Lab 4: Socket Programming: Netcat Part
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Netcat and Trojans/Backdoors
Netcat and Trojans/Backdoors ECE4883 – Internetwork Security 1 Agenda Overview • Netcat • Trojans/Backdoors ECE 4883 - Internetwork Security 2 Agenda Netcat • Netcat ! Overview ! Major Features ! Installation and Configuration ! Possible Uses • Netcat Defenses • Summary ECE 4883 - Internetwork Security 3 Netcat – TCP/IP Swiss Army Knife • Reads and Writes data across the network using TCP/UDP connections • Feature-rich network debugging and exploration tool • Part of the Red Hat Power Tools collection and comes standard on SuSE Linux, Debian Linux, NetBSD and OpenBSD distributions. • UNIX and Windows versions available at: http://www.atstake.com/research/tools/network_utilities/ ECE 4883 - Internetwork Security 4 Netcat • Designed to be a reliable “back-end” tool – to be used directly or easily driven by other programs/scripts • Very powerful in combination with scripting languages (eg. Perl) “If you were on a desert island, Netcat would be your tool of choice!” - Ed Skoudis ECE 4883 - Internetwork Security 5 Netcat – Major Features • Outbound or inbound connections • TCP or UDP, to or from any ports • Full DNS forward/reverse checking, with appropriate warnings • Ability to use any local source port • Ability to use any locally-configured network source address • Built-in port-scanning capabilities, with randomizer ECE 4883 - Internetwork Security 6 Netcat – Major Features (contd) • Built-in loose source-routing capability • Can read command line arguments from standard input • Slow-send mode, one line every N seconds • Hex dump of transmitted and received data • Optional ability to let another program service established connections • Optional telnet-options responder ECE 4883 - Internetwork Security 7 Netcat (called ‘nc’) • Can run in client/server mode • Default mode – client • Same executable for both modes • client mode nc [dest] [port_no_to_connect_to] • listen mode (-l option) nc –l –p [port_no_to_connect_to] ECE 4883 - Internetwork Security 8 Netcat – Client mode Computer with netcat in Client mode 1. -
Netcat Starter
www.allitebooks.com Instant Netcat Starter Learn to harness the power and versatility of Netcat, and understand why it remains an integral part of IT and Security Toolkits to this day K.C. Yerrid BIRMINGHAM - MUMBAI www.allitebooks.com Instant Netcat Starter Copyright © 2013 Packt Publishing All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews. Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author, nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book. Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information. First published: January 2013 Production Reference: 1170113 Published by Packt Publishing Ltd. Livery Place 35 Livery Street Birmingham B3 2PB, UK. ISBN 978-1-84951-996-0 www.packtpub.com www.allitebooks.com Credits Author Project Coordinators K.C. "K0nsp1racy" Yerrid Shraddha Bagadia Esha Thakker Reviewer Jonathan Craton Proofreader Kelly Hutchison IT Content and Commissioning Editor Graphics Grant Mizen Aditi Gajjar Commissioning Editor Production Coordinator Priyanka Shah Melwyn D'sa Technical Editor Cover Work Ameya Sawant Melwyn D'sa Copy Editor Cover Image Alfida Paiva Conidon Miranda www.allitebooks.com About the author K.C. -
Singularityce User Guide Release 3.8
SingularityCE User Guide Release 3.8 SingularityCE Project Contributors Aug 16, 2021 CONTENTS 1 Getting Started & Background Information3 1.1 Introduction to SingularityCE......................................3 1.2 Quick Start................................................5 1.3 Security in SingularityCE........................................ 15 2 Building Containers 19 2.1 Build a Container............................................. 19 2.2 Definition Files.............................................. 24 2.3 Build Environment............................................ 35 2.4 Support for Docker and OCI....................................... 39 2.5 Fakeroot feature............................................. 79 3 Signing & Encryption 83 3.1 Signing and Verifying Containers.................................... 83 3.2 Key commands.............................................. 88 3.3 Encrypted Containers.......................................... 90 4 Sharing & Online Services 95 4.1 Remote Endpoints............................................ 95 4.2 Cloud Library.............................................. 103 5 Advanced Usage 109 5.1 Bind Paths and Mounts.......................................... 109 5.2 Persistent Overlays............................................ 115 5.3 Running Services............................................. 118 5.4 Environment and Metadata........................................ 129 5.5 OCI Runtime Support.......................................... 140 5.6 Plugins................................................. -
