Linux

crons and crontab

Time Scheduler Notation: Standard Minute Hour DayOfMonth Month DayOfWeek * = any value , = value list separator – = range of values / = step values (Increments) Non-Standard @yearly @annually @monthly @weekly @daily @hourly @reboot Examples Run a cron once every minute * * * * * /path/to/script */1 * * * * /path/to/script… read more »

Offending key for IP in /home/username/.ssh/known_hosts:NUMBER

This issue has haunted me for years and yet it is so easy to fix. Issue: Offending key for IP in /home/<USERNAME>/.ssh/known_hosts:<NUMBER> Matching host key in /home/<USERNAME>/.ssh/known_hosts:<ANOTHER_NUMBER> Description The problem lies in that there are 2 keys for the host you are trying to reach.  One key is old and one is good. Solution Edit… read more »

Apache Not Starting for unknown reasons

Seeing this? Job for apache2.service failed because the control process exited with error code. See “systemctl status apache2.service” and “journalctl -xe” for details. Followed by running both of the suggested commands only to learn nada darn thing?? Here’s a few things I’ve found. Check any new SSL Certs Make sure any self-signed certificates are made… read more »

Install LAMP on Ubuntu

Linux, Apache, MariaDB (or MySQL) and PHP These steps work with both Ubuntu 18.04 LTS and Ubuntu 20.04 LTS I’ve included steps for both MariaDB and MySQL. sudo apt update -y sudo apt upgrade -y sudo apt install apache2 -y # MariaDB sudo apt install mariadb-server -y # MySQL sudo apt install mysql-server -y sudo… read more »

SSH without a Password

1. Log into the source computer (the computer you will use to log into the destination).   2. Check if  you already have an SSH key generated.  This key identifies you as the user. ls ~/.ssh | grep id_rsa   If the above command returned results, do not create a new key and skip to… read more »

tcpdump

TCPDump Captures network traffic. Must be ran as root. Common Usage Capture SNMP traffic from a host in zentrap sudo tcpdump -i any -n udp and src host 10.10.10.10 Capture SNMP traffic from a host on the zentrap host sudo tcpdump -i any -n udp and src host 10.10.10.10 and port 162 Configuration Switch Name… read more »

Bash Loops

Examples of various looping scripts using bash Arrays and Counts Loop through an incremental count for INDEX in {0..5}; do echo $INDEXdone# one linerfor I in {0..5}; do echo $INDEX; done   For Loops Use these with variables! # Loops 5 timesSTART=0END=4for ((INDEX=$START; INDEX<=$END; INDEX++)) do echo $INDEXdone   Files Looping through items in a… read more »

How to connect to a Cisco Device using USB Console

This article was written using instructions for Ubuntu, but was actually tested on a Raspberry Pi. Cool, eh? https://www.youtube.com/watch?v=PRwHNd-u_cA Install minicom $ sudo apt-get install minicom Find the device $ dmesg | grep ttyUSB [ 5.494345] usb 1-1.2: Moschip 2 port adapter converter now attached to ttyUSB0 Note the device: In this case it is… read more »

Linux TOP command

1st Row – top top – 11:37:19 up 30 min, 3 users, load average: 0.02, 0.01, 0.06 current time (11:37:19) uptime of the machine (up 30 min) users sessions logged in (3 users) average load on the system (load average: 0.02, 0.01, 0.06) the 3 values refer to the last minute, five minutes and 15… read more »

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