How to block SMTP spammers in Mikrotik

There has been a lot of problem of IP Blacklisting in an ISP Network resulting in page not opening and other problems. Out of several other cases, one of the most important cause is the use of unsecured SMTP port – TCP 25! Thus it’s a highly recommended action to block smtp spammers so safeguard your network from spammers & reduce chances of IP Blacklisting.

Mostly this activity can be done in any good quality firewall or router and we can easily block smtp spammers using some specific rule set. In this post I’m going to discuss how to block smtp spammers in Mikrotik Router OS. I’m sharing the code snippet which has been performed on the current ROS 6.38.5 and is successfully implemented & tested !

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How customers are fooled by certain Internet Service Providers regarding google latency & peering in India!

This blog post is not a just “know-how” but is to educate the Local Cable Operators (LCO’s) / Franchises who are running Broadband business as well as end users in West Bengal and other places. Guys, please just don’t listen to whatever your ISP tells / shows you. Think logically, check the possibility then only move on. Having superior google latency is no rocket science but one needs to know how it works at least!

Recently a friend of mine running an ISP in Bengal called me and explained me something really very shocking. As we all know how ISP business works in India i.e. dependent on local franchise for last mile connectivity. Now, what he said was a competitor ISP say ‘Z’ was showing his local cable operator/franchise ‘Z’ has be best possible latency towards google and its services in Bengal and no other ISP can deliver that. You may wanna know what’s the google latency? Answer is – 1 ms to,, & many other sites and that too sitting from Kolkata. Shocked?
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How to add in PRTG Mikrotik Static Queues for monitoring bandwidth utilisation

Many of us use PRTG Network Monitor for our network monitoring purpose. I personally use the free version supporting 100 sensors as it is sufficient for my network.

Now, it’s super easy to add interfaces for Bandwidth motioning via SNMP for mikrotik & other devices. We just enable SNMP on Mikrotik, add the device in PRTG & add port for SNMP Bandwidth monitoring.

But what about the static queues which we have created manually on Mikrotik? We can’t add in PRTG Mikrotik Static Queues directly like we do for all physical & logical interfaces (VLANs) present on Mikrotik. There are some small steps for doing so!
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How to run Mikrotik 64 bit RouterOS on your PC

Okay, so I’m posting this article on Mikrotik 64 bit RouterOS say after almost a year. Had been super busy with my new ventures & consulting.

We were always wondering when Mikrotik will release a x64 version for our 64 bit PCs which can support more than 2 GiG RAMs.But unfortunately mikrotik trashed the plan for Mikrotik 64 bit RouterOS & eventually released their CHR Series for Virtual Machines. While some were happy with CHR others were still looking forwards for Mikrotik 64 bit RouterOS from Mikrotik as it’s more reliable and pretty straightforward. But in reality it never happened and Mikrotik people can’t even say if it’s gonna happen or not.

So, I started some R & D’s with the ROS & stuff and came to a conclusion that yes that same x86 iso which we download from the mikrotik website is 100% compatible with 64bit version and can use >2 GiG RAM & I tested with 24 GiG.

My PC Spec’s for Mikrotik 64 bit RouterOS installation:

  • 8 Core Intel i7 4.0 GHz Processor
  • 24 GiG RAM
  • 500 GB HDD
  • 1 X 1000 mbps NIC (Just for testing)

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Download ESXi 6.0 patched with Realtek 8168, 8169 and DLink DGE-528T NIC

Relief for all those Virtualiztion Enthusiast who wants to build their Virtualization lab in their home with simple hardwares. Unfortunately, ESXi 6 donot support NICs made for consumer purpose and only supports server grade NICs. But why buy those costly NICs when all motherboards now-a-days provides us with gigabit NIC and even if you don’t have an on board gigE NIC, DLink provides a nice DGE-528T GiGE NIC for our use.

Now, for those who are new with ESXi 6 and stuffs, I have created an ISO with latest ESXi 6 which is patched with Realtek 8168, Realtek 8169 & DLink DGE-528T Drivers. Just install the ISO using your pen drive or a CD and all your supported NICs will be detected automatically.

