Mikrotik Router Cable Setup

[Leda Billock]

TheSerial Console and Serial Terminal are tools, used to communicate with devices and other systems that are interconnected via the serial port. The serial terminal may be used to monitor and configure many devices - including modems, network devices (including MikroTik routers), and any device that can be connected to a serial (asynchronous) port.

The Serial Console feature is for configuring direct-access configuration facilities (monitor/keyboard and serial port) that are mostly used for initial or recovery configuration. A special null-modem cable is needed to connect two hosts (like two PCs, or two routers; not modems). Note that a terminal emulation program (e.g., HyperTerminal on Windows or minicom on Linux) is required to access the serial console from another computer. Default settings of the router's serial port are 115200 bits/s (for x86 default is 9600 bits/s), 8 data bits, 1 stop bit, no parity, hardware (RTS/CTS) flow control.

Serial communications between devices are done with RS232, it is one of the oldest and most widely spread communication methods in the computer world. It was used for communication with the modems or other peripheral devices DTE/DCE. In the modern world, the main use of serial communication is DTE/DTE communication (Data Terminal Equipment) e.g. using a null-modem cable. There are several types of null modem cables and some of them may not work with RouterBoards at all.

It allows data-only traffic on the cross-connected Rx/Tx lines. Hardware flow control is not possible with this type of cable. The only way to perform flow control is with software flow control using the XOFF and XON characters.

RouterOS allows to communicate with devices and other systems that are connected to the router via the serial port using a /system serial-terminal command. All keyboard input will be forwarded to the serial port and all data from the port is output to the connected device.

First, you have to have a free serial port, if the device has only one serial port (like all RouterBoards, WRAP/ALIX boards, etc.) you will have to disable the system console on this serial port to be able to use it as Serial Terminal for connection to other equipment (switches, modems, etc):

Note that there are some caveats you should be aware of! Take your time understanding those limits to avoid strange things to happen when connecting a device to a serial port on a RouterBoard:

Having text coming out of the serial port to the connected device might confuse your attached device. Furthermore, in the standard config, you can enter the RouterBOOT menu by pressing ANY key. So if your serial device sends any character to the serial port of your RouterBoard during boot time, the RouterBoard will enter the RouterBOOT menu and will NOT boot RouterOS unless you manually intervene!

Next, you will have to configure your serial port according to the serial port settings of the connected device. Using the following command you will set your serial port to 19200 Baud 8N1. What settings you need to use depends on the device you connect:

This will give you access to the device you connected to port Serial0. Ctrl-A is the prefix key, which means that you will enter a small "menu". If you need to send the Ctrl-A character to a remote device, press Ctrl-A twice.

Routers R1 and R2 are connected with serial cable and PC is connected to R1 via ethernet. Lets say we want to access router R2 via serial cable from our PC. To do this you have to set up serial interface proxy on R1. It can be done by feature called special-login.

For additional details regarding the current default configuration, please refer to the Quick Guide document provided with your device. This document outlines which ports to initially utilize for connection and instructions on device setup.

When connecting the first time to the router with the default username admin and no password (or, for some models, check user and wireless passwords on the sticker). Upon the initial boot, a notification will appear, offering you the choice to either remove the default configuration (even if the default config has only an IP address), leading to a reboot with no configuration applied, or to "Show Script" and retain the current default configuration, applying it accordingly. Since this article assumes that there is no configuration on the router, you should remove it by pressing "r" on the keyboard when prompted or click on the "Remove Configuration" button in WinBox.

Connect the ISP cable to the router's ether1 port and connect your PC to any port except ether1. Then, launch WinBox and search for your router using the neighbor discovery feature. See detailed example in Winbox article.

Dynamic address configuration is the easiest option. Simply set up a DHCP client on the public interface. The DHCP client will obtain information from your Internet Service Provider (ISP), such as an IP address, DNS servers, NTP servers, and default route, making the setup process straightforward for you.

