Two New Power User Hacks

Tip #1. I learned two new hacks.  – one to regain control and inspect an SSH Session.  Thanks to ServerFault. https://serverfault.com/questions/283129/why-do-consoles-sometimes-hang-forever-when-ssh-connection-breaks ~. – terminate connection (and any multiplexed sessions) ~B – send a BREAK to the remote system ~C – open a command line ~R – request rekey ~V/v – decrease/increase verbosity (LogLevel) ~^Z – […]

Cups and Raspberry Pi – How to setup your print server

Print Server is one of those things that makes life easier.  I hooked up my Raspberry Pi and a Docker image in order to have a CUPS server and the Bonjour configuration. Login to the Raspberry Pi and switch to root (sudo -s or sudo su –) Check lsusb to see if you can see […]

FirewallD

Fast commands for enabling firewalld on RHEL7 and CENTOS7. I had to enable these for a secondary control on a project I am on. Check the Status of the Firewall on Each Machine and confirm firewalld is started. systemctl status firewalld ● firewalld.service – firewalld – dynamic firewall daemon    Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor […]

VirtualBox Additions missing

If you see Kernel Headers not found for target kernel level when installing the VBoxLinuxAdditions.run “Please install them and execute”. This issue was found on centos. You’ll see the commands below: yum install “kernel-devel-uname-r ==$(uname -r)” References https://unix.stackexchange.com/questions/232147/your-kernel-headers-for-kernel-3-10-0-229-el7-x86-64-cannot-be-found

Fix DB_RUNRECOVERY

Ran into this issue today, and a fast fix. [root@xyz ~]# yummut_tas:172, pid: 16043, flag: 19error: db5 error(-30973) from dbenv->failchk: BDB0087 DB_RUNRECOVERY: Fatal error, run database recoveryerror: cannot open Packages index using db5 – (-30973)error: cannot open Packages database in /var/lib/rpmCRITICAL:yum.main: Error: rpmdb open failed[root@xyz ~]# rpm –rebuilddb [root@xyz~]# rpm –rebuilddb[root@xyz ~]# yumLoaded plugins: search-disabled-reposYou […]

Kerberos and Java

I have worked on a kerberos smoke test for my team. I learned a few tips in the process. The useTicketCache is a preferred use in case the java process dies while the KDC is down. HBase Canary Testing runs on a kerberos enabled cluster using hbase canaryhttp://hbase.apache.org/book.html#trouble.client If you are port forwarding over SSH, […]

Forwarding DGram in node.js

For a project I am working on I needed to rewrite a DGram port. I moved the ports around and found a few quick tests. Testing with NC my-machine:~$ echo -n “data-message” | nc -v -4u -w1 localhost 88found 0 associationsfound 1 connections:1: flags=82<CONNECTED,PREFERRED> outif (null) src 127.0.0.1 port 53862 dst 127.0.0.1 port 88 rank […]

COS and Hadoop FS issue

I ran into this issue with Python and IBM Cloud Object Storage. I applied a quick fix: pyspark –packages com.ibm.stocator:stocator:1.0.24 https://github.com/ibm-watson-data-lab/ibmos2spark/tree/master/python https://github.com/ibm-watson-data-lab/ibmos2spark/tree/master/pythonhttps://blog.sicara.com/get-started-pyspark-jupyter-guide-tutorial-ae2fe84f594f https://stackoverflow.com/questions/46011671/no-filesystem-for-scheme-cos