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Lesslinux Handbook
lesslinux.com Documentation Handbook Mattias Schlenker INUX August-Bebel-Str. 74 L 04275 Leipzig GERMANY ê [email protected] ESS L Contents 1 About LessLinux and this handbook2 2 LessLinux for users3 3 LessLinux for admins4 3.1 Remote access.......................................4 3.1.1 SSH.........................................4 3.1.2 VNC........................................5 3.1.3 RDP........................................6 3.1.4 Xpra........................................7 3.2 Netbooting LessLinux..................................7 3.2.1 CIFS or NFS boot.................................8 3.2.2 HTTP, FTP or TFTP boot.............................8 3.3 LessLinux as thinclient..................................9 3.3.1 Booting to Remmina...............................9 3.3.2 Booting to an RDP login mask.........................9 3.3.3 Booting to a chooser............................... 10 3.3.4 Using XDMCP.................................. 12 3.3.5 Local printers................................... 12 4 LessLinux for builders and contributors 13 4.1 Preparation........................................ 13 4.1.1 Prepare a drive.................................. 13 4.1.2 Create some directories............................. 14 4.1.3 Download the „sources”............................. 14 4.2 Build the first stage.................................... 14 2 Abstract LessLinux is a free Linux system designed to be light and easily modifiable. It is based on Linux from Scratch and was started by Mattias Schlenker in 2009. Since then it has been used as a base for dozens of security and rescue systems published by computer magazines all over the world. It’s simple architecture makes it easy to build LessLinux based systems for use as thinclient, software deployment or the demonstration of software. This book covers the possibilities of LessLinux and tells you how small changes can make LessLinux the lever you need to move your world. -
Gigabit Ethernet - CH 3 - Ethernet, Fast Ethernet, and Gigabit Ethern
Switched, Fast, and Gigabit Ethernet - CH 3 - Ethernet, Fast Ethernet, and Gigabit Ethern.. Page 1 of 36 [Figures are not included in this sample chapter] Switched, Fast, and Gigabit Ethernet - 3 - Ethernet, Fast Ethernet, and Gigabit Ethernet Standards This chapter discusses the theory and standards of the three versions of Ethernet around today: regular 10Mbps Ethernet, 100Mbps Fast Ethernet, and 1000Mbps Gigabit Ethernet. The goal of this chapter is to educate you as a LAN manager or IT professional about essential differences between shared 10Mbps Ethernet and these newer technologies. This chapter focuses on aspects of Fast Ethernet and Gigabit Ethernet that are relevant to you and doesn’t get into too much technical detail. Read this chapter and the following two (Chapter 4, "Layer 2 Ethernet Switching," and Chapter 5, "VLANs and Layer 3 Switching") together. This chapter focuses on the different Ethernet MAC and PHY standards, as well as repeaters, also known as hubs. Chapter 4 examines Ethernet bridging, also known as Layer 2 switching. Chapter 5 discusses VLANs, some basics of routing, and Layer 3 switching. These three chapters serve as a precursor to the second half of this book, namely the hands-on implementation in Chapters 8 through 12. After you understand the key differences between yesterday’s shared Ethernet and today’s Switched, Fast, and Gigabit Ethernet, evaluating products and building a network with these products should be relatively straightforward. The chapter is split into seven sections: l "Ethernet and the OSI Reference Model" discusses the OSI Reference Model and how Ethernet relates to the physical (PHY) and Media Access Control (MAC) layers of the OSI model. -
BSD – Alternativen Zu Linux
