Linux

Ubuntu SNMPD - Localhost MIB-IP and Statistics

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As part of the processing of exploring some infrastructure for my thesis - I noticed that the SNMPD documentation needed some love despite the many eyes of the Internet. Here is how I set snmpd up in Ubuntu 15.10 for localhost access to IP-related information contained within the IP MIB.

Install the following:

sudo apt-get install snmp snmp-mibs-downloader snmpd libsnmp-dev

C UDP Client and Server example

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I recently ran across some code for some students that was terribly written regarding sockets and upon helping them - I realized, that most examples just abhorrently throw all of the required code into the program with no function calls to help segment/make sense of it.

Here is my example programs - note that the actual socket code is wrapped up in socket.c & shared.h:

Quick and Simple Ubuntu DNSmasq & DHCP Router

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While setting up a research network, I needed to setup a router/gateway machine between my network lab and the IT managed network; they require a static MAC and wall-port so they can mantain "security" on their network. To get around this (and is approved because of my lab's status) - I needed to setup a machine that would act as a router. Here is the short and simple method to getting Ubuntu and DNSmasq setup.

Modifying Linux ELF Binaries - Changing Callq Addresses

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For awhile, I have wanted to write a simple tutorial of in-line patching of binaries and in particular, changing the assembly instructions and having a binary skip to whatever function we desire manually. This involves tweaking the callq instruction (call can be altered too, but it refers to a static address vs. a relative address).

Okay so lets get started - this tutorial is written to alter one specific thing and assumes that you have some basic knowledge of assembly & know how to compile basic programs. I am also assuming that you could find strings within binaries and know how to convert values in hexadecimal.

The example to be used in this test application contains a main function, and two functions (function1 and function2) which print different messages. The goal of this exercise is to modify the application AFTER it has been compiled so that function2() is executed instead of function1().

Ubuntu 14.01 Not Recognizing All-in-one SD Card reader

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Interestingly enough, Ubuntu 14.01 was unable to recognize my all-in-one SD card reader (Nextech is the brand) despite working in Windows land. Dmesg output was stating errors and assuming that this is just a generic USB device, I wondered if there was something at play, such as SCSI. I was correct and here are the two changes that are needed to make it work.

sudo apt-get install udisks sg3-utils

Then add the following to /etc/modules.conf

Updating/Compiling OpenDiameter and Basic EAP-MD5 Test

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Recently, I was asked to review, maintain, update and document existing work from the Concordia University in Montreal. In an effort to continue the past OpenDiameter work - here is the current work for 1.0.7i(ish) and documentation.

OpenDiameter 1.0.8 will be available SOON!

Compiling OpenDiameter 1.0.7-j and running the EAP-MD5 test

The code can be built using the following process:

sudo apt-get install libbz2-dev build-essential python python-dev

ACE SSL Errors

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I had to compile a really old version of ACE for my advisor and SSL was being a pain - here is what I did to remove it from the equation without hacking the vanilla ACE wrapper 5.7.5 code

../configure --with-openssl=/usr/local/ssl/--with-openssl-include=/usr/local/ssl/include/ --with-openssl-libdir=/usr/local/ssl/lib/ LDFLAGS=-L/usr/local/ssl/lib/ CFLAGS=-I/usr/local/ssl/include CXXFLAGS="-I/usr/local/ssl/include -L/usr/local/ssl/lib" LIBS=-L/usr/local/ssl/lib --disable-ace-examples --disable-ace-tests

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