Axway XFB sftp server & no-more-sessions at openssh.com

[Damien Miller]

On Tue, 18 Nov 2008, Partenie, Sergiu wrote:

> Hello all,
>
> First of all, thank you for such great software.
>
> I have a bug (and a fix) to report for 5.1p:
>
> The "Axway XFB.Gateway" SFTP server will drop sftp sessions
> initiated from the OpenSSH 5.1p (HP-UX) sftp if it receives the
> "no-more-sessions at openssh.com" flag It can be reproduced also with the
> sftp sessions initiated from a OpenSSH 5.1p sftp on a Linux machine
>
> As a workaround we are using now "-oControlMaster=yes" for
> each sftp connection in order to disable the sending of
> "no-more-sessions at openssh.com" flag.
>
> Can you please add for future versions in "compat.c" that for
> connections to servers who identify themselves as "XFB.Gateway Unix" a
> flag should be set that "no-more-sessions at openssh.com" is not sent to
> that server ?

Due to bugs in other servers, OpenSSH 5.2 will not send this extension
message (nor the eow at openssh.com channel half-closed notification) to
any server that doesn't identify itself as OpenSSH. Vendors are required
to gracefully refuse messages that they do not understand, so the "Axway
XFB.Gateway" is actually what is at fault here.

If any other ssh vendors what to receive these messages, then they should
let us know so they can be whitelisted in compat.c

-d