∗BSD { Alternativen zu Linux Karl Lockhoff March 19, 2015 Inhaltsverzeichnis I Woher kommt BSD? I Was ist BSD? I Was ist sind die Unterschiede zwischen FreeBSD, NetBSD und OpenBSD? I Warum soll ich *BSD statt Linux einsetzen? I Chuck Haley und Bill Joy entwickeln den vi in Berkeley I Bill Joy erstellt eine Sammlung von Tools, 1BSD I Unix Version 7 erscheint I 2BSD erscheint (Basis f¨urdie Weiterentwicklung PDP-11) I 3BSD erscheint (erstmalig mit einen eigenen Kernel) I 4BSD erscheint (enth¨altdas fast file system (ffs)) I Bill Joy wechselt zu Sun Microsystems I Kirk McKusick ¨ubernimmt die Entwicklung von BSD I 1978 I 1979 I 1980 I 1981 Woher kommt BSD? I 1976 I Unix Version 6 erscheint I 2BSD erscheint (Basis f¨urdie Weiterentwicklung PDP-11) I 3BSD erscheint (erstmalig mit einen eigenen Kernel) I 4BSD erscheint (enth¨altdas fast file system (ffs)) I Bill Joy wechselt zu Sun Microsystems I Kirk McKusick ¨ubernimmt die Entwicklung von BSD I Bill Joy erstellt eine Sammlung von Tools, 1BSD I Unix Version 7 erscheint I 1979 I 1980 I 1981 Woher kommt BSD? I 1976 I Unix Version 6 erscheint I 1978 I Chuck Haley und Bill Joy entwickeln den vi in Berkeley I 2BSD erscheint (Basis f¨urdie Weiterentwicklung PDP-11) I 3BSD erscheint (erstmalig mit einen eigenen Kernel) I 4BSD erscheint (enth¨altdas fast file system (ffs)) I Bill Joy wechselt zu Sun Microsystems I Kirk McKusick ¨ubernimmt die Entwicklung von BSD I Unix Version 7 erscheint I 1979 I 1980 I 1981 Woher kommt BSD? I 1976 I Unix Version 6 erscheint I 1978 I Chuck Haley und Bill Joy entwickeln den -
Hitchhiker's Guide to Openbsd
Hitchhiker's Guide to OpenBSD Language: en [teams] cs fr nl Hitchhiker's Guide to OpenBSD Other Documents Commonly Encountered Issues Recent updates Upgrade Guide Following -current Following -stable This wholly remarkable guide is supplemental documentation to the even Porter's Handbook more froopy man pages, available both in the installed system and online. Port Testing Guide The Guide covers the active release of OpenBSD, currently v4.9. There are Using AnonCVS likely features and changes to features in the development version (- Using CVSup current) of OpenBSD that are not covered in the Guide. Manual pages Bug Reporting The Guide (cleverly disguised as a FAQ) in PDF and plain text form is Mailing lists available in the pub/OpenBSD/doc directory from many FTP mirrors, PF User's Guide along with archival versions. OpenSSH FAQ So, grab your towel and remember: PDF files OpenBSD FAQ Don't panic! PF User's Guide (We've done our part to keep OpenBSD from doing so!) Text files OpenBSD FAQ PF User's Guide Back to OpenBSD 1 - Introduction to OpenBSD ● 1.1 - What is OpenBSD? ● 1.2 - On what systems does OpenBSD run? ● 1.3 - Why might I want to use OpenBSD? ● 1.4 - Is OpenBSD really free? ● 1.5 - How can I help support OpenBSD? ● 1.6 - Who maintains OpenBSD? ● 1.7 - When is the next release of OpenBSD? ● 1.8 - What is included with OpenBSD? http://www.openbsd.org/faq/index.html (1 of 9)9/4/2011 10:01:39 AM Hitchhiker's Guide to OpenBSD ● 1.9 - What is new in OpenBSD 4.9? ● 1.10 - Can I use OpenBSD as a desktop system? ● 1.11 - Why is/isn't -
ECE 435 – Network Engineering Lecture 15
ECE 435 { Network Engineering Lecture 15 Vince Weaver http://web.eece.maine.edu/~vweaver [email protected] 25 March 2021 Announcements • Note, this lecture has no video recorded due to problems with UMaine zoom authentication at class start time • HW#6 graded • Don't forget HW#7 • Project Topics due 1 RFC791 Post-it-Note Internet Protocol Datagram RFC791 Source Destination If other than version 4, Version attach form RFC 2460. Type of Service Precedence high reliability Routine Fragmentation Offset high throughput Priority Transport layer use only low delay Immediate Flash more to follow Protocol Flash Override do not fragment CRITIC/ECP this bit intentionally left blank TCP Internetwork Control UDP Network Control Other _________ Identifier _______________________ Length Header Length Data Print legibly and press hard. You are making up to 255 copies. _________________________________________________ _________________________________________________ _________________________________________________ Time to Live Options _________________________________________________ Do not write _________________________________________________ in this space. _________________________________________________ _________________________________________________ Header Checksum _________________________________________________ _________________________________________________ for more info, check IPv4 specifications at http://www.ietf.org/rfc/rfc0791.txt 2 HW#6 Review • Header: 0x000e: 4500 = version(4), header length(5)=20 bytes ToS=0 0x0010: 0038 = packet length (56 bytes) 0x0012: 572a = identifier 0x0014: 4000 = fragment 0100 0000 0000 0000 = do not fragment, offset 0 0x0016: 40 = TTL = 64 0x0017: 06 = Upper layer protocol (6=TCP) 0x0018: 69cc = checksum 0x001a: c0a80833 = source IP 192.168.8.51 0x001e: 826f2e7f = dest IP 130.111.46.127 • Valid IPs 3 ◦ 123.267.67.44 = N ◦ 8.8.8.8 = Y ◦ 3232237569 = 192.168.8.1 ◦ 0xc0a80801 = 192.168.8.1 • A class-A allocation is roughly 224=232 which is 0.39% • 192.168.13.0/24. -
