This is a description of an uncomplicated setup for an encrypted volume and portable applications for a Windows laptop consisting of a USB3 storage device, VeraCrypt OSS OTFE, a hardware password wallet, and portableapps.com software.
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Commands & Shells »
Tmux Bootstrap Configuration
Just a list of commands to quickly configure tmux with some of the best (i.e. my favorite) plugins and options. Feel free to disagree – you may be right – but I don’t think so. Read the full story »
Find Large Files
Every time a filesystem is running out of space and I need to find something to delete, I end up googling the syntax for the find command to make sure it stays off NFS and …
Show Logged In Users During a Time Window
Let’s say you want to see who was logged in on the server during last weekend. This includes users who, say, logged in on Thursday and haven’t logged out until Saturday afternoon.
Extracting Email Addresses from TCP Streams
Here’s a quick example of using tshark to extract email addresses from TCP streams. Let’s say some application on your server is sending emails and you want to find out who is receiving those emails.
Export WP Posts and Sync to Sharepoint
Long story short: old wiki is overloaded and broken; new wiki is not a wiki but SharePoint – a glorified file server; people are forced to improvise and put documentation on a WP wiki; bosses …
Useful MySQL One-Liners
I am by no means an expert SQL programmer. Having said that, I’ve been using MySQL for a very long time. This is a collection of simple but useful SQL queries and MySQL configuration options. …
Plotting Log Data
While I am on the subject of selecting time ranges from logs, a practical application presented itself. A lonely server in a far-away land with a habit of running out of memory could only be …
Croncal – the Cron Calendar
The croncal is a clever Perl script that reads entries in your crontab and outputs a schedule, showing the time when cron jobs will run.
Install and Configure Etckeeper
Etckeeper is a handy tool that uses git to keep track of changes to anything in /etc (or any other folder you choose). It’s very simple to use and can help you quickly identify and undo stupid …
Using IPTables to Allow Access to Private Networks
Below is a quick example of how to use iptables to allow port access for all types of private networks. In this case we’re allowing access to ports 10000 and 20000, commonly used by webmin and usermin.
Get a List of all ESX Hosts in a Datacenter
Another simple one-liner to get a list of hostnames of all ESX servers in the vCenter. This can be useful for a number of things, specifically as input for other PowerCLI scripts.
Use PowerCLI to Change NIC Type
This is a quick PowerCLI script that reads from a list of VM names and for each VM with network adapter type “E1000” changes it to “Vmxnet3”. Nothing fancy, no reboot is needed. MAC should …
Pushing SSH Keys
This is just a quick note for me on pushing SSH keys using sshpass and xargs. The ~/hosts.txt file contains a list of remote hosts, one per line. And the ~/.passwd.txt contains your password. Make sure to chmod 400 …
Configure and Run esxcli on Red Hat
The esxcli utility is used to interface with the vSphere and ESX hosts. It is a useful tool for getting to some basic VMWare functionality from Unix shell. It is also a pre-requisite for some of …
Wget Examples
This is a follow-up to my previous wget notes (1, 2, 3, 4). From time to time I find myself googling wget syntax even though I think I’ve used every option of this excellent utility over the …
Samba Flexible Character Mapping
This is probably old news to most of you, but I just found out: Samba v 3.5+ has a new option for flexible mapping of filename characters. Unix filenames allow certain characters that Windows filename …
Install Webmin on CentOS and Redhat
Just a quick short-hand to installing Webmin on CentOS/RHEL. The latest Webmin version comes with a cool new interface theme. You should check it out.
Managing VMs with PowerCLI
Below is a collection of useful Power-CLI one-liners (or thereabouts) that can speed up your script-writing efforts. As everything Windows, things change often and for no obvious reason, so expect to see type is deprecated and …
Sun T-Series ILOM and Solaris 11 Network Configuration
Just some quick notes on setting up Oracle Sun T-series server ILOM and network aggregation with LACP. I don’t get to do this very often, so every time it’s a struggle to remember, with much …
Monitoring DNS Queries
Recently I’ve been decommissioning old DNS servers and those things are notoriously hard to get rid of. The problem was that the IP addresses could not be preserved. I needed to track down every incoming …
Google Search Tips
Google has some advanced search features that few people use, which is a shame. Here are some of them, by Karl Hindle. I am sure there are a few more, but these are the more …
Verify Network Port Access
There are several tools you can use to verify access to a remote network port: nc, tcping, telnet. Unfortunately, nc from the netcat package has been replaced by the one from nmap, which lacks the -z option, making …
Rsync Time Backup
This is a simple wrapper for the awesome rsync-time-backup script by Laurent Cozic. Through clever use of hard links rsync-time-backup greatly speeds up incremental backups and saves disk space.
Commands & Shells »
Obfuscating Passwords in Shell Scripts
At the risk of repeating myself, I must say that this article is about obfuscating passwords – rendering obscure, unclear, or unintelligible – not hiding them. This can still be useful.
Whiptail and Dialog Snippets
Whiptail is a newt-based utility allowing to build pseudo-graphical dialog boxes from shell scripts. Dialog uses ncurses and is similar to whiptail but has more options and, consequently, a bit harder to use. I find both useful …
Applications »
SystemD: Back To The Future
A creature in its death throes, Sun Microsystems gave birth to Solaris SMF – the product of a disturbing union between Unix System V and the Microsoft Windows Registry. Shortly thereafter the proud father died, …
Sample Salt Proxy Configuration for vCenter/ESX
The Salt proxy agent is a relatively new feature of Salt allowing to control networked devices where salt-minion cannot be installed directly. The official Salt documentation on the subject is outdated and full of syntax errors. It’s actually …
Data »
Detect SSL Certificate Injection
When the SSL Digital Certificate is intercepted and replaced by a device between your browser and the Web site, we call it certificate injection. This method is more commonly used not by hackers, but by …
SSL For Self-Hosted WordPress
Just some notes for setting up SSL with your self-hosted WordPress installation. Just got around to doing this the other day. Yeah, I know, about time…
Monitoring »
CLI System Monitoring Tools
The multitude of sophisticated centralized monitoring tools available these days excel at one thing: telling you what happened while you’ve been sleeping. But what if you’re awake and need to know what’s going on right …
Watching VSFTP
I have an FTPS server running VSFTP and below is collection of commands useful for monitoring activity and analyzing the logs.
Networking »
Detect SSL Certificate Injection
When the SSL Digital Certificate is intercepted and replaced by a device between your browser and the Web site, we call it certificate injection. This method is more commonly used not by hackers, but by …
Occupy Subnet
The script below (tested on RHEL 7) will use arp-scan to identify unused IPs on your subnet and configure virtual interfaces attached to your primary NIC to take over every available IP.
Editor
Igor
Sr. Unix SysAdmin with twenty years experience supporting Solaris, HP-UX, AIX, IRIX, and Linux servers in a large distributed environment.
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