Netcat − Network Connections Made Easy
Netcat − network connections made easy A lot of the shell scripting I do involves piping the output of one command into another, such as: $ cat /var/log/messages | awk '{print $4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14,$15}' | sed −e 's/\[[0−9]*\]:/:/' | sort | uniq | less which shows me the system log file after removing the timestamps and [12345] pids and removing duplicates (1000 neatly ordered unique lines is a lot easier to scan than 6000 mixed together). The above technique works well when all the processing can be done on one machine. What happens if I want to somehow send this data to another machine right in the pipe? For example, instead of viewing it with less on this machine, I want to somehow send the output to my laptop so I can view it there. Ideally, the command would look something like: $ cat /var/log/messages | awk '{print $4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14,$15}' | sed −e 's/\[[0−9]*\]:/:/' | sort | uniq | laptop That exact syntax won't work because the shell thinks it needs to hand off the data to a program called laptop − which doesn't exist. There's a way to do it, though. Enter Netcat Netcat was written 5 years ago to perform exactly this kind of magic − allowing the user to make network connections between machines without any programming. Let's look at some examples of how it works. Let's say that I'm having trouble with a web server that's not returning the content I want for some reason. -
Lab Work 06. Linux Shell. Files Globbing & Streams Redirection
LAB WORK 06. LINUX SHELL. FILES GLOBBING & STREAMS REDIRECTION. 1. PURPOSE OF WORK • Learn to use shell file globbing (wildcard); • Learn basic concepts about standard UNIX/Linux streams redirections; • Acquire skills of working with filter-programs. • Get experience in creating composite commands that have a different functional purpose than the original commands. 2. TASKS FOR WORK NOTE. Start Your UbuntuMini Virtual Machine on your VirtualBox. You need only Linux Terminal to complete the lab tasks. Before completing the tasks, make a Snapshot of your Virtual Linux. If there are problems, you can easily go back to working condition! 2.0. Create new User account for this Lab Work. • Login as student account (user with sudo permissions). • Create new user account, example stud. Use adduser command. (NOTE. You can use the command “userdel –rf stud” to delete stud account from your Linux.) $ sudo adduser stud • Logout from student account (logout) and login as stud. 2.1. Shell File Globbing Study. 2.2. File Globbing Practice. (Fill in a Table 1 and Table 2) 2.3. Command I/O Redirection Study. 2.4. Redirection Practice. (Fill in a Table 3 and Table 4) © Yuriy Shamshin, 2021 1/20 3. REPORT Make a report about this work and send it to the teacher’s email (use a docx Report Blank). REPORT FOR LAB WORK 06: LINUX SHELL. FILES GLOBBING & STREAMS REDIRECTION Student Name Surname Student ID (nV) Date 3.1. Insert Completing Table 1. File globbing understanding. 3.2. Insert Completing Table 2. File globbing creation. 3.3. Insert Completing Table 3. Command I/O redirection understanding. -
Steering Connections to Sockets with BPF Socket Lookup Hook
Steering connections to sockets with BPF socket lookup hook Jakub Sitnicki, Cloudflare @jkbs0 @cloudflare October 28-29, 2020 Who am I? ● Software Engineer at Cloudflare Spectrum TCP/UDP reverse proxy, Linux kernel, ... ● Contributor to Linux kernel networking & BPF subsystems Goal Run a TCP echo service on ports 7, 77, and 777 … using one TCP listening socket. Fun? We will need… ❏ VM running Linux kernel 5.9+ ❏ bpftool 5.9+ ❏ libbpf headers ❏ kernel headers vm $ uname -r 5.9.1-36.vanilla.1.fc32.x86_64 vm $ bpftool version bpftool v5.9.1 Code and instructions at https://github.com/jsitnicki/ebpf-summit-2020 We will need… a TCP echo server $ sudo dnf install nmap-ncat $ nc -4kle /bin/cat 127.0.0.1 7777 & Netcat + /bin/cat [1] 1289 $ ss -4tlpn sport = 7777 State Recv-Q Send-Q Local Address:Port Peer Address:Port Process LISTEN 0 10 127.0.0.1:7777 0.0.0.0:* users:(("nc",pid=1289,fd=3)) $ nc -4 127.0.0.1 7777 hello⏎ Test it! hello ^D Check open ports on VM external IP vm $ ip -4 addr show eth0 check VM IP 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000 inet 192.168.122.221/24 brd 192.168.122.255 scope global dynamic noprefixroute eth0 valid_lft 2563sec preferred_lft 2563sec host $ nmap -sT -p 1-1000 192.168.122.221 … Not shown: 999 closed ports scan first 1000 ports PORT STATE SERVICE 22/tcp open ssh 7, 77, 777 are closed Nmap done: 1 IP address (1 host up) scanned in 0.07 seconds What is socket lookup? socket receive Application buffer socket Receive path for local delivery lookup Protocol filter INPUT Network raw mangle nat routing conntrack forward PREROUTING PREROUTING PREROUTING decision TC Ring alloc_skb XDP ingress Buffer Driver Wikipedia - Packet flow in Netfilter and General Networking Service dispatch with BPF socket lookup packet metadata BPF program lookup result struct bpf_sk_lookup { (1) 010 (4) __u32 family; 101 Ncat socket 010 __u32 protocol; __u32 remote_ip4; (2) is (3) pick __u32 remote_port; local port echo service __u32 local_ip4; open? socket __u32 local_port; /* .. -
