Replace Dropbear to OpenSSH + SFTP

The vanilla OpenWrt out of the box has a small Dropbear SSH server. But it doesn't support the SFTP and lacks of some other features. You can install another OpenSSH server which is bigger but has more features and default on desktop systems like Ubuntu. Many routers with OpenWrt as a stock firmware use it out of the box. So for this routers you really don't need anything to do and just start using it.

• Set a Dropbear's port to some unused (e.g. 2222) and restart it

  uci set dropbear.@dropbear[0].Port=2222
  uci commit dropbear
  /etc/init.d/dropbear restart

• Ensure that the root user has a password by using the

  passwd

  command.

• Reconnect to the SSH using the new port

  ssh root@192.168.1.1 -p 2222

• Install OpenSSH server

  opkg update
  opkg install openssh-server

• Allow root access

  sed -i 's/^#PermitRootLogin prohibit-password/PermitRootLogin yes/' /etc/ssh/sshd_config

• Enable it and start

  /etc/init.d/sshd enable
  /etc/init.d/sshd start

• The OpenSSH now use the standard 22 port. Reconnect to SSH over the 22 port

  ssh root@192.168.1.1

• Now you can disable the Dropbear

  /etc/init.d/dropbear disable
  /etc/init.d/dropbear stop

• Install openssh-sftp-server package to support the SFTP protocol

  opkg update
  opkg install openssh-sftp-server

• If needed, configure the OpenSSH server in /etc/ssh/sshd_config and restart it

  /etc/init.d/sshd restart