Building a Netfilter Firewall Module SINGING LESSON We’Ll Show You How to Build Your Own Netfil- Ter Extension with This Example of a Musical
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SNMP Trap - Firewall Rules
SNMP Trap - Firewall Rules Article Number: 87 | Rating: 1/5 from 1 votes | Last Updated: Wed, Jan 13, 2021 at 4:42 PM Fir e wall Rule s These steps explain how to check if the Operating System (OS) of the Nagios server has firewall rules enabled to allow inbound SNMP Trap UDP port 162 traffic. The different supported OS's have different firewall commands which are explained as follows. You will need to establish an SSH session to the Nagios server that is receiving SNMP Traps. RHEL 7/8 | C e nt O S 7/8 | O r ac le Linux 7/8 First check the status of the firewall: systemctl status firewalld.service IF the firewall is running , it should product output like: ● firewalld.service - firewalld - dynamic firewall daemon Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled) Active: active (running) since Tue 2018-11-20 10:05:15 AEDT; 1 weeks 0 days ago Docs: man:firewalld(1) Main PID: 647 (firewalld) CGroup: /system.slice/firewalld.service └─647 /usr/bin/python -Es /usr/sbin/firewalld --nofork --nopid IF the firewall is NO T running, it will produce this output: ● firewalld.service - firewalld - dynamic firewall daemon Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled) Active: inactive (dead) since Tue 2018-11-27 14:11:34 AEDT; 965ms ago Docs: man:firewalld(1) Main PID: 647 (code=exited, status=0/SUCCESS) If the firewall is NOT running, this means that inbound traffic is allowed. To ENABLE the firewall on b o o t and to s ta rt it, execute the following commands: systemctl -
Active-Active Firewall Cluster Support in Openbsd
Active-Active Firewall Cluster Support in OpenBSD David Gwynne School of Information Technology and Electrical Engineering, University of Queensland Submitted for the degree of Bachelor of Information Technology COMP4000 Special Topics Industry Project February 2009 to leese, who puts up with this stuff ii Acknowledgements I would like to thank Peter Sutton for allowing me the opportunity to do this work as part of my studies at the University of Queensland. A huge thanks must go to Ryan McBride for answering all my questions about pf and pfsync in general, and for the many hours working with me on this problem and helping me test and debug the code. Thanks also go to Theo de Raadt, Claudio Jeker, Henning Brauer, and everyone else at the OpenBSD network hackathons who helped me through this. iii Abstract The OpenBSD UNIX-like operating system has developed several technologies that make it useful in the role of an IP router and packet filtering firewall. These technologies include support for several standard routing protocols such as BGP and OSPF, a high performance stateful IP packet filter called pf, shared IP address and fail-over support with CARP (Common Address Redundancy Protocol), and a protocol called pfsync for synchronisation of the firewalls state with firewalls over a network link. These technologies together allow the deployment of two or more computers to provide redundant and highly available routers on a network. However, when performing stateful filtering of the TCP protocol with pf, the routers must be configured in an active-passive configuration due to the current semantics of pfsync. -
Campus Networking Best Practices Session 5: Wireless
Campus Networking Best Practices Session 5: Wireless LAN Hervey Allen Dale Smith NSRC & University of Oregon University of Oregon & NSRC [email protected] [email protected] Wireless LAN • Provide wireless network across your campus that has the following characteristics: – Authentication – only allow your users – Roaming – allow users to start up in one section of your network, then move to another location – Runs on your campus network Firewall/ Border Traffic Shaper Router Wireless REN switch Authentication Core Gateway Router Core Servers Network Access Control (NAC) Enterprise Identity Management • Processes and Documentation of users. – Now you must deal with this. – What to use as the back-end user store? • LDAP • Active Directory • Kerberos • Other? – Will this play nice with future use? • email, student/staff information, resource access, ... Identity Management Cont. • An example of such a project can be seen here: – http://ccadmin.uoregon.edu/idm/ • This is a retrofit on to an already retrofitted system. • Learn from others and try to avoid this situation if possible. A Wireless Captive Portal The Wireless Captive Portal • Previous example was very simple. • A Captive Portal is your chance to: – Explain your Acceptable Use Policies – Decide if you must authenticate, or – Allow users on your network and monitor for problems instead (alternate solution). – Anything else? Branding? What's Happening? • remember our initial network diagrams...? • Do you think our hotel built their own solution? • Probably not... Commercial Solutions • Aruba http://www.arubanetworks.com/ • Bradford Networks – http://www.bradfordnetworks.com/ • Cisco NAC Appliance (Clean Access) – http://www.cisco.com/en/US/products/ps6128/ • Cisco Wireless LAN Controllers – http://www.cisco.com/en/US/products/hw/wireless/ • Enterasys http://www.enterasys.com/ • Vernier http://www.verniernetworks.com Open Source Solutions • CoovaChilli (morphed from Chillispot) – http://coova.org/wiki/index.php/CoovaChilli – Uses RADIUS for access and accounting. -
Iptables with Shorewall!