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Installing playSMS with Gammu in Ubuntu Server 15.04 – Part 3 – Gammu installation, configuration & verification

Okay, so you have been through some comparatively easy steps but now is the ultimate step leading you to the final configuration of your server using Gammu gateway. So, have patience and configure it step by step..

For this demonstration, I will be using ZTE MF 190 dongle with a SIM Card.



Also I would like to say that since I am working in a virtualized environment there are some passthrough options required. Though I will go through those steps, you can ignore if you don’t use ESXi. Unfortunately my hardware did not support Passthrough option directly (Direct I/O) so I had to mount my USB of another PC to my server.
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Installing playSMS with Gammu in Ubuntu Server 15.04 – Part 2 – playSMS installation & configuration [with Video]

Hope you have successfully followed my first part of this tutorial series and implemented basic requirements for installing playSMS now.

Procedure for installing playSMS in Ubuntu Server 15.04:

  1. Go to Check out the latest version available, like 1.3.1 for now. Click on it. Right click on playsms-1.3.1.tar.gz –> Copy link address.
  2. Open Ubuntu shell. Download the playSMS archive using the following command:
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Installing playSMS with Gammu in Ubuntu Server 15.04 – Part 1 – Preparing the server [with Video]

Hello everyone, in this tutorial we are going to see how to set up your own SMS Gateway using playSMS & Gammu. I am writing this post after getting inspired from Mr. Syed Jahanzaib blog. Also, I must thank Mr. Anton Raharja for creating such a wonderful easy-to-use application – playSMS.

My main intention in writing this blog post is to make people aware of this useful application and help them setup their own sms gateway conveniently. I have mostly followed instructions from playSMS original documentation though there are some modifications to suit my needs. Let’s begin…

What is playSMS?

playSMS is a free, opensource web based SMS Management platform having several features like sending/receiving sms, sms poll, sms quiz and much more. [Find more about it here]

What is Gammu?

Gammu is also a free, open source command line utility, which you can use to control your phone. It can be used for SMS retrieval, backup, phonebook access and much more. It can communicate directly with mobile devices including phones and dongles. [Find more about it here]

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How to configure IOU in GNS3 for real Cisco Switching Labs

Use .ova for GNS3-IOU instead of pre configured VM.

We all may have heard the saying GNS3 is great for practicing routing labs but switching Nah Nah!! Don’t underestimate the power of GNS3. It has a special IOU feature which will let you emulate real Cisco Switch both L2 & L3 in GNS3 without any trouble.

If you want to know what is an IOU? Refer to this excellent article here else follow along…

To configure IOU in GNS3 you will need the following files:

  • GNS3 (I used v1.2.3)
  • Virtual Box
  • GNS3 IOU VM (or .ova file available on GNS3 Official Site)
  • L2 IOU image
  • L3 IOU image
  • License file

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How to give ICMP high priority in Mikrotik Router?

Hello again.. Many of my friends using mikrotik devices in their network complains that whenever users starts downloading anything ping to their gateway (Mikrotik NAS) becomes unexceptionally high and gradually results in “Request timed out”.

After inspection I found that whenever users uses 100% of their allotted bandwidth, since we have not assigned any QOS(Quality of Service) for ping (ICMP Protocol) the request drops.

For this we need to create some mangle rules for marking connection and packet for ICMP requests and ICMP reply separately and then assign a simple queue mentioning the packet mark assigning a fixed bandwidth (say 512 kbps) for it. Then we can see even if users download at full bandwidth, the ping will be <1 ms to 2 ms max.

But unfortunately, hotspot users still faces a problem as when they log in the ICMP queue is moved below and thus reduces its priority. There is also a simple solution to it as we can simply add a script in user profile which will move the ICMP queue to the top(position 0) each time an user logs in.

Thanks a lot to Mr. Syed Jahanzaib for his valuable inputs.


  1. From IP -> Firewall -> Mangle Create a rule for Chain Prerouting, protocol ICMP. (For ICMP Requests)


  2. In Action we will mark the connection and give a name – icmp-con.

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