MacOS X: Problem with accessing SMB-Shares on your Synology with "El Capitan"

Objective

I wanted to access my smb shares on my Synology from my MacBook Air that I recently updated to "El Capitan".

Motivation

As I my Synology DS209+II as my central data store where I never had problem so share files via the smb protocol with my MacBook Air as a client, I recently recognized that I can't establish a connection to the shares on my Synology after updating my MacBook Air to "El Capitan".

Prerequisites

• DS209+II
• MacBook Air (or any other Mac) with "El Capitan"

Solution

Explanation

Apparently Apple change it's security policy regarding smb-shares in "El Capitan". Those changes can lead to significant speed reduction with smb connection and even prevent you to mount a share at all. Ususally a login via the Finder menu "Go to server" is not successful whereas in the previous version of MacOS X "Mavericks" there where no problem and nothing has changed meanwhile on the server.

Solution

You can quickly fix the problem without downgrading to MacOS 10.11.4.

Open a Terminal an execute the following command:

sudo sh -c 'echo "[default]\nsigning_required=no" > /etc/nsmb.conf'

Now, restart your MacBook and you should be able to mount a shared drive from you Synology as ususal.

References:

1. http://www.heise.de/mac-and-i/meldung/OS-X-10-11-5-Abhilfe-fuer-SMB-Probleme-3222725.html (German)