Iptables with shorewall! Table of Contents 1. Install swarmlab-sec (Home PC) . 1 2. shorewall . 1 2.1. Installation . 2 3. Basic Two-Interface Firewall. 2 4. Shorewall Concepts . 3 4.1. zones — Shorewall zone declaration file . 3 4.2. interfaces — Shorewall interfaces file. 4 4.3. policy — Shorewall policy file . 4 4.4. rules — Shorewall rules file . 4 4.5. Compile then Execute . 4 5. Three-Interface Firewall. 5 5.1. zones . 6 5.2. interfaces . 6 5.3. policy . 7 5.4. rules . 7 5.5. masq - Shorewall Masquerade/SNAT definition file . 7 5.6. snat — Shorewall SNAT/Masquerade definition file . 8 5.7. Compile and Execute . 8 1. Install swarmlab-sec (Home PC) HowTo: See http://docs.swarmlab.io/lab/sec/sec.adoc.html NOTE Assuming you’re already logged in 2. shorewall Shorewall is an open source firewall tool for Linux that builds upon the Netfilter (iptables/ipchains) system built into the Linux kernel, making it easier to manage more complex configuration schemes by providing a higher level of abstraction for describing rules using text files. More: wikipedia 1 NOTE Our docker instances have only one nic to add more nic’s: create netowrk frist docker network create --driver=bridge --subnet=192.168.0.0/16 net1 docker network create --driver=bridge --subnet=192.168.0.0/16 net2 docker network create --driver=bridge --subnet=192.168.0.0/16 net3 then connect network to container connect network created to container docker network connect net1 master docker network connect net1 worker1 docker network connect net2 master docker network connect net2 worker2 now let’s look at the following image 2.1. -
Netfilter's Connection Tracking System
FILTERING POLICIES BASED UNIQUELY on packet header information are obsolete. PABLO NEIRA AYUSO These days, stateful firewalls provide advanced mechanisms to let sysadmins Netfilter’s and security experts define more intelli- gent policies. This article describes the connection implementation details of the connection tracking system tracking system provided by the Netfilter project and also presents the required Pablo Neira Ayuso has an M.S. in computer science background to understand it, such as an and has worked for several companies in the IT secu- rity industry, with a focus on open source solutions. understanding of the Netfilter framework. Nowadays he is a full-time teacher and researcher at the University of Seville. This article will be the perfect complement to understanding the subsystem that [email protected] enables the stateful firewall available in any recent Linux kernel. The Netfilter Framework The Netfilter project was founded by Paul “Rusty” Russell during the 2.3.x development series. At that time the existing firewalling tool for Linux had serious drawbacks that required a full rewrite. Rusty decided to start from scratch and create the Netfilter framework, which comprises a set of hooks over the Linux network protocol stack. With the hooks, you can register kernel modules that do some kind of network packet handling at different stages. Iptables, the popular firewalling tool for Linux, is commonly confused with the Netfilter framework itself. This is because iptables chains and hooks have the same names. But iptables is just a brick on top of the Netfilter framework. Fortunately, Rusty spent considerable time writ- ing documentation [1] that comes in handy for anyone willing to understand the framework, al- though at some point you will surely feel the need to get your hands dirty and look at the code to go further. -
Communicating Between the Kernel and User-Space in Linux Using Netlink Sockets