NCD Thin Client Xware User's Guide
NCD NCD Thin Client Xware User’s Guide Part Number 5401612 June 1998 Network Computing Devices, Inc. 350 North Bernardo Avenue Mountain View, CA 94043-5207 Technical support: 503/641-2200 Technical support FAX: 503/641-2959 Email: [email protected] World Wide Web: http://www.ncd.com Copyright Copyright © 1998 by Network Computing Devices, Inc. The information contained in this document is subject to change without notice. NCD SHALL NOT BE LIABLE FOR ERRORS CONTAINED HEREIN OR FOR ANY DAMAGES WHATSOEVER, INCLUDING, WITHOUT LIMITATION, ANY INCIDENTAL OR CONSEQUENTIAL DAMAGES IN CONNECTION WITH THE FURNISHING, PERFORMANCE, OR USE OF THIS MATERIAL. This document contains information which is protected by copyright. All rights are reserved. Made in the U.S.A. No part of this document may be photocopied, reproduced, or translated to another language without the prior written consent of NCD. Title to and ownership of the Software, and all copies thereof, shall at all times reside with NCD and its licensors, and is protected by United States copyright laws and international treaty provisions. Trademarks Network Computing Devices is a registered trademark of Network Computing Devices, Inc. NCDnet, NCDware, and Thin Client Xware FTP are trademarks of Network Computing Devices, Inc. Apple and LaserWriter are registered trademarks of Apple Computer, Inc. Citrix, WinFrame, and ICA are registered trademarks of Citrix Systems, Inc. DECnet, DECwindows, VMS, VT, and ULTRIX are trademarks of Digital Equipment Corporation. Ethernet is a trademark of Xerox Corporation. Hewlett-Packard and LaserJet are registered trademarks of Hewlett-Packard Corporation. HP-UX is a trademark of Hewlett-Packard Corporation. -
Ethernet and Wifi
Ethernet and WiFi hp://xkcd.com/466/ CSCI 466: Networks • Keith Vertanen • Fall 2011 Overview • Mul?ple access networks – Ethernet • Long history • Dominant wired technology – 802.11 • Dominant wireless technology 2 Classic Ethernet • Ethernet – luminferous ether through which electromagne?c radiaon once thought to propagate – Carrier Sense, Mul?ple Access with Collision Detec?on (CSMA/CD) – IEEE 802.3 Robert Metcalfe, co- inventor of Ethernet 3 Classic Ethernet • Ethernet – Xerox Ethernet standardized as IEEE 802.3 in 1983 – Xerox not interested in commercializing – Metcalfe leaves and forms 3Com 4 Ethernet connec?vity • Shared medium – All hosts hear all traffic on cable – Hosts tapped the cable – 2500m maximum length – May include repeaters amplifying signal – 10 Mbps bandwidth 5 Classic Ethernet cabling Cable aSer being "vampire" tapped. Thick Ethernet cable (yellow), 10BASE-5 transceivers, cable tapping tool (orange), 500m maximum length. Thin Ethernet cable (10BASE2) with BNC T- connector, 185m maximum length. 6 Ethernet addressing • Media Access Control address (MAC) – 48-bit globally unique address • 281,474,976,710,656 possible addresses • Should last ?ll 2100 • e.g. 01:23:45:67:89:ab – Address of all 1's is broadcast • FF:FF:FF:FF:FF:FF 7 Ethernet frame format • Frame format – Manchester encoded – Preamble products 10-Mhz square wave • Allows clock synch between sender & receiver – Pad to at least 64-bytes (collision detec?on) Ethernet 802.3 AlternaWng 0's 48-bit MAC and 1's (except addresses SoF of 11) 8 Ethernet receivers • Hosts listens to medium – Deliver to host: • Any frame with host's MAC address • All broadcast frames (all 1's) • Mul?cast frames (if subscribed to) • Or all frames if in promiscuous mode 9 MAC sublayer • Media Access Control (MAC) sublayer – Who goes next on a shared medium – Ethernet hosts can sense if medium in use – Algorithm for sending data: 1. -
