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TCPDUMP Caution
TCPDUMP q Refer to book ”Open Source Network Administration” m Online sample chapter: http://www.phptr.com/articles/article.asp?p=170902&seqNum=4 q Some tools are not based directly on the data being transmitted on a network, but information related to that data. m For example, network bandwidth values m System logs on network equipment q Sometimes needs to examine the packets themselves. m Diagnose some particularly tricky network problems q Widely used open source tool for directly analyzing packets: tcpdump m http://www.tcpdump.org/ Network Analyzer 1-1 Caution q Before you use tcpdump or other analyzer: m Will be able to see some private data m Consult/research Legal implication first m Respect the privacy of other users Network Analyzer 1-2 1 What Tcpdump can do for you q View the entire data portion of an Ethernet frame or other link layer protocol m An IP packet m An ARP packet m Or any protocol at a higher layer than Ethernet. q Very useful m Tcpdump is to a network administrator like a microscope to a biologist. m Give a very clear picture of a specific part of your network m Can be used when the problem is simply that something is not working properly. Network Analyzer 1-3 What tcpdump can do for you? q Case1 : Web browser can not load pages from a server – it hangs. m Problem with client? Server? Or between? m Run tcpdump while loading • Watch every stage to see the following – DNS query – HTTP request to server – Server respond q Case 2: help debug denial of service attacks. -
I3: Maximizing Packet Capture Performance
I3: Maximizing Packet Capture Performance Andrew Brown Agenda • Why do captures drop packets, how can you tell? • Software considerations • Hardware considerations • Potential hardware improvements • Test configurations/parameters • Performance results Sharkfest 2014 What is a drop? • Failure to capture a packet that is part of the traffic in which you’re interested • Dropped packets tend to be the most important • Capture filter will not necessarily help Sharkfest 2014 Why do drops occur? • Applications don’t know that their data is being captured • Result: Only one chance to capture a packet • What can go wrong? Let’s look at the life of a packet Sharkfest 2014 Internal packet flow • Path of a packet from NIC to application (Linux) • Switch output queue drops • Interface drops • Kernel drops Sharkfest 2014 Identifying drops • Software reports drops • L4 indicators (TCP ACKed lost segment) • L7 indicators (app-level sequence numbers revealed by dissector) Sharkfest 2014 When is (and isn’t) it necessary to take steps to maximize capture performance? • Not typically necessary when capturing traffic of <= 1G end device • More commonly necessary when capturing uplink traffic from a TAP or SPAN port • Some sort of action is almost always necessary at 10G • Methods described aren’t always necessary • Methods focus on free solutions Sharkfest 2014 Software considerations - Windows • Quit unnecessary programs • Avoid Wireshark for capturing ˗ Saves to TEMP ˗ Additional processing for packet statistics • Uses CPU • Uses memory over time, can lead -
PF: the Openbsd Packet Filter
PF: The OpenBSD Packet Filter Languages: [en] [de] [es] [fr] [id] [ja] [pl] [up to FAQ] [Next: Getting Started] PF: The OpenBSD Packet Filter Table of Contents ● Basic Configuration ❍ Getting Started ❍ Lists and Macros ❍ Tables ❍ Packet Filtering ❍ Network Address Translation ❍ Traffic Redirection (Port Forwarding) ❍ Shortcuts For Creating Rulesets ● Advanced Configuration ❍ Runtime Options ❍ Scrub (Packet Normalization) ❍ Anchors and Named (Sub) Rulesets ❍ Packet Queueing and Prioritization ❍ Address Pools and Load Balancing ❍ Packet Tagging ● Additional Topics ❍ Logging ❍ Performance ❍ Issues with FTP ❍ Authpf: User Shell for Authenticating Gateways ● Example Rulesets ❍ Example: Firewall for Home or Small Office Packet Filter (from here on referred to as PF) is OpenBSD's system for filtering TCP/IP traffic and doing Network Address Translation. PF is also capable of normalizing and conditioning TCP/IP traffic and providing bandwidth control and packet prioritization. PF has been a part of the GENERIC OpenBSD kernel since OpenBSD 3.0. Previous OpenBSD releases used a different firewall/NAT package which is no longer supported. PF was originally developed by Daniel Hartmeier and is now maintained and developed by Daniel and the rest of the OpenBSD team. This set of documents is intended as a general introduction to the PF system as run on OpenBSD. It is intended to be used as a supplement to the man pages, not as a replacement for them. This document covers all of PF's major features. For a complete and http://www.openbsd.org/faq/pf/index.html (1 of 2) [02/06/2005 14:54:58] PF: The OpenBSD Packet Filter in-depth view of what PF can do, please start by reading the pf(4) man page. -
Tcpdump Basics
