Articles tagged with #Linux




Top 10 usernames used in SSH brute force

As a follow up to yesterday's post I thought it would be interesting to know statistics of the usernames used in those brute force probes. Find below awk/sed script to get usernames for failed ssh login attempts from OpenSSH daemon and sort it for statistics. Also I attach the …



SSH brute force is on the rise, awk script to count failed SSH attempts

SSH brute forcing is still in high demand. I have , for my own testing and pleasure, virtual servers scattered around the world. All of them being of the Linux/BSD family I manage by SSH. Also I have on purpose no static IP at home for various reasons (saving me …



Alert on change of SOA in domain

This comes from unpleasant experience of mine. One of my clients’ domain records (MX for the case involved) was mistakenly changed. While it was a human error and trying to fix humans is rolling the rock of Sisyphus,damage would be much lesser had I known about the change immediately …



SSH login alert by mail Linux or Unix based systems

You can get mail lerts on SSH login to any Linux server using the script below. This script sends mail to predefined email address each time someone successfully logs in by SSH to the machine. I take advantage here of the built-in feature of the OpenSSH daemon – if you create …



Ping – setting don't fragment bit in Linux/Windows/FreeBSD/Solaris/Cisco/Juniper

Linux Windows FreeBSD Solaris CISCO routers (IOS) Juniper routers (JunOS) Ping. Many times while debugging network problems of various kinds you need to send some packets of desirable size and don’t fragment bit being set. I list below how to do it for the different equipment/OSes. Let’s …



Clear ARP table in Checkpoint

Update 2022: On modern Check Point systems you don't have to run the script below (which still works) as they come with up-to-date iproute2 network tools. So, to clear all dynamic ARP entries learned on a specific interface, use ip neighbor flush dev interface-name. Yesterday my colleague asked how to …



Autologin Expect scripts for telnet/ssh

Tired of typing over and over your username/password when using telnet/ssh ? Here are Expect https://core.tcl-lang.org/expect/index scripts to autologin by Telnet and ssh. Note: Yes, it is not secure to keep you username/password saved somewhere, so know what you do . In my opinion …



find tool patterns

These are few Linux find patterns I find useful in a daily work. The ones below were of great help when I had to clean Esafe that had more than 100,000 files in the spool ! So usual shell wild-card expansion didn't work (try to do ls in a folder …