How to set-up a rsync server in Mac OS X / macOS

Source: https://www.jafdip.com/how-to-setup-rsyncd-on-mac-os-x/

One of the most versatile utilities developed is rsync, however; learning to effectively use the application can be a daunting task. Rsync is useful for conducting backups to remote file servers or even mirroring a local drive to a removable one. It supports transferring files over ssh as well as it’s own protocol. Unfortunately, to use the built in rsync protocol you need to set up an rsync server, which on a Mac can be quite tricky.

On the one hand, you can simply type rsync —daemon and it will start a rsync daemon running on TCP port 873. But without the appropriate rsyncd.conf things can get a little messy. In addition, if you reboot the ‘server’ the process will not restart automatically. The worst thing is to have a system that has been operational for several months suddenly stop because someone rebooted the hardware and no one remembered that the process needed to be relaunched. Personally, I think it is much better to have the system offer some more resiliency by automating this process.

On the Mac, unfortunately inetd is no longer a viable option, thus you need to use launchd and launchdctl to load your XML described process file. So, I created the following plist (property list) file that I installed as root into /Library/LaunchDaemon.

Those instructions were tested on all versions of Mac OS from 10.3 to 11.0.

1. (Optional) Install  latest rsync and ignore Mac OS X rsync
   
   brew install rsync
2. As privileged user, create a start-up configuration file
1. First step is to open the file for edit...
• If using rsync from brew:
  
  sudo vi /Library/LaunchDaemons/org.samba.rsync.plist
• If using rsync shipped with macOS
  
  sudo vi /Library/LaunchDaemons/rsync.plist
2. ...with the following contents
   
   <?xml version="1.0" encoding="UTF-8"?>
   <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
   <plist version="1.0">
   <dict>
       <key>Disabled</key>
       <false/>
       <key>Label</key>
       <string>org.samba.rsync</string>
       <key>Program</key>
       <string>/usr/local/bin/rsync</string>
       <key>ProgramArguments</key>
       <array>
           <string>/usr/local/bin/rsync</string>
           <string>--daemon</string>
           <string>--no-detach</string>
           <string>--verbose</string>
           <string>--config=/usr/local/etc/rsyncd.conf</string>
       </array>
       <key>RunAtLoad</key>
       <true/>
       <key>KeepAlive</key>
       <dict>
           <key>SuccessfulExit</key>
           <false/>
       </dict>
   </dict>
   </plist>
3. Pay special  attention to the highlighted text. 
1. Label (it appears twice): 
1. brew: org.samba.rsync
2. Mac OS: rsync
2. rsync path:
1. brew: /usr/local/bin/rsync
2. Mac OS: /usr/bin/rsync
3. Configuration file: 
1. brew: /usr/local/etc/rsyncd.conf
2. Mac OS X: /etc/rsyncd.conf
3. As privileged user, create a configuration file
1. Open file for edit...
• If using rsync from brew
  
  sudo vi /usr/local/etc/rsyncd.conf 
• If using rsync shipped with macOS
  
  sudo vi /etc/rsyncd.conf
2. with
   
   hosts allow = 192.168.0.0/16
   reverse lookup = false
   list = yes
   uid = nobody
   gid = wheel
   log file = /var/log/rsync.log
   motd file = /usr/local/etc/rsyncd.motd
   [Backup]
     path = /Volumes/BackupVolume/BACKUPS/
     comment = Backup area
     read only = false
     write only = false
     use chroot = false
   #  max verbosity = 100
   [vol014]
     path = /Volumes/vol014
     comment = Software area
     read only = false
     write only = false
     use chroot = false
   #  max verbosity = 100
   
3. Pay attention to the highlighted text
1. My rsync server is limited to my internal network
2. There is a specific log file for my rsync server
3. macOS is based on FreeBSD. The root group is wheel, not root (like Linux).
4. On connecting, the user receives a large screen message
1. brew: /usr/local/etc/rsyncd.motd
2. Mac OS X: /etc/rsyncd.motd
4. As privileged user, create a Message-Of-The-Day file (/usr/local/etc/rsyncd.motd) 
1. My name:
   https://www.patorjk.com/software/taag/#p=display&f=Big&t=ANDREAS%0ABERENDSEN%0A
2. Host name: 
   https://www.patorjk.com/software/taag/#p=display&f=Big&t=HG000005%0A
3. brew:
   
   sudo vi /usr/local/etc/rsyncd.motd
4. Mac OS X:
   
   sudo vi /etc/rsyncd.motd
5. with
   
   ==================================================================== 2020-Oct-07
              _   _ _____  _____  ______           _____
        /\   | \ | |  __ \|  __ \|  ____|   /\    / ____|
       /  \  |  \| | |  | | |__) | |__     /  \  | (___
      / /\ \ | . ` | |  | |  _  /|  __|   / /\ \  \___ \
     / ____ \| |\  | |__| | | \ \| |____ / ____ \ ____) |
    /_/__  \_\_|_\_|_____/|_|__\_\______/_/   _\_\_____/__ _   _
    |  _ \|  ____|  __ \|  ____| \ | |  __ \ / ____|  ____| \ | |
    | |_) | |__  | |__) | |__  |  \| | |  | | (___ | |__  |  \| |
    |  _ <|  __| |  _  /|  __| | . ` | |  | |\___ \|  __| | . ` |
    | |_) | |____| | \ \| |____| |\  | |__| |____) | |____| |\  |
    |____/|______|_|  \_\______|_| \_|_____/|_____/|______|_| \_|
   
   UNAUTHORIZED ACCESS TO THIS DEVICE IS PROHIBITED
   
   You must have explicit, authorized permission to access or configure this 
   device. Unauthorized attempts and actions to access or use this system may 
   result in civil and/or criminal penalties. All activities performed on this 
   device are logged and monitored.
   