CSC 405 Computer Security Linux Security
CSC 405 Computer Security Linux Security Alexandros Kapravelos [email protected] Unix / Linux • Started in 1969 at AT&T / Bell Labs • Split into a number of popular branches – BSD, System V (commercial, AT&T), Solaris, HP-UX, AIX • Inspired a number of Unix-like systems – Linux, Minix • Standardization attempts – POSIX, Single Unix Specification (SUS), Filesystem Hierarchy Standard (FHS), Linux Standard Base (LSB), ELF OS Security • Kernel vulnerability – usually leads to complete system compromise – attacks performed via system calls Kernel vulnerabilities Kernel vulnerabilities Kernel exploitation research is active Unleashing Use-Before-Initialization Vulnerabilities in the Linux Kernel Using Targeted Stack Spraying • reliably exploiting uninitialized uses on the kernel stack has been considered infeasible • code executed prior to triggering the vulnerability must leave an attacker-controlled pattern on the stack • a fully automated targeted stackspraying approach for the Linux kernel that reliably facilitates the exploitation of uninitialized uses • published in NDSS 2017 source: https://www.cc.gatech.edu/~klu38/publications/ubi-ndss17.pdf Unix • Code running in user mode is always linked to a certain identity – security checks and access control decisions are based on user identity • Unix is user-centric – no roles • User – identified by username (UID), group name (GID) – typically authenticated by password (stored encrypted) • User root – superuser, system administrator – special privileges (access resources, modify OS) – cannot -
Gigabit Ethernet
Ethernet Technologies and Gigabit Ethernet Professor John Gorgone Ethernet8 Copyright 1998, John T. Gorgone, All Rights Reserved 1 Topics • Origins of Ethernet • Ethernet 10 MBS • Fast Ethernet 100 MBS • Gigabit Ethernet 1000 MBS • Comparison Tables • ATM VS Gigabit Ethernet •Ethernet8SummaryCopyright 1998, John T. Gorgone, All Rights Reserved 2 Origins • Original Idea sprang from Abramson’s Aloha Network--University of Hawaii • CSMA/CD Thesis Developed by Robert Metcalfe----(1972) • Experimental Ethernet developed at Xerox Palo Alto Research Center---1973 • Xerox’s Alto Computers -- First Ethernet Ethernet8systemsCopyright 1998, John T. Gorgone, All Rights Reserved 3 DIX STANDARD • Digital, Intel, and Xerox combined to developed the DIX Ethernet Standard • 1980 -- DIX Standard presented to the IEEE • 1980 -- IEEE creates the 802 committee to create acceptable Ethernet Standard Ethernet8 Copyright 1998, John T. Gorgone, All Rights Reserved 4 Ethernet Grows • Open Standard allows Hardware and Software Developers to create numerous products based on Ethernet • Large number of Vendors keeps Prices low and Quality High • Compatibility Problems Rare Ethernet8 Copyright 1998, John T. Gorgone, All Rights Reserved 5 What is Ethernet? • A standard for LANs • The standard covers two layers of the ISO model – Physical layer – Data link layer Ethernet8 Copyright 1998, John T. Gorgone, All Rights Reserved 6 What is Ethernet? • Transmission speed of 10 Mbps • Originally, only baseband • In 1986, broadband was introduced • Half duplex and full duplex technology • Bus topology Ethernet8 Copyright 1998, John T. Gorgone, All Rights Reserved 7 Components of Ethernet • Physical Medium • Medium Access Control • Ethernet Frame Ethernet8 Copyright 1998, John T. Gorgone, All Rights Reserved 8 CableCable DesignationsDesignations 10 BASE T SPEED TRANSMISSION MAX TYPE LENGTH Ethernet8 Copyright 1998, John T. -
BSD UNIX Toolbox 1000+ Commands for Freebsd, Openbsd