TCPdump Basics What we will cover: What is/are TCPdump/WinDump? Why use TCPdump? Installation of TCPdump on Unix/Windows It’s installed, now what? Changing the amount of data collected Reading TCPdump/WinDump Output TCP Flags in TCPdump/WinDump Absolute & Relative Sequence Numbers Dumping TCPdump/WinDump output in hexadecimal format TCPdump ManPage TCPdump is a tool we can use for packet analysis. We will not use ethereal (wireshark) because it does “too much” for us. TCPdump will keep everything “raw” and that’s the way we like it! *note: it is expected that the reader will try out all the TCPdump/WinDump commands listed in the lesson on their own computers as well as the practical exercises. You have to actually run the commands to learn how to use the tool. What is/are TCPdump/WinDump? TCPdump, and its cousin WinDump, is software that allows us to see inside the traffic activity that occurs on a network. TCPdump is a Unix tool used to gather data from the network, decipher the bits, and display the output in a human readable format (granted it does take a little bit of instruction to learn the TCPdump language). Why use TCPdump? Network traffic travels in data packets; each data packet contains the information that it needs to travel across the network. This information is contained in a TCP header. A TCP header will contain the destination and source address, state information, and protocol identifiers. The rest of the packet contains the data that is being sent. Devices that are responsible for routing read the information in these packets and send them to their correct destination. -
Best Practices in Mobile Application Testing
Innovate, Digitize, Transform BEST PRACTICES IN MOBILE APPLICATION TESTING The basic frame of software testers’ mind-set is attuned to check documentation, functionality, stability, API and performance and make sure that the software application is secure from all vulnerabilities and check for any other related things surrounding the software piece of code. However, mobile application testing adds a different dimension to the traditional software testing in the sense that the testers have to think about the mobile functions based on usage patterns, heterogeneous devices available in the market with different screen sizes and form factors adds to the complexity of the mobile testing. This whitepaper talks about the best practices that exist at ACL Digital pertaining to mobile application testing focusing on mobile apps for iPhone, Android, Windows Phone and mobile web apps. These practices have evolved over a period of time with our experience in working with global top enterprises and ISVs that improved the testing activities and provided a quick turnaround time reducing the cycle time. Functional Testing Every new feature developed for a mobile device needs to be thoroughly tested. Functional testing is an important aspect when it comes to mobile app testing. Based on the developed test cases, mobile testers should do manual and automated testing. At the beginning of the test phase, a tester must test the mobile app manually using “black box” strategy to see if the functionality provided matches to customer expectations and work as designed. Besides traditional software testing defined in text books, like clicking a button, submitting a form, playing around with different screen elements, mobile testers must perform more functional and device-specific testing. -
BSD Projects IV – BSD Certification • Main Features • Community • Future Directions a (Very) Brief History of BSD
BSD Overview Jim Brown May 24, 2012 BSD Overview - 5/24/2012 - Jim Brown, ISD BSD Overview I – A Brief History of BSD III – Cool Hot Stuff • ATT UCB Partnership • Batteries Included • ATT(USL) Lawsuit • ZFS , Hammer • BSD Family Tree • pf Firewall, pfSense • BSD License • Capsicum • Virtualization Topics • Jails, Xen, etc. • Desktop PC-BSD II – The Core BSD Projects IV – BSD Certification • Main Features • Community • Future Directions A (Very) Brief History of BSD 1971 – ATT cheaply licenses Unix source code to many organizations, including UCB as educational material 1975 – Ken Thompson takes a sabbatical from ATT, brings the latest Unix source on tape to UCB his alma mater to run on a PDP 11 which UCB provided. (Industry/academic partnerships were much more common back then.) Computer Science students (notably Bill Joy and Chuck Haley) at UCB begin to make numerous improvements to Unix and make them available on tape as the “Berkeley Software Distribution” - BSD A (Very) Brief History of BSD Some notable CSRG • 1980 – Computer Science Research Group members (CSRG) forms at UCB with DARPA funding to make many more improvements to Unix - job control, autoreboot, fast filesystem, gigabit address space, Lisp, IPC, sockets, TCP/IP stack + applications, r* utils, machine independence, rewriting almost all ATT code with UCB/CSRG code, including many ports • 1991 – The Networking Release 2 tape is released on the Internet via anon FTP. A 386 port quickly follows by Bill and Lynne Jolitz. The NetBSD group is formed- the first Open Source community entirely on the Internet • 1992 – A commercial version, BSDI (sold for $995, 1-800-ITS-UNIX) draws the ire of USL/ATT. -
Performance Evaluation of Tcpdump
