Lyor updated SSHD-800:
--------------------------------
    Summary: Numerous SSH_MSG_CHANNEL_FAILURE messages sent for   (was: SSHD port forwarding. Wrong SSH_MSG_CHANNEL_FAILURE)

> Numerous SSH_MSG_CHANNEL_FAILURE messages sent for 
> ---------------------------------------------------
>
>                 Key: SSHD-800
>                 URL: https://issues.apache.org/jira/browse/SSHD-800
>             Project: MINA SSHD
>          Issue Type: Bug
>    Affects Versions: 1.7.0
>            Reporter: Fulvio Cavarretta
>            Priority: Major
>
> Hi in case the SSHD server receives a message for a not existing channel, it sends back a _SSH_MSG_CHANNEL_FAILURE_.
> This behaviour is not described in RFC4254, which, I agree, is unclear about what should be do in this case.
> Since the current SSHD implementation send back a _SSH_MSG_CHANNEL_FAILURE_ message (with the local channel id), in our environment, it put the receipient in an inconsistent state. 
> In out enviroment happened that the receipient has sent a _SSH_MSG_CHANNEL_DATA_ while SSHD had already closed the channel.
> I fully agree that this should not happen (I will open another issue about this) but the _SSH_MSG_CHANNEL_FAILURE_ further complicates things.
>  
> The problem can be overcome modifying line 78 of _org.apache.sshd.common.session.helpers.DefaultUnknownChannelReferenceHandler_
>  
> letting
> {code:java}
> case SshConstants.SSH_MSG_CHANNEL_EXTENDED_DATA:
> // Not sure if entirely compliant with RFC4254, but try to stem the flood	
> wantReply = false;
> break;
> default: // do nothing{code}
>  
> instead of
>  
> {code:java}
> case SshConstants.SSH_MSG_CHANNEL_EXTENDED_DATA:
> // Not sure if entirely compliant with RFC4254, but try to stem the flood	
> wantReply = true;
> break;
> default: // do nothing{code}



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