gre tunnel basics

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  • MikroTik Site to Site GRE Tunnel Configuration with IPsec

    VPN (Virtual Private Network) is a technology that provides a secure tunnel across a public network. A private network user can send and receive data to any remote private network using VPN Tunnel as if his/her network device was directly connected to that private network. MikroTik provides GRE (Generic Routing Encapsulation) tunnel that is used to create a site to site VPN tunnel. GRE tunneling protocol which can encapsulate a wide variety of protocols creating a virtual point-to-point link was originally developed by Cisco. GRE is a stateless tunnel like EoIP and IPIP. That means if the remote end of the tunnel goes down, all traffic that was routed over the tunnels will get blackholed. To solve this problem, RouterOS have added ‘keepalive’ feature for GRE tunnels. By default keepalive is set to 10 seconds and 10 retries. GRE adds an outer header mentioning the entry point of the tunnel (SourceIP) and the exit point of the tunnel (DestinationIP) but the inner packet is kept unmodified. GRE tunnel only encapsulates IP packets but does not provide authentication and encryption. GRE tunnel with IPsec ensures IP packet encapsulation as well as authentication and encryption. IPsec usage makes your packets secure but [...]

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    Unlocking Digital Opportunities: A Beginner’s Guide to Computer Networking |   October 14, 2025

    Summary Computer networking has created the digital world, enabling communication networks that unite various regions of the world and connect any device in some way or another. Networking provides new opportunities to secure employment, act as freelance workers, or even pursue volunteer work, which is why it is worth investing in for career development. Being practical should be valued even more than theory. Even after setting up a home lab, reviewing real projects, and consulting trusted sources, you will learn [...]

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    How to Secure MikroTik RouterOS Login Users |   February 19, 2021

    MikroTik RouterOS is a bridge between WAN and LAN. So, it is mandatory to apply RouterOS login user security policy. Otherwise, RouterOS may so insecure.

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    Managing Disk Partition with the parted Tool in CentOS 7 |   March 2, 2019

    As a system administrator, sometimes you may require to manage partitions of your CentOS/Red Hat Linux Operating System. Partition management is always a risky task. But there are some useful tools those are so helpful to manage CentOS/Red Hat Linux disk partition easily. In my previous article, I discussed how to manage CentOS/Red Hat 7 HDD partitions with the fdisk utility. The fdisk tool is only eligible to manage MBR partition table. But GPT partition table is now becoming more [...]

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    MikroTik Router Static DHCP Server Configuration |   October 25, 2015

    DHCP Server assigns IP address and other related IP information (Subnet mask, Gateway and DNS) automatically to network devices. But automatic DHCP Server has some disadvantages too. If any IP device connects to any automatic DHCP network, the device will get an IP address and related IP information automatically by the DHCP Server and the device will start to use resources of this network. In this situation, the network administrator cannot know who is being connected to the network and [...]

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    CentOS 7 Network Configuration Using nmtui Tool |   August 27, 2018

    After completing CentOS 7 fresh installation, the first task to a system administrator is to configure its network so that it can communicate to other network devices. In my previous article, I discussed how to install CentOS 7.5 GUI (GNOME Desktop) step by step. If you are a new CentOS 7 user and yet you have not installed CentOS 7.5 on your server machine, feel free to study my previous article and install CentOS 7.5 GNOME Desktop according to that [...]

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    How to Separate MikroTik Hotspot and DHCP IP Pool |   October 9, 2020

    MikroTik default Hotspot Setup comes with a DHCP Server (which uses same IP Pool of Hotspot Server) to provide IP address and other network information to a connected device. Using this automatic IP address connected device can access Hotspot login page. After successfully login, a one to one NAT IP address is also assigned for the device and this process happens internally in Hotspot Server. User device cannot know this one to one NAT IP assigning. However, Hotspot Server actually [...]

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    MikroTik PCC Load Balancing over Unequal Dual WAN Links |   June 12, 2018

    Hi, you are here means you are finding a Load Balancing and Link Redundancy solution with Unequal WAN links in your MikroTik Router. If so, it is your right place. In my previous article I discussed how to configure a Dual WAN Load Balancing and Link Redundancy network using PCC method but it was assumed that both WAN links have equal bandwidth. But in real situation, you may have unequal WAN links such as ISP1 may have 10MB bandwidth and [...]

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    IP Based Virtual Hosting on CentOS 7 with Apache Server |   July 18, 2019

    Virtual Hosting is a method of hosting multiple domains on single web server. If you have multiple domains (such as domain1.com, domain2.com and so on) and want to host on single web server, Virtual Web Hosting is your right choice. Apache web server provides an easy way to manage Virtual Hosting. Virtual Hosting can be either Name Based or IP Based. In Name Based Virtual Hosting, multiple domains can be hosted on single IP address. On the other hand, in [...]

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    Restrict Internet Access Based on MAC Address in MikroTik |   February 4, 2017

    MikroTik router has a lot of features by which a network administrator can design his network as he likes. As a network administrator, sometimes you may need to allow internet access some specific devices. If other devices try to access internet, they will be rejected by your router. For example, say, you have configured a simple network like below diagram. In this network, you have configured WAN, LAN, Gateway, DNS and NAT. Also you have created queue rules for limiting [...]

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