[SOLVED] CentOS 7.4 with updated 4.4 kernel needs SMB 2.1

[jimj]

I also posted this here:
https://www.linuxquestions.org/question ... ost5772016

With CentOS 7.4 using its stock kernel "kernel-3.10.0-693.2.2.el7" I could successfully mount a Windows 10 Pro version 1703 share with a command like this:

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mount -t cifs //127.1.2.3/myshare /mnt/mymount -o user=william,pass=gates,vers=3.0 -rw

After upgrading my kernel to "kernel-lt-4.4.93-1.el7.elrepo.x86_64" the mount command above gave this error:

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mount error(5): Input/output error

I could still connect with smbclient like this:

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smbclient //127.1.2.3/myshare -U william%gates -m SMB3

By running 'dmesg' I was able to see another error message that appeared before the unhelpful "mount error(5): Input/output error" message. The these two messages always appeared in pairs:

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[root@novell bill]# dmesg
[ 7658.616374] CIFS VFS: validate protocol negotiate failed: -11
[ 7658.616563] CIFS VFS: cifs_mount failed w/return code = -5

Googling for the first error message (CIFS VFS: validate protocol negotiate failed: -11) lead me to this bug report:
https://bugzilla.redhat.com/show_bug.cgi?id=1502606
which had the workaround. Using version 2.1 instead of 3.0 solved the problem. This is the mount command that now works for me:

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mount -t cifs //127.1.2.3/myshare /mnt/mymount -o user=william,pass=gates,vers=2.1 -rw

As an added bonus SMB version 2.1 also works with the stock kernel-3.10.0-693.2.2.el7.

[toracat]

Thanks for the heads up. While non-CentOS kernels are not supported here, your info would help others using newer kernels like kernel-lt/ml.

[toracat]

And CentOS's own kernel v4.9 is also affected.

[jimj]

And CentOS's own kernel v4.9 is also affected.

I wasn't aware CentOS had a 4.9 kernel. Is this available via a yum repo?

[toracat]

I wasn't aware CentOS had a 4.9 kernel. Is this available via a yum repo?

There is one in the CentOS xen repo. Then another one is under experimental.

[jimj]

There is one in the CentOS xen repo. Then another one is under experimental.

Thanks