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Security Update – scp

Post Written by
Ivan Dabić

Reading time: 1 minute

OpenSSH project had been working on version OpenSSH 8.0p1 in 2019 when they published that “scp” protocol thus the “scp” command has a vulnerability with verification of the file name sent by server against the one that client actually requested. This issue was mitigated in OpenSSH 8.0p1 but, was never fully applied across the platforms.Reference: https://lists.mindrot.org/pipermail/openssh-unix-dev/2019-March/037672.html An…

Zero bytes responses – cache or not to cache?

Post Written by
Ivan Dabić
Last modified on June 30th, 2020 at 9:01 am

Reading time: 4 minutes

Should 0 bytes responses be cached or not (on middle points like CDN or other proxies) is a problem that can be addressed by two entities: RFC Client’s request For client’s request to be met it’s assumed that #1 is honored. What RFC says for 0 bytes caching, basically, is that if a file (or…

Log checking with GREP and AWK

Post Written by
Ivan Dabić
Last modified on June 30th, 2020 at 10:42 am

Reading time: 5 minutes

Most of the time when checking logs we’re presented with a lot of data we may necessarily not need, or we have to manipulate it in some way or present it to a client in a specific way. All of that can be done using a scripting language or utilizing AWK right from the terminal…

Wildcard purge nginx cache

Post Written by
Ivan Dabić
Last modified on June 30th, 2020 at 1:51 pm

Reading time: 7 minutes

Looking for a good solution, at least for my use case, I’ve stumbled upon interesting approach to find and remove nginx cached files by regex pattern. This is proxy_pass or fastcgi cached files, regardless. Repository with source code can be found on github: https://github.com/perusio/nginx-cache-purge The script gets the arguments from regular expression to calculate the match within…

A glance into the reverse proxy setup with nginx

Post Written by
Ivan Dabić
Last modified on July 1st, 2020 at 11:07 am

Reading time: 5 minutes

Reverse proxy Hey all! I wanted to give a short (really short) intro to reverse proxy and how common use case is configured with nginx as a reverse proxy. Tried to keep it short as much as possible. Difference between proxy and reverse proxy Proxy is used to route requests to a well-known endpoint even…

How to change private ssh key password

Post Written by
Ivan Dabić
Last modified on June 29th, 2020 at 3:56 pm

Reading time: 11 minutes

The goal of this article is to describe the process behind changing the passphrase used to generate ssh key pair (private and public) due to security policies or other scenarios where passphrase tends to be a liability in strictly security sense of the word. When the ssh key is generated and passphrase selected, as a…

Linux System Overview using top command

Post Written by
Ivan Dabić
Last modified on June 26th, 2020 at 1:31 pm

Reading time: 4 minutes

top, iotop, iostat and many other commands are used on daily basis to help sysadmins keep the system up and running at all times. It seemed appropriate to bring up the top command overview closer for it to serve as a cheat sheet for most juniors in this industry. Top is used to show the system…

Slack slash commands – adding new slash commands with Wunderground API

Post Written by
Marko Marjanović
Last modified on July 1st, 2020 at 11:13 am

Reading time: 7 minutes

Slack slash commands Before we configure and build our slash command, it’s important to cover some basic concepts and requirements first. Slash command integration is a trigger to an external micro service that: is listening to certain type of request generates response into a pre-defined Slack channel Also, this type of integration requires sending triggers…

Git Simplified – Undo changes and alter history

Post Written by
Marko Marjanović
Last modified on July 1st, 2020 at 2:40 pm

Reading time: 4 minutes

In this series of articles, we are going to learn the basics of the most popular versioning system today – Git. We already covered some basic commands and interacting via the Command Line Interface (CLI). In this part, we are going to use the most common techniques to undo changes and alter history. Git Message When committing changes, it is…

git simplified – part 1

Post Written by
Marko Marjanović
Last modified on July 1st, 2020 at 2:39 pm

Reading time: 5 minutes

Doing any coding without some kind of versioning control system ( VCS ) is nearly impossible today. Thanks to his creator, Linus Torvalds, we have a great distributed system that is pretty easy to start with, however very hard to master. Think of GIT as a tool that you will be constantly learning as you…

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