CS2043 - Unix Tools & Scripting Cornell University, Spring 20141
CS2043 - Unix Tools & Scripting Cornell University, Spring 20141 Instructor: Bruno Abrahao January 31, 2014 1 Slides evolved from previous versions by Hussam Abu-Libdeh and David Slater Instructor: Bruno Abrahao CS2043 - Unix Tools & Scripting Vim: Tip of the day! Line numbers Displays line number in Vim: :set nu Hides line number in Vim: :set nonu Goes to line number: :line number Instructor: Bruno Abrahao CS2043 - Unix Tools & Scripting Counting wc How many lines of code are in my new awesome program? How many words are in this document? Good for bragging rights Word, Character, Line, and Byte count with wc wc -l : count the number of lines wc -w : count the number of words wc -m : count the number of characters wc -c : count the number of bytes Instructor: Bruno Abrahao CS2043 - Unix Tools & Scripting Sorting sort Sorts the lines of a text file alphabetically. sort -ru file sorts the file in reverse order and deletes duplicate lines. sort -n -k 2 -t : file sorts the file numerically by using the second column, separated by a colon Example Consider a file (numbers.txt) with the numbers 1, 5, 8, 11, 62 each on a separate line, then: $ sort numbers.txt $ sort numbers.txt -n 1 1 11 5 5 8 62 11 8 62 Instructor: Bruno Abrahao CS2043 - Unix Tools & Scripting uniq uniq uniq file - Discards all but one of successive identical lines uniq -c file - Prints the number of successive identical lines next to each line Instructor: Bruno Abrahao CS2043 - Unix Tools & Scripting Character manipulation! The Translate Command tr [options] <char_list1> [char_list2] Translate or delete characters char lists are strings of characters By default, searches for characters in char list1 and replaces them with the ones that occupy the same position in char list2 Example: tr 'AEIOU' 'aeiou' - changes all capital vowels to lower case vowels Instructor: Bruno Abrahao CS2043 - Unix Tools & Scripting Pipes and redirection tr only receives input from standard input (stdin) i.e. -
Week 2: Networking Lab
Week 2: Networking Lab Topics: I. Netcat II. Nmap III. Wireshark Setup 1. SSH Client If you completed this step in the previous lab, you can skip this step. Once you are in the lab, you will need to get access to the Wi-Fi, and you will need a SSH client installed on your laptop. The lab Wi-Fi password will be up on the board, so you can use that to get access to the Wi-Fi. If you are on a Mac or have Linux installed, a SSH client should already be installed. If your laptop is running Windows, though, you will need to install putty (a windows SSH client). Its installer can be found at the below URL: https://www.chiark.greenend.org.uk/~sgtatham/putty/latest.html Now that everything is set up, SSH into the lab1 server. On Mac/Linux, type the following into your terminal ssh [email protected] Substitute your username for “user1” and it should work out On windows, start up putty, and enter the following into the “Host Name (or IP Address)” Field [email protected] -
Mac OS X Server
Mac OS X Server Version 10.4 Technology Overview August 2006 Technology Overview 2 Mac OS X Server Contents Page 3 Introduction Page 5 New in Version 10.4 Page 7 Operating System Fundamentals UNIX-Based Foundation 64-Bit Computing Advanced BSD Networking Architecture Robust Security Directory Integration High Availability Page 10 Integrated Management Tools Server Admin Workgroup Manager Page 14 Service Deployment and Administration Open Directory Server File and Print Services Mail Services Web Hosting Enterprise Applications Media Streaming iChat Server Software Update Server NetBoot and NetInstall Networking and VPN Distributed Computing Page 29 Product Details Page 31 Open Source Projects Page 35 Additional Resources Technology Overview 3 Mac OS X Server Introduction Mac OS X Server version 10.4 Tiger gives you everything you need to manage servers in a mixed-platform environment and to con gure, deploy, and manage powerful network services. Featuring the renowned Mac OS X interface, Mac OS X Server streamlines your management tasks with applications and utilities that are robust yet easy to use. Apple’s award-winning server software brings people and data together in innovative ways. Whether you want to empower users with instant messaging and blogging, gain greater control over email, reduce the cost and hassle of updating software, or build your own distributed supercomputer, Mac OS X Server v10.4 has the tools you need. The Universal release of Mac OS X Server runs on both Intel- and PowerPC-based The power and simplicity of Mac OS X Server are a re ection of Apple’s operating sys- Mac desktop and Xserve systems. -
