24.5 Remote Browse Sync

Samba servers running as Local Master Browsers can be configured to synchronize with one another directly, without the need for a DMB. The notes in the smb.conf manual page explain that this is done in a Samba-specific way. The trick is fairly simple, though. Samba unicasts a MasterAnnouncement Browser Frame to the remote IP address.

You may recall that MasterAnnouncement messages are supposed to be sent to DMBs. An LMB sends them to let the DMB know that the LMB exists. The DMB then sends a NetServerEnum2 request to the LMB to collect the Browse List and merge it with the master list... but you knew that.

Samba's extension is that a Samba LMB will also respond to a MasterAnnouncement message and synchronize with the sender.

It is suggested, in the smb.conf docs, that the destination addresses be specified as subnet broadcast addresses. Current network best practices recommend against allowing directed broadcasts, however, so on most networks you won't be able to send a broadcast message to a remote subnet. To really make this feature work, you will need to know the IP address of the Local Master Browser on the remote subnet. One way to do this is to ensure that a specific Samba server on that remote LAN always wins the LMB election.

You can fiddle the PREFERRED MASTER and OS LEVEL parameters in such a way that Samba will always win the election.