Introduction:

As a person with a Computer Networking background, IP utility is one of the most common tools I use on a day to day basis. This utility is crucial in troubleshooting routing issues. It also plays a significant role in understanding the packet traversal from source to destination, specifically answering the questions like which interface is chosen for packet traversal, which device is the source directly connected to, the IP addresses present on its interfaces, and so on. This article provides an overview of typical use-cases for IP utility and the options to be passed.

Basic Options:

ip utility is a part of the iproute2 package and comes pre-installed on all modern Linux distributions. ip utility can be considered as a replacement(also enhancement) for the ifconfig utility which is part of the net-tools package. With advancements in Linux kernel, the net-tools package is being deprecated and a more powerful alternative has evolved. …

Introduction:

Creating links is a common practice in a Linux based Operating system. They make it easy to access a specific file from multiple locations on the file system. I believe that soft links are more commonly used than hard links. The difference between the two types of links will be discussed below.

Types of Links:

Links are broadly categorized into two types. Although they seem to be similar at first, just serving as shortcuts, the underlying implementation details are different.

• Soft Links (Symbolic Links)
• Hard Links

To understand more about the differences, let’s get acquainted with inodes. In a Unix-like file system, everything is a file. A file is a link to an inode. …

Introduction:

File Permissions are a crucial entity in the Linux File System. They decide if a specific user can create, edit, delete, or execute a file. Understanding basic file permissions in Linux and types of ownership (user, group, other) is important to understand the concepts of this article better. If you want a quick recap or a brief introduction to the basic file permissions, please have a look at this article.

Topics covered below:

• SGID
• sticky bit
• takeaways
• limitations

SUID:

The setUID (suid) is a flag that enables users running a script, to inherit the owner’s privileges when executing that script. It can also be considered as a way to temporarily escalate the privileges of a user to perform specific tasks that only privileged users can do. …

Introduction:

I have recently come across inotifywait and iwatch, the real-time file monitoring tools. I am familiar with inodes to some extent but didn’t come across inotify before, until recently. Both of these tools are very powerful and are of high value when it comes to File System Monitoring. I have learned some cool things about these two tools, which use the inotify API internally.

This article is an introduction to inotify and the tools that use inotify like iwatch, and inotify-tools. …

Introduction:

Netcat is regarded as TCP/IP Swiss Army Knife. It is a command-line utility that is so simple yet powerful and can perform operations related to Transmission Control Protocol (TCP), User Data Protocol (UDP). It has an additional capability of being a reliable back-end tool that can be used by other scripts.

It is a feature-rich network debugging and exploration tool, since it can create almost any kind of connection you would need and has several interesting built-in capabilities. — man page

Installation:

Netcat (short for NC) can be installed with the command below. The example below is for Debian-based Operating systems.

apt-get install…

Introduction:

We come across situations where a specific set of binaries can only be run as a privileged user. There can be use-cases where a user or a group of users, without root privileges, have to run these binaries.

One example is the tcpdump network utility. tcpdump can only be run with root privileges. To make such utilities accessible to regular users, proper file capabilities have to set. This article provides information on the following topics

• Understanding what file capabilities are
• A brief overview of the evolution of file capabilities
• Required Capabilities to run certain network utilities

Evolution of File Capabilities:

Traditionally for performing permission checks, each Linux process is categorized into one of the two…

Introduction:

cURL ( stands for Client URL) is a software that provides a library libcurl and command-line tool curl. The features and support that it provides are way overwhelming, there are so many options that can be passed to it, sometimes you are just lost in the man page.

This article aims at providing the commands that are frequently used and as a handy reference and is specific to HTTP/HTTPS protocols. This is no replacement to the man page, it’s more like the highlights of it.

curl is a tool to transfer data from or to a server, using one of the supported protocols (DICT, FILE, FTP, FTPS, GOPHER, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, POP3, POP3S, RTMP, RTSP, SCP, SFTP, SMB, SMBS, SMTP, SMTPS, TELNET, and TFTP). The command is designed to work without user interaction. …

Introduction and Background:

You are in trouble if your HTTP server greets you with a 599:Network Connection Timed out Error. The first thing to check is if the server is reachable and you can SSH into it. Then comes to the rescue, the log file of the server. They would most likely look something like this.

HTTP: Accept error: accept tcp [::]:<port_number>: accept4: too many open files

One might wonder, what has too many open files got to deal with HTTP accept error. The reasoning behind this is quite interesting. Every socket in Debian is treated as an open file. That’s how they are related! …