TCP/IP Attack Lab 1
SEED Labs – TCP/IP Attack Lab 1 TCP/IP Attack Lab Copyright c 2006 - 2016 Wenliang Du, Syracuse University. The development of this document was partially funded by the National Science Foundation under Award No. 1303306 and 1318814. This work is licensed under a Creative Commons Attribution-NonCommercial- ShareAlike 4.0 International License. A human-readable summary of (and not a substitute for) the license is the following: You are free to copy and redistribute the material in any medium or format. You must give appropriate credit. If you remix, transform, or build upon the material, you must distribute your contributions under the same license as the original. You may not use the material for commercial purposes. 1 Lab Overview The learning objective of this lab is for students to gain first-hand experience on vulnerabilities, as well as on attacks against these vulnerabilities. Wise people learn from mistakes. In security education, we study mistakes that lead to software vulnerabilities. Studying mistakes from the past not only help students understand why systems are vulnerable, why a seemly-benign mistake can turn into a disaster, and why many security mechanisms are needed. More importantly, it also helps students learn the common patterns of vulnerabilities, so they can avoid making similar mistakes in the future. Moreover, using vulnerabilities as case studies, students can learn the principles of secure design, secure programming, and security testing. The vulnerabilities in the TCP/IP protocols represent a special genre of vulnerabilities in protocol de- signs and implementations; they provide an invaluable lesson as to why security should be designed in from the beginning, rather than being added as an afterthought. -
Cyber502x Computer Forensics
CYBER502x Computer Forensics Unit 2: Linux/Unix Forensics Acquisition CYBER 502x Computer Forensics | Yin Pan Investigating Linux/Unix systems • Four basic forensics steps • Collect • Preserve • Analyze • Present (report) CYBER 502x Computer Forensics | Yin Pan Preparation • A tool box (CD or USB) containing trusted forensic tools • A powerful machine with forensic tools installed and clean-wiped hard drive to store acquired evidence. CYBER 502x Computer Forensics | Yin Pan Remember! • Always have your OWN tool sets ready !! • You are dealing with a compromised system • Run tools from your own USB or device • Save the output outside of the compromised system CYBER 502x Computer Forensics | Yin Pan Forensics tools in common • Ensure forensically-sound operations • Process data structure from the image bypassing kernel’s support • Work on both images and live systems CYBER 502x Computer Forensics | Yin Pan Basic imaging steps • Obtain volatile data (including RAM) –According to policy and the case nature • Acquire non-volatile data (image drives and removable media) CYBER 502x Computer Forensics | Yin Pan Acquire volatile information • System information • Memory usage • Running processes • Logged in users • Network connections • Network interface configuration (promiscuous mode?) • …. CYBER 502x Computer Forensics | Yin Pan Volatile Evidence • Most volatile Least volatile Nonvolatile • Memory • Swap space or gagefile • Network status and connections • Processes running • File opening • Hard drive media • Removable media (CD, Zip, USB, -
Unix, Standard I/O and Command Line Arguments Overview Redirection
Unix, Standard I/O and command line arguments For any programming assignments I give you, I expect a program that reads and writes to standard input and output, taking any extra parameters from the command line. This handout explains how to do that. I have also appended a small appendix of useful Unix commands. I recommend that you go to a Unix terminal and type in and run all of the examples in the gray boxes. You can do this from the Terminal application on a MacIntosh, or from a terminal window in GNU/Linux or any Unix-like operating system, from Cygwin in Windows maybe, or by connecting to bingsuns using SSH. Overview Most programming languages feature “standard,” or default, input and output channels where I/O goes unless otherwise specified. In C, the functions scanf(), gets() and getchar() read from standard input, while printf(), puts() and putchar() write to standard output. In Tcl, the gets and puts commands read and write standard input and output. In awk and perl, you just sort of use the force and your program receives a line of input from somewhere. Letʼs stick with C for the time being.1 When a program runs from a terminal, standard input is usually the userʼs keyboard input, while standard output is displayed as text on-screen. Unix and Unix-like operating systems allow you to intercept the standard I/O channels of a program to redirect them into files or other programs. This gives you the ability to chain many simple programs to do something genuinely useful.