Performance Evaluation of Tcpdump Farhan Jiva University of Georgia Abstract performed relatively similar with respect to packet loss. FreeBSD performed the worst out of the op- With the onset of high-speed networks, using erating systems tested, while Windows usually dis- tcpdump in a reliable fashion can become prob- plays seemingly random spikes of packet loss. For lematic when facing the poor performance of mod- each of the datasets we tested, we found that Fedora ern operating systems. Because of this limitation, performs the best. The rest of the paper is laid out the amount of packet loss a user is willing to face as follows: is an important factor when choosing an operating system for a specific task. In this paper, we evaluate the performance of tcpdump on five modern operat- • In Section 2 we discuss some related work. ing systems. 1 Introduction • Section 3 covers our evaluation, along with our experimental setup and experimental results. The reliable usage of tcpdump as a network an- alyzing/debugging/monitoring tool is arguably a non-trivial task. With the onset of high-speed net- • In Section 4, we discuss our conclusions. works, using tcpdump in a reliable fashion can become problematic when facing the poor perfor- mance of modern operating systems. It is because of this limitation that the amount of packet loss be- 2 Related Work comes an inevitable factor when choosing an oper- ating system for a specific task. For example, a re- One approach to increasing the performance of searcher who needs to extract binary executable files packet capturing is explained by Deri et al. -
BERKELEY PACKET FILTER: Theory, Practice and Perspectives
Alma Mater Studiorum · Universita` di Bologna SCUOLA DI SCIENZE Corso di Laurea in Informatica BERKELEY PACKET FILTER: theory, practice and perspectives Relatore: Presentata da: Chiar.mo Prof. MICHELE DI STEFANO RENZO DAVOLI Sessione II Anno Accademico 2019/2020 All operating systems sucks, but Linux just sucks less. Linus Torvalds Introduction Initially packet filtering mechanism in many Unix versions was imple- mented in the userspace, meaning that each packet was copied from the kernel-space to the user-space before being filtered. This approach resulted to be inefficient compared with the performance shown by the introduction of the BSD classic Berkeley Packet Filter (cBPF). cBPF consists of an as- sembly language for a virtual machine which resides inside the kernel. The assembly language can be used to write filters that are loaded in to the ker- nel from the user-space allowing the filtering to happen in the kernel-space without copying each packet as before. cBPF use is not limited to just the networking domain but it is also applied as a mechanism to filter system calls through seccomp mode. Seccomp allows the programmer to arbitrary select which system calls to permit, representing an useful mechanism to implement sandboxing. In order to increase the number of use cases and to update the architecture accordingly to new advancements in modern processors, the virtual machine has been rewritten and new features have been added. The result is extended Berkeley Packet Filter (eBPF) which consists of a richer assembly, more pro- gram types, maps to store key/value pairs and more components. Currently eBPF (or just BPF) is under continuous development and its capacities are evolving, although the main uses are networking and tracing. -
<[email protected]> Asiabsdcon 2012 Tokyo University of Science, Tokyo, Japan 22
<unnamed>: mpd304-L1-lt: mpd294-lso: mpd294-eso: mpd294-cso: mpd304-eso: mpd304-cso: ngctl306: ksocket [11]: tee [d]: socket [3]: socket [5]: socket [4]: socket [c]: socket [b]: socket [13]: <unnamed>: mpd304-lso: inet/dgram/udp left2right l2tp [f]: socket [a]: <unnamed>: lower ctrl l0 socket [e]: ctrl Introduction to NETGRAPH on FreeBSD Systems Dr. Adrian Steinmann <[email protected]> AsiaBSDCon 2012 Tokyo University of Science, Tokyo, Japan 22 – 25 March, 2012 Tutorial Materials Extended Abstract Tutorial Slides ʻAll About Netgraphʼ man 8 ngctl man 8 nghook man 4 netgraph About Myself Ph.D. in Mathematical Physics (long time ago) Webgroup Consulting AG (now) IT Consulting: Open Source, Security, Perl FreeBSD since version 1.0 (1993) NetBSD since version 3.0 (2005) Traveling, Sculpting, Go Tutorial Outline (1) Netgraph in a historical context (2) Getting to know netgraph (3) Working with netgraph (4) Details of frequently used netgraph node types (5) Examples using netgraph nodes as building blocks (6) Investigate some more sophisticated examples (7) Guidelines for implementing custom node types What is Netgraph Netgraph is in-kernel ‘network plumbing’ Drawn as a graph, a communication protocol can be seen as data packets flowing (bidirectionally) along the edges (lines) between nodes where the packets are processed. In FreeBSD since version 3.0 (2000) Created on FreeBSD 2.2 (1996) by Archie Cobbs <[email protected]> and Julian Elischer <[email protected]> for the Whistle InterJet at Whistle Communications, Inc. Ancient History Dennis Ritchie -
The Book of PF Covers the Most • Stay in Control of Your Traffic with Monitoring and Up-To-Date Developments in PF, Including New Content PETER N.M