76034ffirs.qxd:Toolbox 4/2/08 12:50 PM Page iii BSD UNIX® TOOLBOX 1000+ Commands for FreeBSD®, OpenBSD, and NetBSD®Power Users Christopher Negus François Caen 76034ffirs.qxd:Toolbox 4/2/08 12:50 PM Page ii 76034ffirs.qxd:Toolbox 4/2/08 12:50 PM Page i BSD UNIX® TOOLBOX 76034ffirs.qxd:Toolbox 4/2/08 12:50 PM Page ii 76034ffirs.qxd:Toolbox 4/2/08 12:50 PM Page iii BSD UNIX® TOOLBOX 1000+ Commands for FreeBSD®, OpenBSD, and NetBSD®Power Users Christopher Negus François Caen 76034ffirs.qxd:Toolbox 4/2/08 12:50 PM Page iv BSD UNIX® Toolbox: 1000+ Commands for FreeBSD®, OpenBSD, and NetBSD® Power Users Published by Wiley Publishing, Inc. 10475 Crosspoint Boulevard Indianapolis, IN 46256 www.wiley.com Copyright © 2008 by Wiley Publishing, Inc., Indianapolis, Indiana Published simultaneously in Canada ISBN: 978-0-470-37603-4 Manufactured in the United States of America 10 9 8 7 6 5 4 3 2 1 Library of Congress Cataloging-in-Publication Data is available from the publisher. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permitted under Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 646-8600. Requests to the Publisher for permis- sion should be addressed to the Legal Department, Wiley Publishing, Inc., 10475 Crosspoint Blvd., Indianapolis, IN 46256, (317) 572-3447, fax (317) 572-4355, or online at http://www.wiley.com/go/permissions. -
Environment Variable and Set-UID Program Lab 1
SEED Labs – Environment Variable and Set-UID Program Lab 1 Environment Variable and Set-UID Program Lab Copyright © 2006 - 2016 Wenliang Du, All rights reserved. Free to use for non-commercial educational purposes. Commercial uses of the materials are prohibited. The SEED project was funded by multiple grants from the US National Science Foundation. 1 Overview The learning objective of this lab is for students to understand how environment variables affect program and system behaviors. Environment variables are a set of dynamic named values that can affect the way running processes will behave on a computer. They are used by most operating systems, since they were introduced to Unix in 1979. Although environment variables affect program behaviors, how they achieve that is not well understood by many programmers. As a result, if a program uses environment variables, but the programmer does not know that they are used, the program may have vulnerabilities. In this lab, students will understand how environment variables work, how they are propagated from parent process to child, and how they affect system/program behaviors. We are particularly interested in how environment variables affect the behavior of Set-UID programs, which are usually privileged programs. This lab covers the following topics: • Environment variables • Set-UID programs • Securely invoke external programs • Capability leaking • Dynamic loader/linker Readings and videos. Detailed coverage of the Set-UID mechanism, environment variables, and their related security problems can be found in the following: • Chapters 1 and 2 of the SEED Book, Computer & Internet Security: A Hands-on Approach, 2nd Edition, by Wenliang Du. -
Mandoc: Becoming the Main BSD Manual Toolbox
mandoc: becoming the main BSD manual toolbox BSDCan 2015, June 13, Ottawa Ingo Schwarze <[email protected]> Cynthia Livingston’sOTTB “Bedifferent” (c) 2013 C. Livingston (with permission) > Ingo Schwarze: mandoc page 2: INTROI BSDCan 2015, June 13, Ottawa Brief history of UNIX documentation • The key point: All documentation in one place and one format. Easy to find, uniform and easy to read and write. Be correct, complete, concise. • 1964: RUNOFF/roffmarkup syntax by Jerome H. Saltzer,MIT. Unobtrusive,diff(1)-friendly,easy to hand-edit, simple tools, high quality output. • 1971: Basic manual structure by Ken Thompson and Dennis Ritchie for the AT&T Version 1 UNIX manuals, Bell Labs. • 1979: man(7) physical markup language for AT&T Version 7 UNIX. • 1989: mdoc(7) semantic markup by Cynthia Livingston for 4.3BSD-Reno. Powerful, self-contained, portable. • 1989: GNU troffbyJames Clarke. • 2001: mdoc(7) rewrite by Werner Lemberg and Ruslan Ermilovfor groff-1.17. • 2008: mandoc(1) started by Kristaps Dzonsons. • 2010: mandoc(1) is the only documentation formatter in the OpenBSD base system. • 2014: mandoc(1) used by default in OpenBSD, FreeBSD, NetBSD, illumos. 16:19:30 What is the mandoc toolbox? → < > Ingo Schwarze: mandoc page 3: INTROIIBSDCan 2015, June 13, Ottawa What is the mandoc toolbox? User perspective:man(1), the manual viewer One comprehensive tool! Normal operation always proceeds in three steps: 1. Find one or more manuals in the file system or using a database by manual name — man(1) — or by search query — apropos(1) =man -k The result of this step can be printed out with man -w.