SSH and RSYNC containerized for Synology NAS

The OpenSSH install provided with the Synology DSM is customized and often leads to many challenges when needing to rsync files over ssh to the NAS. After each upgrade you have to fight to get the setup working again.

With the introduction of Docker in DSM 5, it is easier to simply leverage a container to manage all the rsync and ssh configurations.

The image will include the following:

openssh
rsync
runit
bash
non-system user for SSH access

Configurations

SSH keypair

Example

ssh-keygen -t rsa -b 4096 -f ./sshkey

SSHD Config

Modify the example sshd_config.example file to set the USERNAME for the user allowed to ssh to the running container. Should be the same as the user account created within the image.

cp sshd_config.example sshd_config
sed -i 's/USERNAME/myuser/g' sshd_config

RSYNCD Config

Modify the example rsyncd.conf.example file to configure the paths that are being made accessible for write or read. The paths should be the same paths as specified within the docker run command below.

cp rsyncd.conf.example rsyncd.conf

Building the image

sudo docker build -t myimagename --build-arg USERNAME=myuser --build-arg PASSWORD=mypassword .

Running the image

sudo docker run -d --name mycontainername -v /a/host/path:/a/container/path -p "2222:22" myimagename

The volumes specified when running should map exactly to the entry(ies) specified within the rsyncd.conf file. The port mapping allows you to leverage another port to avoid conflicting with the SSH daemon running on the local NAS.