Friday, July 31, 2015

Book Review: Lead Guitar Harvey Vinson

I'm learning Lead guitar from Harvey Vinson's book.  I came across this book in a used bookstore, and it came with flexible record.  Apparently, this is was how music was shipped in the Analogue age.  The technology involved is quite impressive: you can stamp these flexible records out quite cheaply, they are flexible and light.  And you can play it without electricity, if you have a hand-cranked turntable.

So I was talking about this book with my friends, and one of them offered to transcode the record into a format for the digital age.  Mr. DM took the book from me, and returned me three files containing both sides of the record. Side One has a short tuning prelude, and then a rhythm backing track for standard blues in G.  Side Two has tuning, a triplet blues backing track in G, and a track for turnaround in G.

The choice of G is interesting: I much prefer the key of A.  While you are learning, it doesn't matter.

The book goes through the pentatonic scale, the blues variation, and shows you how to build lead for a standard 12 bar blues song.  With the backing track, you can practice and make your own song.  This format works very well: you are learning something basic, and then the book gives you enough understanding to start making your own music.  To a student, this is the most fulfilling part of learning: creating something new.  Many guitar books start the student out on basic tunes.  For a while this is sufficient, but many students tire out of playing dull tunes.  It is exciting to be able to make your own music, to record it, and share it with friends.  This book gives you enough insight that you can start learning the basic of 12 bar blues, and gives you enough starting points to develop your own solos, and your own riffs.

Here are the audio files, in case you have this obscure book, and are stuck with a record that you cannot play any more.  You can download these files and play them locally as backing tracks while you are using the book.  You can also add the audio track to your existing audio project (Logic Pro or Audacity) and record your lead guitar in a separate track.

Side One
Side Two Triplet Blues in G
Side Two Turnaround in G 

 Courtesy: DM for doing an amazing job at converting the record.

Thursday, July 30, 2015

Limiting the rate of ssh connections

The internet is a wild place.  I have an SSH server that is open.  The machine is locked down with very few accounts, all with long passwords, but that doesn't deter attackers from trying to get into the machine.  Most attacks are against the root account, which is futile since the root password is hopelessly long.  And it only accepts public key authentication on that account.

Here is a script I use to limit the number of ssh connections.  As a sample, I show how to rate-limit connections to two ports (222 and 2222) down to one connection in a 60 second window.  Most automated attack scripts back off very rapidly when they notice that they don't get through.  So this easy remedy is enough to thwart a majority of the bot-infested machines.


# Clear all chains
/sbin/iptables -F
/sbin/iptables -L -v -n

# Create a new chain to log and then to drop
/sbin/iptables -N LOGDROP
/sbin/iptables -A LOGDROP -j LOG
/sbin/iptables -A LOGDROP -j DROP

# The external ports 222 and 2222 need to be rate limited.
iptables -I INPUT -p tcp --dport 222 -i eth0 -m state --state NEW -m recent --set --name FIRST
iptables -I INPUT -p tcp --dport 2222 -i eth0 -m state --state NEW -m recent --set --name SECOND

# One connection in a 60 second window.
iptables -I INPUT -p tcp --dport 222 -i eth0 -m state --state NEW -m recent  --update  --name FIRST --seconds 60 --hitcount 1 -j LOGDR
iptables -I INPUT -p tcp --dport 2222 -i eth0 -m state --state NEW -m recent  --update  --name SECOND --seconds 60 --hitcount 1 -j LOG