TIL

Installing ssh-copy-id on a Synology NAS

#tools#synology

ssh-copy-id isn’t installed on DSM 7+ and is unavailable from the Synology Package Center (or the SynoCommunity Package repo).

I wanted to copy SSH keys between my DS420+ and my other servers so let’s install the tool to do that.

Terminal window
mkdir -p "$HOME/.local/bin" "$HOME/.ssh"
chmod 700 "$HOME/.ssh"


curl -fL \
  https://raw.githubusercontent.com/openssh/openssh-portable/master/contrib/ssh-copy-id \
  -o "$HOME/.local/bin/ssh-copy-id" &&
chmod 755 "$HOME/.local/bin/ssh-copy-id"

Validate the installation and add to the PATH

Terminal window
"$HOME/.local/bin/ssh-copy-id" -h


# make the command available on the PATH in the current session
export PATH="$HOME/.local/bin:$PATH"


# [optional] persist it across new sessions
echo 'export PATH="$HOME/.local/bin:$PATH"' > ~/.profile

Finally we can call it with the key we wish to copy

Terminal window
ssh-copy-id -i "$HOME/.ssh/id_ed25519.pub" username@destination

If you don’t have a key yet, generate one using ssh-keygen which is installed on DSM 7+

Terminal window
ssh-keygen -t ed25519

I also add an SSH conf entry to make it easier to connect to each server

Host desktop
    HostName <ip_address>
    User <user>
    IdentityFile /var/services/homes/<user>/.ssh/id_ed25519
    IdentitiesOnly yes

Then we can simply call ssh desktop to connect.