“Greasy cloth” in the Internet link

A few weeks ago, I had a small project to replace one ancient Cisco router with one new MikroTik RB 2011 device. To make a long story short, I investigated the old Cisco configuration and then configured MikroTik.

After a few hours, I had the phone call. The local admin called to tell me that their Internet was terrible. There shouldn’t be any problem at all, as they are using the fiber optic link. Therefore, I connected remotely to the MikroTik device and checked its configuration.

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Removing BUSY leases from MikroTik DHCP pool

Whenever we’re designing a network, we’re trying to assign at least one continuous block of IP addresses for an automatic client assignment. Using the DHCP server, we can make network administration much easier. We can even use the DHCP server to assign an IP address for the servers in our network.

When the DHCP server spots a previously existing IP address from its DHCP leases pool, it will block that address from further assignment. This mechanism will prevent duplicated IP addresses in the same network segment.

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Dude, what happening to my Windows server?

The successful administration of every server for the great part depends on your capability to have an insight into the server’s daily operations. We may have a general picture about the status of a particular service, like an e-mail or database, and still be missing crucial signs of the improper operations on a daily level.

The simplest way to monitor any server, including Windows servers, is the SNMP monitoring of the essential parameters – CPU load, RAM usage or free disk space. Mikrotik Dude can assist us in this task.

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Connecting three sites using IPSec tunnels

So far, we have discussed how to connect the two sites through an IPSec tunnel. Most readers will be satisfied with that, as these scenarios cover most real-life situations. However, we may have a need to interconnect three or more sites using the IPSec tunnels,

Although rare, these scenarios are possible. However, we need to plan everything carefully, as we will need more IPSec policies between routers. Therefore, I will describe here how to connect the “road warrior” users with distant site.

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Custom chains in the Mikrotik Firewall

Every network packet that firewall handles can be input, output or forwarded. In relation to this, we have the three predefined chains that handle the entire network traffic. We make a list of rules that allow or block specific traffic.

Over time, our list can grow. At one point, we may have a list with several hundred rules. Mikrotik routers can have a long list, still to operate without problems. However, each netwrok packet must be respectively compared with each rule in the list until it finds appropriate.

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Mikrotik device as a L2TP/IPSec client

In the previous post we have shown a Mikrotik router as a L2TP/IPSec server. In this scenario, we are using either Windows clients or mobile devices based on Android or Apple iOS operating systems. Here is a new scenario – we may have a need to use another Mikrotik device as the VPN client.

The most common scenario is that you want to connect a remote network with a main network. Using the L2TP/IPSec VPN connection, you will have in the same time the routable tunnel and the full power of IPSec encryption.

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L2TP/IPSec for Road Warriors

In the sixth part of our Mikrotik IPSec series, we will cover the L2TP/IPSec scenario. This scenario is used to support “road warriors”, employees that need to work from home or while on the road.

This scenario is similar in some elements with the previous scenario, when one side is behind a NAT device. The main difference is that we use L2TP as the basic protocol and therefore we need to protect this VPN tunnel without encryption.

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