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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    MikroTik User Manager RADIUS Installation on RouterOS 7 |   July 5, 2022

    The User Manager is a MikroTik provided RADIUS Server packages. It can be used to manage users for small or medium level business. User Manger is not a default RouterOS packages. So, we have to install user manager as an extra package in RouterOS 7. RouterOS 7 has brought a massive change on User Manager package. The most important change is managing User Manager from Winbox while in RouterOS 6 the User Manager package can only be managed from Web [...]

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    MikroTik DHCP Server Configuration in RouterOS 7 |   October 14, 2015

    Dynamic Host Configuration Protocol (DHCP) is a client/server protocol. DHCP server automatically provides an Internet Protocol (IP) address and other related information such as subnet mask, default gateway and DNS to DHCP clients. DHCP server and client use UDP port 67 and 68 for communication. In a network, a DHCP client (IP devices such as Desktop, Laptop, Smartphone etc.) requests for an IP lease to DHCP servers and a DHCP server responses allocating IP address and other related IP information [...]

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    OpenVPN Configuration over Port 443 on Ubuntu Linux |   June 20, 2022

    OpenVPN provides a secure and encrypted VPN tunnel across public network. Unlike PPTP and L2TP VPN Services which can be blocked, OpenVPN can highly be customized and even can be run over so popular TCP Port 443. So, OpenVPN cannot easily be blocked. OpenVPN uses SSL/TLS Certificates. So, OpenVPN Tunnel is a trusted tunnel to send and receive data across public network. OpenVPN Server can easily install on Ubuntu Server. Installing OpenVPN Server on Ubuntu Server, we can connect Windows, [...]

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    MikroTik Site to Site VPN with L2TP/IPsec |   March 3, 2018

    VPN (Virtual Private Network) is a technology that provides a secure and encrypted tunnel across a public network. A private network user can send and receive data to any remote private network using this VPN Tunnel as if his/her network device was directly connected to that private network. MikroTik L2TP server is one of the most popular VPN services. It provides a secure and encrypted tunnel across public network for transporting IP traffic using PPP. L2TP/IPsec is more secure than [...]

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    FreeRADIUS User Profile Configuration for MikroTik Router |   January 10, 2019

    FreeRADIUS is a high performance RADIUS application that accepts a large number of network devices as RADIUS Client including MikroTik Router. FreeRADIUS MySQL module helps to get user authentication and authorization information from database server and to store user accounting information in database server. Configuring MySQL user group and profile properly, freeRADIUS user restriction can easily be maintained. How to configure user group to apply user limitation was discussed in my previous article. In this article, I will discuss how [...]

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    MikroTik Configuration with PPPoE WAN Connection |   July 18, 2018

    MikroTik Router is a popular routing device to any network administrator because of having a lot of network features availability. MikroTik PPPoE Client is a special feature that is used to connect any PPPoE Server. If your ISP provides PPPoE connection, MikroTik Router is able to connect that PPPoE Server using PPPoE Client. In my previous article, I discussed how to configure MikroTik Router with static WAN connection and in this article I will show how to configure MikroTik Router [...]

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    CentOS 7.5 Installation Step by Step with GUI (GNOME Desktop) |   August 15, 2018

    Linux is a free and open source operating system developed by Linus Torvalds on September 17, 1991. It is mainly used as server environment. A lot of Linux distributions are present today. Among them, Red Hat Linux is used as enterprise Linux. Red Hat is also known as Red Hat commercial Linux that means Red Hat is a paid service program. CentOS (Community Enterprise Operating System) is another Linux distribution that provides a free and open source, enterprise-class, community-supported server platform functionally compatible with [...]

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    How to Properly Downgrade MikroTik RouterOS and Firmware |   October 2, 2019

    MikroTik RouterOS is in constant development and new features or bug fixes are frequently available, sometimes even monthly. So, it is always recommend upgrading MikroTik RouterOS to a latest and stable version before beginning any configuration. But sometimes you may face that the upgraded version is not working properly according to your demand or you may upgrade to a new version that you don’t want. In this case, you should come back to your workable RouterOS version and firmware. Upgrading RouterOS [...]

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