Layer 7 Firewall on Mikrotik
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The document provides an overview of a webinar conducted by GLC Networks on Layer 7 firewalls using MikroTik, emphasizing prerequisites such as knowledge of networking layers and firewall functionalities. It covers topics including regular expressions, firewall rule creation, practical tips, and the differences in traffic handling across various layers. The session aims to educate participants on managing network access effectively while sharing best practices and fostering community engagement.
![www.glcnetworks.com
Regular Expression (REGEX), part 1
● Regex = Regular Expression, a feature to search pattern in a data (useful to
apply custom filter)
● Applied on filter (l7 firewall, routing filter)
● Regex code:
○ () → grouping characters together
○ . → match 1 character
○ ?, *, + → shows how the previous character is repeated
■ ? → match 0 or 1 repetition of previous string
■ * → match 0 or many repetition of previous string
■ + → match 1 or many repetition of previous string
○ ^ → matches the beginning of string
○ $ → matches at the end of string
○ → escape character (ffrfom ?*+|^$)
○ [] → match 1 character from the bracket
■ [abc] → match 1 character from the bracket (a or b or c)
■ [a-z] → match 1 character from the bracket (a to z)
●
19](https://image.slidesharecdn.com/20210527layer7firewallonmikrotik-210528035058/85/Layer-7-Firewall-on-Mikrotik-19-320.jpg)
![www.glcnetworks.com
Regular Expression (REGEX), part 2
● Regex code:
○ | → similar to or, match left or right part
○ [x09-x0d -~] → match on all printable ASCII characters & space
○ [x09-x0d ] → match a TAB, LF, Vertical Tab, Form Feed, Carriage Return (CR) or space
○ [!-~] → match non-whitespace printable characters
○
20](https://image.slidesharecdn.com/20210527layer7firewallonmikrotik-210528035058/85/Layer-7-Firewall-on-Mikrotik-20-320.jpg)
Layer 7 Firewall on Mikrotik
- 1. www.glcnetworks.com Layer 7 Firewall on mikrotik GLC Webinar, 27 May 2021 Achmad Mardiansyah achmad@glcnetworks.com GLC Networks, Indonesia 1 L7 firewall
- 2. www.glcnetworks.com Agenda ● Introduction ● Review prerequisite knowledge ● Firewall ● L7 firewall ● Tips and trick ● Live practice ● Q & A 2
- 4. www.glcnetworks.com What is GLC? ● Garda Lintas Cakrawala (www.glcnetworks.com) ● Based in Bandung, Indonesia ● Areas: Training, IT Consulting ● Certified partner for: Mikrotik, Ubiquity, Linux foundation ● Product: GLC radius manager ● Regular event 4
- 5. www.glcnetworks.com Trainer Introduction ● Name: Achmad Mardiansyah ● Base: bandung, Indonesia ● Linux user since 1999, mikrotik user since 2007, UBNT 2011 ● Mikrotik Certified Trainer (MTCNA/RE/WE/UME/INE/TCE/IPv6) ● Mikrotik/Linux Certified Consultant ● Website contributor: achmadjournal.com, mikrotik.tips, asysadmin.tips ● More info: http://au.linkedin.com/in/achmadmardiansyah 5
- 6. www.glcnetworks.com Past experience 6 ● 2021 (Congo DRC, Malaysia): network support, radius/billing integration ● 2020 (Congo DRC, Malaysia): IOT integration, network automation ● 2019, Congo (DRC): build a wireless ISP from ground-up ● 2018, Malaysia: network revamp, develop billing solution and integration, setup dynamic routing ● 2017, Libya (north africa): remote wireless migration for a new Wireless ISP ● 2016, United Kingdom: workshop for wireless ISP, migrating a bridged to routed network
- 7. www.glcnetworks.com About GLC webinar? ● First webinar: january 1, 2010 (title: tahun baru bersama solaris - new year with solaris OS) ● As a sharing event with various topics: linux, networking, wireless, database, programming, etc ● Regular schedule ● Irregular schedule: as needed ● Checking schedule: http://www.glcnetworks.com/schedule ● You are invited to be a presenter ○ No need to be an expert ○ This is a forum for sharing: knowledge, experiences, information 7
- 8. www.glcnetworks.com Please introduce yourself ● Your name ● Your company/university? ● Your networking experience? ● Your mikrotik experience? ● Your expectation from this course? 8
- 9. www.glcnetworks.com Prerequisite ● This presentation some prerequisite knowledge ● We assume you already know: ○ 7 OSI layer ○ Encapsulation ○ How to use mikrotik device ○ Mikrotik firewall ○ Regular expression ○ 9
- 11. www.glcnetworks.com 7 OSI layer & protocol 11 ● OSI layer Is a conceptual model from ISO (International Standard Organization) for project OSI (Open System Interconnection) ● When you send a message with a courier, you need to add more info to get your message arrived at the destination (This process is called encapsulation) ● What is protocol ○ Is a set of rules for communication ○ Available on each layer ● Communication consist of series encapsulation ○ SDU: service data unit (before PDU) ○ PDU: protocol data unit (after header is added)
- 12. www.glcnetworks.com Layered model (TCP/IP vs ISO) and encapsulation 12 / datagram
- 13. www.glcnetworks.com Layer 4 header (which one is TCP?) 13
- 14. www.glcnetworks.com Layer 3 header (which one is IPv4?) 14
- 15. www.glcnetworks.com Ethernet header (which is the MTU?) 15
- 17. www.glcnetworks.com Did you notice? ● There is a big overhead on encapsulation process ● More encapsulation means less payload? 17