EDITION3RD BUILD A Covers OpenBSD 5.6, MORE SECURE FreeBSD 10.x, and NETWORK EDITION NETWORK 3RD NetBSD 6.x WITH PF THETHE BOOKBOOK THE BOOK OF PF OF THE BOOK THE BOOK OF PF OF THE BOOK OFOF PFPF OpenBSD’s stateful packet filter, PF, is the heart of • Build adaptive firewalls to proactively defend against A GUIDE TO THE the OpenBSD firewall. With more and more services attackers and spammers NO-NONSENSE placing high demands on bandwidth and an increas- OPENBSD FIREWALL • Harness OpenBSD’s latest traffic-shaping system ingly hostile Internet environment, no sysadmin can to keep your network responsive, and convert your afford to be without PF expertise. existing ALTQ configurations to the new system The third edition of The Book of PF covers the most • Stay in control of your traffic with monitoring and up-to-date developments in PF, including new content PETER N.M. HANSTEEN visualization tools (including NetFlow) on IPv6, dual stack configurations, the “queues and priorities” traffic-shaping system, NAT and redirection, The Book of PF is the essential guide to building a secure wireless networking, spam fighting, failover provision- network with PF. With a little effort and this book, you’ll ing, logging, and more. be well prepared to unlock PF’s full potential. You’ll also learn how to: ABOUT THE AUTHOR • Create rule sets for all kinds of network traffic, whether Peter N.M. Hansteen is a consultant, writer, and crossing a simple LAN, hiding behind NAT, traversing sysadmin based in Bergen, Norway. A longtime DMZs, or spanning bridges or wider networks Freenix advocate, Hansteen is a frequent lecturer on OpenBSD and FreeBSD topics, an occasional • Set up wireless networks with access points, and contributor to BSD Magazine, and the author of an lock them down using authpf and special access often-slashdotted blog (http://bsdly.blogspot.com/ ). -
Problem Solving and Troubleshooting in AIX 5L
Front cover Problem Solving and Troubleshooting in AIX 5L Introduction of new problem solving tools and changes in AIX 5L Step by step troubleshooting in real environments Complete guide to the problem determination process HyunGoo Kim JaeYong An John Harrison Tony Abruzzesse KyeongWon Jeong ibm.com/redbooks International Technical Support Organization Problem Solving and Troubleshooting in AIX 5L January 2002 SG24-5496-01 Take Note! Before using this information and the product it supports, be sure to read the general information in “Special notices” on page 439. Second Edition (January 2002) This edition applies to IBM ^ pSeries and RS/6000 Systems for use with the AIX 5L Operating System Version 5.1 and is based on information available in August, 2001. Comments may be addressed to: IBM Corporation, International Technical Support Organization Dept. JN9B Building 003 Internal Zip 2834 11400 Burnet Road Austin, Texas 78758-3493 When you send information to IBM, you grant IBM a non-exclusive right to use or distribute the information in any way it believes appropriate without incurring any obligation to you. © Copyright International Business Machines Corporation 1999-2002. All rights reserved. Note to U.S Government Users – Documentation related to restricted rights – Use, duplication or disclosure is subject to restrictions set forth in GSA ADP Schedule Contract with IBM Corp. Contents Figures . xiii Tables . xv Preface . xvii The team that wrote this redbook. xvii Special notice . xix IBM trademarks . xix Comments welcome. xix Chapter 1. Problem determination introduction. 1 1.1 Problem determination process . 3 1.1.1 Defining the problem . 3 1.1.2 Gathering information from the user . -
Distimo Report
REPORT June 2010 Apple App Store, BlackBerry App World, Google Android Market, Nokia Ovi Store, Palm App Catalog and Windows Marketplace New and noteworthy This report covers the Apple App Store for iPad, the Apple App Store for iPhone, BlackBerry App World (Worldwide), Google Android Market, Nokia Ovi Store, Palm App Catalog and Windows Marketplace for Mobile for May 2010 in the United States. The major findings are: » More than 50% of applications are priced below or equal to $2.00 in all stores, with the exception of BlackBerry App World and Windows Marketplace for Mobile. » The average price of all paid applications and the 100 most popular paid applications in the Apple App Store for iPad ($4.65) is higher than in the Apple App Store for iPhone ($4.01). However, the average price of the 100 top grossing applications is higher on the Apple App Store for iPhone. » Google Android Market has the largest share of free applications (57%) and Windows Marketplace for Mobile has the smallest (22%). » Twitter, Inc. published their native application in the Apple App Store and Google Android Market, becoming the monthly number 10 free application in the Apple App Store for iPhone, and the number 6 free application in Google Android Market. » Nine out of the ten most popular free applications and eight out of ten most popular paid applications in the Apple App Store for iPhone are games. » In the competitive e-reader market, both the iBooks application by Apple, Inc., and the Kindle application by Amazon.com are ranked among the 10 most popular free applications in the Apple App Store for iPad.