   Name  : HG000007.local
   
       Model Name            : Mac mini
       Model Identifier      : Macmini7,1
       Processor Name        : Dual-Core Intel Core i5
       Processor Speed       : 1,4 GHz
       Number of Processors  : 1
       Total Number of Cores : 2
       L2 Cache (per Core)   : 256 KB
       L3 Cache              : 3 MB
       Boot ROM Version      : 249.0.0.0.0
       SMC Version (system)  : 2.24f32
       Serial Number (system): C07R11PZG1HV
       Hardware UUID         : F61F0D48-B3E7-5335-8EAB-5B93B8CF2BE0
   
   Memory: 4GB (BANK 0/DIMM0: 2GB DDR3 1600 MHz)
               (BANK 1/DIMM0: 2GB DDR3 1600 MHz)
   
   Swap  :
   Disk  :
       /dev/disk0 (internal, physical):  2.0 TB
       /dev/disk1 (synthesized)       :  2.0 TB
       /dev/disk2 (external, physical):  2.0 TB
       /dev/disk3 (external, physical):  8.0 TB
       /dev/disk4 (external, virtual) : 10.0 TB
   
   Distro: Darwin Kernel Version 19.6.0 xnu-6153.141.1~1/RELEASE_X86_64 x86_64
           ProductName:    Mac OS X
           ProductVersion: 10.15.6
           BuildVersion:   19G2021
   
   Network:
       en0: 192.168.0.2/24   38:c9:86:30:35:8c  Ethernet
       en1: 192.168.1.28/24  bc:54:36:cd:a5:c4  Wi-fi
   
     _    _  _____  ___   ___   ___   ___   ___ ______
    | |  | |/ ____|/ _ \ / _ \ / _ \ / _ \ / _ \____  |
    | |__| | |  __| | | | | | | | | | | | | | | |  / /
    |  __  | | |_ | | | | | | | | | | | | | | | | / /
    | |  | | |__| | |_| | |_| | |_| | |_| | |_| |/ /
    |_|  |_|\_____|\___/ \___/ \___/ \___/ \___//_/
   ===================================================== /usr/local/etc/rsyncd.motd
   
5. (Mac OS 10.15 & 10.14) Allow rsync to have access to the volumes. This is using the GUI. I am researching how to it form the command line.
1. For Mac OS 10.15, 10.14
1. System Preferences > Security & Privacy > Privacy > Full Disk Access
2. Click the pad lock and type the admin (your user account) password
3. Click the plus sign ("+") just below list box
4. Navigate to /usr/local/bin/ and chose rsync
6. Launch the rsync server
• If using rsync from brew 
  
  sudo launchctl load /Library/LaunchDaemons/org.samba.rsync.plist
• If using rsync shipped with macOS
  
  sudo launchctl load /Library/LaunchDaemons/rsync.plist
7. Check rsync is up and running
   

   $ rsync --stats 192.168.0.5::
   
   ==================================================================== 2021-Jan-22
   
              _   _ _____  _____  ______           _____
   
        /\   | \ | |  __ \|  __ \|  ____|   /\    / ____|
   
       /  \  |  \| | |  | | |__) | |__     /  \  | (___
   
      / /\ \ | . ` | |  | |  _  /|  __|   / /\ \  \___ \
   
     / ____ \| |\  | |__| | | \ \| |____ / ____ \ ____) |
   
    /_/__  \_\_|_\_|_____/|_|__\_\______/_/   _\_\_____/__ _   _
   
    |  _ \|  ____|  __ \|  ____| \ | |  __ \ / ____|  ____| \ | |
   
    | |_) | |__  | |__) | |__  |  \| | |  | | (___ | |__  |  \| |
   
    |  _ <|  __| |  _  /|  __| | . ` | |  | |\___ \|  __| | . ` |
   
    | |_) | |____| | \ \| |____| |\  | |__| |____) | |____| |\  |
   
    |____/|______|_|  \_\______|_| \_|_____/|_____/|______|_| \_|
   
   
   
   UNAUTHORIZED ACCESS TO THIS DEVICE IS PROHIBITED
   
   
   
   You must have explicit, authorized permission to access or configure this
   
   device. Unauthorized attempts and actions to access or use this system may
   
   result in civil and/or criminal penalties. All activities performed on this
   
   device are logged and monitored.
   