SOFTWARE—PRACTICE AND EXPERIENCE Softw. Pract. Exper. 2010; 00:1–7 Prepared using speauth.cls [Version: 2002/09/23 v2.2] Communicating between the kernel and user-space in Linux using Netlink sockets Pablo Neira Ayuso∗,∗1, Rafael M. Gasca1 and Laurent Lefevre2 1 QUIVIR Research Group, Departament of Computer Languages and Systems, University of Seville, Spain. 2 RESO/LIP team, INRIA, University of Lyon, France. SUMMARY When developing Linux kernel features, it is a good practise to expose the necessary details to user-space to enable extensibility. This allows the development of new features and sophisticated configurations from user-space. Commonly, software developers have to face the task of looking for a good way to communicate between kernel and user-space in Linux. This tutorial introduces you to Netlink sockets, a flexible and extensible messaging system that provides communication between kernel and user-space. In this tutorial, we provide fundamental guidelines for practitioners who wish to develop Netlink-based interfaces. key words: kernel interfaces, netlink, linux 1. INTRODUCTION Portable open-source operating systems like Linux [1] provide a good environment to develop applications for the real-world since they can be used in very different platforms: from very small embedded devices, like smartphones and PDAs, to standalone computers and large scale clusters. Moreover, the availability of the source code also allows its study and modification, this renders Linux useful for both the industry and the academia. The core of Linux, like many modern operating systems, follows a monolithic † design for performance reasons. The main bricks that compose the operating system are implemented ∗Correspondence to: Pablo Neira Ayuso, ETS Ingenieria Informatica, Department of Computer Languages and Systems. -
Hotmobile 2006
After lunch (at a pub), John- Dan Langille ended the confer- find that the paper summaries Mark Garner ([email protected]) ence by giving away books and contained in this overview are gave a presentation about writ- T-shirts. Some books were given extremely brief and are intended ing device drivers in FreeBSD. Of to people chosen randomly [by only to help you identify those course, you can’t learn how to using random() to assign num- papers you would like to read in write device drivers in an hour, bers to all attendees, then sort- full. Those readers interested in a but Garner did a good job of pro- ing] and for various feats. Some- longer summary should refer to viding an overview of the frame- one won a book by spending the Digest of Proceedings that work available. I finally learned over six hours trying to get appears at the end of the work- what has happened to minor de- through Canadian customs. shop proceedings. This digest in- vices (made unnecessary because (There was actually someone cludes a summary of the discus- of devfs). Garner also talked who had spent longer, but he sions that followed each of the about softc, a newer, more effi- had already won a book.) presentations. cient framework for writing de- This overview is based on the vice drivers, about how re- HotMobile 2006: 7th IEEE written notes taken by two stu- sources (memory, IRQs, and Workshop on Mobile Comput- dent volunteers, Tapan Parikh ports) should be handled, and ing Systems and Applications and Alex Varshavsky. -
Status of Open Source and Commercial Ipv6 Firewall Implementations (Paper)
Status of Open Source and commercial IPv6 firewall implementations Dr. Peter Bieringer AERAsec Network Services & Security GmbH [email protected] http://www.aerasec.de/ European Conference on Applied IPv6 (ECAI6) Cologne, Germany September 6 - 7, 2007 Abstract IPv6, the successor of IPv4, has been ready for production for quite some time. For security reason, firewalling in IPv6 is also an important requirement. This paper presents an overview of the status of Open Source and commer- cial implementations. Introduction With IPv4 nowadays, many client-to-server and most client-to-client communications are intercepted by gate- ways with address and port masquerading abilities, usually named Network (and Port) Address Translation (NAT, NAPT). This prohibits native client-to-client communication, if both peers are located behind such gate- ways. In this case, only special tunnelling techniques, like STUN (Simple traversal of UDP over NATs), which requires special servers