Turn off packet signing for SMB 2 and SMB 3 connections

on

https://support.apple.com/en-gb/HT205926

Original Post on Apple support.
Turn off packet signing for SMB 2 and SMB 3 connections.

Learn how to turn off packet signing on your Mac.

In macOS 10.13.4 and later, packet signing is off by default. Packet signing for SMB 2 or SMB 3 connections turns on automatically when needed if the server offers it. The instructions in this article apply to macOS 10.13.3 and earlier.

When you use an SMB 2 or SMB 3 connection, packet signing is turned on by default. You might want to turn off packet signing if:

  • Performance decreases when you connect to a third-party server.
  • You can’t connect to a server that doesn’t support packet signing.
  • You can’t connect a third-party device to your macOS SMB server.

If you turn off packet signing, you lower the security of the SMB connection. Turn off packet signing only if both the client and server are on a secure network.

Turn off packet signing on a macOS client

Check to see if your macOS computer has an /etc/nsmb.conf file.

If your macOS computer has a /etc/nsmb.conf file

  1. Open the /etc/nsmb.conf file.
  2. Set the signing_required value to “no,” like this:
    [default]
    signing_required=no

  3. Save the /etc/nsmb.conf file.
  4. Disconnect and then reconnect any mounted SMB shares to make the changes take effect.

If your macOS computer doesn’t have an /etc/nsmb.conf file

  1. Open Terminal.
  2. Use these commands to create an /etc/nsmb.conf file that has a signing_required value that’s set to “no”:
    sudo -s
    echo "[default]" >> /etc/nsmb.conf
    echo "signing_required=no" >> /etc/nsmb.conf
    exit

  3. Disconnect and then reconnect any mounted SMB shares to make the changes take effect.

Turn off packet signing on a macOS computer that hosts SMB shares

Follow the steps on macOS or on macOS Server.

On macOS

  1. Choose Apple menu > System Preferences, then click Sharing.
  2. Clear the File Sharing checkbox, then close the Sharing pane.
  3. In Terminal, use this command:
    sudo defaults write /Library/Preferences/SystemConfiguration/com.apple.smb.server SigningRequired -bool FALSE
  4. Choose Apple menu > System Preferences, then click Sharing.
  5. Select the File Sharing checkbox, then close the Sharing pane.

On macOS Server

  1. Open Terminal.
  2. In Terminal, use these commands to make packet signing optional for clients:
    sudo defaults write /Library/Preferences/SystemConfiguration/com.apple.smb.server SigningRequired -bool FALSE

    sudo /usr/libexec/smb-sync-preferences

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