SSH Server

RouterOS has built in SSH server that is enabled by default and is listening for incoming connections on port TCP/22. It is possible to change the port and disable the server under Services menu.

Properties

Sub-menu: /ip ssh

PropertyDescription
allow-none-crypto (yes|no; Default: no)Whether to allow connection if cryptographic algorithms are set to none.
always-allow-password-login (yes | no; Default: no)Whether to allow password login at the same time when public key authorization is configured.
forwarding-enabled (both | local | no | remote; Default: no)Allows to control which SSH forwarding method to allow:
  • no - SSH forwarding is disabled;
  • local - Allow SSH clients to originate connections from the server(router), this setting controls also dynamic forwarding;
  • remote - Allow SSH clients to listen on the server(router) and forward incoming connections;
  • both - Allow both local and remote forwarding methods.
host-key-size (1024 | 1536 | 2048 | 4096 | 8192; Default: 2048)What RSA key size to use when host key is being regenerated.
strong-crypto (yes | no; Default: no)Use stronger encryption, HMAC algorithms, use bigger DH primes and disallow weaker ones:
  • prefer 256 and 192 bit encryption instead of 128 bits;
  • disable null encryption;
  • prefer sha256 for hashing instead of sha1;
  • disable md5;
  • use 2048bit prime for Diffie Hellman exchange instead of 1024bit.

Commands

PropertyDescription
export-host-key (key-file-prefix)Export public and private RSA/DSA keys to files. Command takes one parameter:
  • key-file-prefix - used prefix for generated files, for example, prefix 'my' will generate files 'my_rsa', 'my_rsa.pub' etc.
import-host-key (private-key-file)Import and replace private DSA/RSA key from specified file. Command takes one parameter:
  • private-key-file - name of the private RSA/DSA key file
regenerate-host-key ()Generated new and replace current set of private keys (DSA, RSA) on the router. Be aware that previously imported keys might stop working.

Enabling PKI authentication

Example of importing public key for user admin

Generate SSH keys on the client device (the device you will connect from). Upload the public SSH key to the router and import it.

/user ssh-keys import public-key-file=id_rsa.pub user=admin

SSH Client

Sub-menu: /system ssh

Simple log-in to remote host

It is able to connect to remote host and initiate ssh session. IP address supports both IPv4 and IPv6.

/system ssh 192.168.88.1
/system ssh 2001:db8:add:1337::beef

In this case user name provided to remote host is one that has logged into the router. If other value is required, then user=<username> has to be used.

/system ssh 192.168.88.1 user=lala
/system ssh 2001:db8:add:1337::beef user=lala

Log-in from certain IP address of the router

For testing or security reasons it may be required to log-in to other host using certain source address of the connection. In this case src-address=<ip address> argument has to be used. Note that IP address in this case supports both, IPv4 and IPv6.

/system ssh 192.168.88.1 src-address=192.168.89.2
/system ssh 2001:db8:add:1337::beef src-address=2001:db8:bad:1000::2

in this case, ssh client will try to bind to address specified and then initiate ssh connection to remote host.

Log-in using RSA public/private key

Example of importing private key for user admin

First of all, export currently generated SSH keys to a file:

/ip ssh export-host-key key-file-prefix=admin

Two files admin_rsa and admin_rsa.pub will be generated. The pub file needs to be trusted on the SSH server side (how to enable SSH PKI on RouterOS) The private key has to be added for the particular user.

/user ssh-keys private import user=admin private-key-file=admin_rsa

Only user with full rights on the router can change 'user' attribute value under /user ssh-keys private

After the public key is installed and trusted on the SSH server, a PKI SSH session can be created.

/system ssh 192.168.1.1

Executing remote commands

To execute remote command it has to be supplied at the end of log-in line

/system ssh 192.168.88.1 "/ip address print"
/system ssh 192.168.88.1 command="/ip address print"
/system ssh 2001:db8:add:1337::beef "/ip address print"
/system ssh 2001:db8:add:1337::beef command="/ip address print"

If the server does not support pseudo-tty (ssh -T or ssh host command), like mikrotik ssh server, then it is not possible to send multiline commands via SSH

For example, sending command "/ip address \n add address=1.1.1.1/24" to MikroTik router will fail.

If you wish to execute remote commands via scripts or scheduler, use command ssh-exec.

SSH exec

Sub-menu: /system ssh-exec

Command ssh-exec is a non-interactive ssh command, thus allowing to execute commands remotely on a device via scripts and scheduler.

Retrieve information

The command will return two values:

  • exit-code: returns 0 if the command execution succeeded
  • output: returns the output of remotely executed command


Example: Code below will retrieve interface status of ether1 from device 10.10.10.1 and output the result to "Log"

:local Status ([/system ssh-exec address=10.10.10.1 user=remote command=":put ([/interface ethernet monitor [find where name=ether1] once as-value]->\"status\")" as-value]->"output")
:log info $Status

For security reasons, plain text password input is not allowed. To ensure safe execution of the command remotely, use SSH PKI authentication for users on both sides.


the user group and script policy executing the command requires test permission

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