Additionally, each service can be secured by allowed IP address or address range(the address service will reply to), although more preferred method is to block unwanted access in firewall because the firewall will not even allow to open socket

A router might have DNS cache enabled, which decreases resolving time for DNS requests from clients to remote servers. In case DNS cache is not required on your router or another router is used for such purposes, disable it.

At this point, PC is not yet able to access the Internet, because locally used addresses are not routable over the Internet. Remote hosts simply do not know how to correctly reply to your local address.

Another difference is the last rule which drops all new connection attempts from the WAN port to our LAN network (unless DstNat is used). Without this rule, if an attacker knows or guesses your local subnet, he/she can establish connections directly to local hosts and cause a security threat.

Sometimes you may want to block certain websites, for example, deny access to entertainment sites for employees, deny access to porn, and so on. This can be achieved by redirecting HTTP traffic to a proxy server and use an access-list to allow or deny certain websites.

The Serial Console and Terminal are tools, used to communicate with devices and other systems that are interconnected via serial port. The serial terminal may be used to monitor and configure many devices - including modems, network devices (including MikroTik routers), and any device that can be connected to a serial (asynchronous) port.

If you do not plan to use a serial port for accessing another device or for data connection through a modem, you can configure it as a serial console. The first serial port is configured as a serial console, but you can choose to unconfigure it to free it for other applications. A free serial port can also be used to access other routers' (or other equipment, like switches) serial consoles from a MikroTik RouterOS router. A special null-modem cable is needed to connect two hosts (like, two PCs, or two routers; not modems). Note that a terminal emulation program (e.g., HyperTerminal on Windows or minicom on linux) is required to access the serial console from another computer.

Note that the above diagram will not work if the software is configured to do hardware flow control, but the hardware does not support it (e.g., some RouterBOARD models have reduced serial port functionality). If this is the case, either turn off the hardware flow control or use a null-modem cable with loopback, which will simulate the other device's handshake signals with it's own. The diagram for such a cable is as follows:

Note that although it is recommended to have a 5-wire cable for this connection, in many cases it is enough to have 3 wires (for unlooped signals only), leaving both loops to exist only inside the connectors. Other connection schemes exist as well.

Plug one end of the serial cable into the console port (also known as a serial port or DB9 RS232C asynchronous serial port) of the RouterBOARD and the other end in your PC (which hopefully runs Windows or Linux). You can also use a USB-Serial adapter. Run a terminal program (HyperTerminal, or Putty on Windows) with the following parameters for All RouterBOARD models except 230:

All keyboard input is forwarded to the serial port and all data from the port is output to the connected device. Ctrl-A is the prefix key, which means that you will enter a small "menu" by pressing this combination of keys. The Ctrl-A character will not be sent to your device! If you need to send Ctrl-A character to remote device, press Ctrl-A twice.After exiting with Ctrl-A and then Q, the control signals of the port are lowered. The speed and other parameters of serial port may be configured in the /port directory of router console. No terminal translation on printed data is performed. It is possible to get the terminal in an unusable state by outputting sequences of inappropriate control characters or random data. Do not connect to devices at an incorrect speed and avoid dumping binary data.

The serial port to be used as a serial terminal needs to be free (e.g., there should not be any serial consoles, LCD or other configuration). Check the previous chapter to see how to disable serial console on a particular port. Use /port print command to see if some other application is still using the port.

Good afternoon.

There are several routers Mikrotik RB951UI-2HnD, flashed temporarily under the project firmware OpenWRT everything worked. I want to return the standard RouterOS firmware. I saved the keys.

I set it up according to the instructions. :Netinstall

What I tried:

Your only option is Netinstall.

I have had the same problem as you and I got it with the reset at the bottom of the router. Use a Phillips screwdriver so that the tip of the screwdriver goes slightly into the hole and makes a good connection.

Do not trust the times given by the manufacturer, in some cases I have been more than a minute, just wait for your router to be displayed in Netinstall.

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