- 18. www.glcnetworks.com HUB, switch, router, firewall 18
- 19. www.glcnetworks.com Regular Expression (REGEX), part 1 ● Regex = Regular Expression, a feature to search pattern in a data (useful to apply custom filter) ● Applied on filter (l7 firewall, routing filter) ● Regex code: ○ () → grouping characters together ○ . → match 1 character ○ ?, *, + → shows how the previous character is repeated ■ ? → match 0 or 1 repetition of previous string ■ * → match 0 or many repetition of previous string ■ + → match 1 or many repetition of previous string ○ ^ → matches the beginning of string ○ $ → matches at the end of string ○ → escape character (ffrfom ?*+|^$) ○ [] → match 1 character from the bracket ■ [abc] → match 1 character from the bracket (a or b or c) ■ [a-z] → match 1 character from the bracket (a to z) ● 19
- 20. www.glcnetworks.com Regular Expression (REGEX), part 2 ● Regex code: ○ | → similar to or, match left or right part ○ [x09-x0d -~] → match on all printable ASCII characters & space ○ [x09-x0d ] → match a TAB, LF, Vertical Tab, Form Feed, Carriage Return (CR) or space ○ [!-~] → match non-whitespace printable characters ○ 20
- 22. www.glcnetworks.com On which layer does the (traditional) Firewall works? 22 ● All firewall inspect traffic between segment → layer 3 ● Some firewall supports tracking → layer 4 ● Some firewall support inside-segment filtering → layer 2 ● See the encapsulation process before
- 23. www.glcnetworks.com What is Mikrotik firewall? ● Is a feature to ○ Control network access (filter) ○ Modify network header (NAT) ○ Marking packet for further processing (mangle) ● Developed from linux ● Consist of 2 parts: matcher & action ● Executed sequentially ● Netadmin must understand the application’s characteristics in order to build a matcher (e.g. browsing → using TCP/UDP port 80,443) 23
- 24. www.glcnetworks.com How firewall works? ● Setup matcher -> then action ● Mikrotik has lots of options for matcher -> very flexible ● Matcher + Action = Firewall rule ● Rule is executed sequentially 24
- 25. www.glcnetworks.com 25 Where the packet is processed? A: see packet flow Note: ipsec is removed in this diagram
- 26. www.glcnetworks.com 26 26 What's the difference between forward and input? FORWARD INPUT
- 28. www.glcnetworks.com What is Layer-7 Firewall on mikrotik? ● layer7-protocol is a method of searching for patterns in ICMP/TCP/UDP payload streams ● Is used as matchers ● L7 matcher collects the first 10 packets of a connection or the first 2KB, stored them in a buffer, and then search for pattern. ● IF pattern not found → pass ● Doesnt guarantee always work → application has its own pattern 28
- 29. www.glcnetworks.com p2p matcher is not available anymore ● P2p matchers is not available since 6.39 ● Previously p2p matchers is based on pattern matchers ● Because torrent traffic now is encrypted, the pattern matching is useless ● Mikrotik remove the p2p matchers feature ● Need a different approach to deal with torrent traffic 29 Not available anymore
- 31. www.glcnetworks.com Example: Create firewall rule 31
- 32. www.glcnetworks.com Not recommended!! ● Its not recommended to put direct action on packet (drop/reject). 32
- 34. www.glcnetworks.com Tips and trick ● Applied on forward chain → l7 firewall must see both directions (inbound and outbound) ● Combine it with address-list/connection-mark. After match is done, then put it on address-list. → to reduce CPU usage ● Put the l7 rules on top → to reduce cpu usage ● Do not check packet that previously marked. Use “connection-mark=no-mark” or “packet-mark=no-mark” → to reduce CPU ● Do not check packet that previously put on address-list. ● L7 firewall cannot inspect HTTPS payload ● If you want to match based on https header and domain name, use “tls-host” ● Do not use l7 on high traffic ● Be careful when blocking based on IP address, it can host multiple domain. ○ If you block youtube IP address, those IP addresses are used for google drive and other services 34
- 35. www.glcnetworks.com Tips and trick ● L7 protocol references: ○ http://www.mikrotik.com/download/share/l7_protocols_may_2009.zip ○ https://wiki.mikrotik.com/wiki/Manual:IP/Firewall/L7 ○ http://l7-filter.sourceforge.net/ ● Some regex references ○ https://regexone.com/ ○ http://regexr.com/ ○ https://regex101.com/ ○ http://buildregex.com/ ● 35
- 37. www.glcnetworks.com preparation ● SSH client ● SSH parameters ○ SSH address ○ SSH port ○ SSH username ○ SSH password 37
- 39. www.glcnetworks.com Interested? Just come to our training... ● Topics are arranged in systematic and logical way ● You will learn from experienced teacher ● Not only learn the materials, but also sharing experiences, best-practices, and networking 39
- 40. www.glcnetworks.com End of slides ● Thank you for your attention ● Please submit your feedback: http://bit.ly/glcfeedback ● Find our further event on our website : https://www.glcnetworks.com/en/ ● Like our facebook page: https://www.facebook.com/glcnetworks ● Slide: https://www.slideshare.net/glcnetworks/ ● Recording (youtube): https://www.youtube.com/c/GLCNetworks ● Stay tune with our schedule ● Any questions? 40