located at the Internet, or other ªfirewall-piercingº methods can help to establish native and bidirectional client-to-client communication. One of the goals of IPv6 is the re-introduction of bidirectional, native end-to-end communication without play- ing any tricks on gateways in between. Also, IPv6 has a large enough address space which should suffice for the next decades. Therefore NAT was left out by design, too. Jumping back to IPv4, the initial intention of introducing NAT was the lack of IPv4 addresses for use in internal networks, while still allowing clients to open connections to the Internet via a hiding mechanism. It turned out to also protect internal networks against threats from the Internet, because under normal circumstances (bug- free stateful hiding-NAT implementation on the gateway) it©s not possible for an outside node to connect to an internal host without any dedicated rule on the gateway. -
David Gwynne <[email protected]>
firewalling with OpenBSD's pf and pfsync David Gwynne <[email protected]> Thursday, 17 January 13 introduction ‣ who am i? ‣ what is openbsd? ‣ what are pf and pfsync? ‣ how do i use them? ‣ ask questions whenever you want Thursday, 17 January 13 who am i? ‣ infrastructure architect in EAIT at UQ ‣ i do stuff, including run the firewalls ‣ a core developer in openbsd ‣ i generally play with storage ‣ but i play with the network stack sometimes Thursday, 17 January 13 what is openbsd? ‣ open source general purpose unix-like operating system ‣ descended from the original UNIX by way of berkeley and netbsd ‣ aims for “portability, standardization, correctness, proactive security and integrated cryptography.” ‣ supports various architectures/platforms Thursday, 17 January 13 what is openbsd? ‣ one source tree for everything ‣ kernel, userland, doco ‣ bsd/isc/mit style licenses on all code (with some historical exceptions) ‣ 6 month dev cycle resulting in a release ‣ 3rd party software via a ports tree ‣ emergent focus on network services Thursday, 17 January 13 what is openbsd? ‣ it is very aggressive ‣ changes up and down the stack (compiler to kernel) to make a harsher, stricter, and less predictable runtime environment ‣ minimal or no backward compatibility as things move forward ‣ whole tree is checked for new bugs ‣ randomise as much as possible all over Thursday, 17 January 13 what is openbsd? ‣ it is extremely conservative ‣ tree must compile and work at all times ‣ big changes go in at the start of the cycle ‣ we’re not afraid to back stuff out ‣ peer review is necessary ‣ we do back away from some tweaks for the sake of usability Thursday, 17 January 13 what is pf? ‣ short for packet filter ‣ the successor to IP Filter (ipf) ‣ ipf was removed due to license issues ‣ the exec summary is that it is a stateful filter for IP (v4 and v6) traffic ‣ does a little bit more than that though.. -
Sentry Firewall CD HOWTO Sentry Firewall CD HOWTO Table of Contents
Sentry Firewall CD HOWTO Sentry Firewall CD HOWTO Table of Contents Sentry Firewall CD HOWTO............................................................................................................................1 Stephen A. Zarkos, Obsid@Sentry.net....................................................................................................1 1. Introduction..........................................................................................................................................1 2. How the CD Works (Overview)..........................................................................................................1 3. Obtaining the CDROM........................................................................................................................1 4. Using the Sentry Firewall CDROM.....................................................................................................1 5. Overview of Available Configuration Directives................................................................................1 6. Setting Up a Firewall...........................................................................................................................2 7. Troubleshooting...................................................................................................................................2 8. Building a Custom Sentry CD.............................................................................................................2 9. More About the Sentry Firewall Project..............................................................................................2 -
