buildroot/package/dropbear/dropbear.service

[Unit]
Description=Dropbear SSH daemon
After=syslog.target network.target auditd.service

[Service]
# If /etc/dropbear is not a directory, and
#   - the filesystem is RO (i.e. we can not rm the symlink),
#     create the directory pointed to by the symlink.
#   - the filesystem is RW (i.e. we can rm the symlink),
#     replace the symlink with an actual directory
ExecStartPre=/bin/sh -c '\
if ! [ -d /etc/dropbear ]; then \
    if rm -f /etc/dropbear; then \
        mkdir -p /etc/dropbear; \
    else \
        mkdir -p $(readlink /etc/dropbear); \
    fi; \
fi'
ExecStart=/usr/sbin/dropbear -F -R
ExecReload=/bin/kill -HUP $MAINPID

[Install]
WantedBy=multi-user.target