   
   
   Name  : HG000005.local
   
   
   
       Model Name            : Mac mini
   
       Model Identifier      : Macmini7,1
   
       Processor Name        : Dual-Core Intel Core i5
   
       Processor Speed       : 1,4 GHz
   
       Number of Processors  : 1
   
       Total Number of Cores : 2
   
       L2 Cache (per Core)   : 256 KB
   
       L3 Cache              : 3 MB
   
       Boot ROM Version      : 249.0.0.0.0
   
       SMC Version (system)  : 2.24f32
   
       Serial Number (system): C07R11PZG1HV
   
       Hardware UUID         : F61F0D48-B3E7-5335-8EAB-5B93B8CF2BE0
   
   
   
   Memory: 4GB (BANK 0/DIMM0: 2GB DDR3 1600 MHz)
   
               (BANK 1/DIMM0: 2GB DDR3 1600 MHz)
   
   
   
   Swap  :
   
   Disk  :
   
       /dev/disk0 (internal, physical):  2.0 TB
   
       /dev/disk1 (synthesized)       :  2.0 TB
   
       /dev/disk2 (external, physical):  2.0 TB
   
       /dev/disk3 (external, physical):  8.0 TB
   
       /dev/disk4 (external, virtual) : 10.0 TB
   
   
   
   Distro: Darwin Kernel Version 19.6.0 xnu-6153.141.1~1/RELEASE_X86_64 x86_64
   
           ProductName:    Mac OS X
   
           ProductVersion: 10.15.6
   
           BuildVersion:   19G2021
   
   
   
   Network:
   
       en0: 192.168.0.2/24   38:c9:86:30:35:8c  Ethernet
   
       en1: 192.168.1.28/24  bc:54:36:cd:a5:c4  Wi-fi
   
   
   
     _    _  _____  ___   ___   ___   ___   ___ ______
   
    | |  | |/ ____|/ _ \ / _ \ / _ \ / _ \ / _ \____  |
   
    | |__| | |  __| | | | | | | | | | | | | | | |  / /
   
    |  __  | | |_ | | | | | | | | | | | | | | | | / /
   
    | |  | | |__| | |_| | |_| | |_| | |_| | |_| |/ /
   
    |_|  |_|\_____|\___/ \___/ \___/ \___/ \___//_/
   
   ===================================================== /etc/rsyncd.motd
   
   
   
   drwxrwxrwx         748 2021/01/01 16:38:50 .
   
   -rwxrwxrwx       24580 2021/01/22 14:44:36 .DS_Store
   
   -rw-r--r--           0 2020/10/17 01:34:43 .com.apple.timemachine.donotpresent
   
   -rw-r--r--           0 2020/11/17 09:49:17 .com.apple.timemachine.supported
   
   -rw-------   181585142 2020/12/25 19:15:02 Projetos-20201225T180620Z-001.zip
   
   -rw-r--r--      178322 2020/12/17 21:54:08 apple_power_list.txt
   
   drwxrwxrwx         272 2020/10/14 21:03:18 .DocumentRevisions-V100-bad-1
   
   drwx------         272 2020/11/27 19:54:09 .Spotlight-V100
   
   drwxrwxrwt         136 2019/10/10 03:15:08 .TemporaryItems
   
   d-wx--x--t         102 2020/12/23 06:08:41 .Trashes
   
   drwx------         238 2020/11/19 18:54:35 .finf
   
   drwxrwxrwx       21114 2020/12/23 06:08:44 .fseventsd
   
   drwxrwxrwx        1394 2020/10/29 12:57:15 Disc Images
   
   drwxrwxrwx        1292 2020/11/25 18:32:44 Internet Mirrors
   
   drwxr-xr-x         136 2020/11/03 18:27:23 Library
   
   drwxr-xr-x         306 2020/11/07 14:22:10 Software Repository
   
   drwxr-xr-x         136 2019/08/15 23:47:19 torrent_NB
   
   
   
   Number of files: 17
   
   Number of files transferred: 0
   
   Total file size: 181788044 bytes
   
   Total transferred file size: 0 bytes
   
   Literal data: 0 bytes
   
   Matched data: 0 bytes
   
   File list size: 481
   
   File list generation time: 0.001 seconds
   
   File list transfer time: 0.000 seconds
   
   Total bytes sent: 75
   
   Total bytes received: 3065
   
   
   
   sent 75 bytes  received 3065 bytes  6280.00 bytes/sec
   
   total size is 181788044  speedup is 57894.28
   
       

8. Troubleshooting
1. If not working, try to run the rsync from the command line while tailing the log files:
1. In one terminal window (or tab), run
   tail -f /var/log/rsync.log
2. In another terminal window (or tab), run the following command (the --port switch is to ensure that there are no security limitations on the server):
   sudo /usr/local/bin/rsync -v -v -v -v -v --daemon --no-detach --config=/usr/local/etc/rsync.conf --port=5678
3. From another terminal window (or tab), or another computer, run
   rsync rsync://<your server-ip-or-name>:5678
2. If you receive the motd message, then the problem can be the port or the plist file