Freebsd Handbook
FreeBSD Handbook http://www.freebsd.org/doc/en_US.ISO8859-1/books/han... FreeBSD Handbook The FreeBSD Documentation Project Copyright © 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 The FreeBSD Documentation Project Welcome to FreeBSD! This handbook covers the installation and day to day use of FreeBSD 8.3-RELEASE and FreeBSD 9.1-RELEASE. This manual is a work in progress and is the work of many individuals. As such, some sections may become dated and require updating. If you are interested in helping out with this project, send email to the FreeBSD documentation project mailing list. The latest version of this document is always available from the FreeBSD web site (previous versions of this handbook can be obtained from http://docs.FreeBSD.org/doc/). It may also be downloaded in a variety of formats and compression options from the FreeBSD FTP server or one of the numerous mirror sites. If you would prefer to have a hard copy of the handbook, you can purchase one at the FreeBSD Mall. You may also want to search the handbook. REDISTRIBUTION AND USE IN SOURCE (XML DOCBOOK) AND 'COMPILED' FORMS (XML, HTML, PDF, POSTSCRIPT, RTF AND SO FORTH) WITH OR WITHOUT MODIFICATION, ARE PERMITTED PROVIDED THAT THE FOLLOWING CONDITIONS ARE MET: 1. REDISTRIBUTIONS OF SOURCE CODE (XML DOCBOOK) MUST RETAIN THE ABOVE COPYRIGHT NOTICE, THIS LIST OF CONDITIONS AND THE FOLLOWING DISCLAIMER AS THE FIRST LINES OF THIS FILE UNMODIFIED. 2. REDISTRIBUTIONS IN COMPILED FORM (TRANSFORMED TO OTHER DTDS, CONVERTED TO PDF, POSTSCRIPT, RTF AND OTHER FORMATS) MUST REPRODUCE THE ABOVE COPYRIGHT NOTICE, THIS LIST OF CONDITIONS AND THE FOLLOWING DISCLAIMER IN THE DOCUMENTATION AND/OR OTHER MATERIALS PROVIDED WITH THE DISTRIBUTION. -
Linux Networking Cookbook.Pdf
Linux Networking Cookbook ™ Carla Schroder Beijing • Cambridge • Farnham • Köln • Paris • Sebastopol • Taipei • Tokyo Linux Networking Cookbook™ by Carla Schroder Copyright © 2008 O’Reilly Media, Inc. All rights reserved. Printed in the United States of America. Published by O’Reilly Media, Inc., 1005 Gravenstein Highway North, Sebastopol, CA 95472. O’Reilly books may be purchased for educational, business, or sales promotional use. Online editions are also available for most titles (safari.oreilly.com). For more information, contact our corporate/institutional sales department: (800) 998-9938 or [email protected]. Editor: Mike Loukides Indexer: John Bickelhaupt Production Editor: Sumita Mukherji Cover Designer: Karen Montgomery Copyeditor: Derek Di Matteo Interior Designer: David Futato Proofreader: Sumita Mukherji Illustrator: Jessamyn Read Printing History: November 2007: First Edition. Nutshell Handbook, the Nutshell Handbook logo, and the O’Reilly logo are registered trademarks of O’Reilly Media, Inc. The Cookbook series designations, Linux Networking Cookbook, the image of a female blacksmith, and related trade dress are trademarks of O’Reilly Media, Inc. Java™ is a trademark of Sun Microsystems, Inc. .NET is a registered trademark of Microsoft Corporation. Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Where those designations appear in this book, and O’Reilly Media, Inc. was aware of a trademark claim, the designations have been printed in caps or initial caps. While every precaution has been taken in the preparation of this book, the publisher and author assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein.