ssh tunnel into server behind NAT firewall

local_client:LPORT <—–> GPORT:guser@gateway_server <—-> RPORT:ruser@remote_server

Create the ssh tunnel:

ssh -f guser@gateway_server -L localhost:LPORT:remote_server:RPORT -N

Options: -f: go into background, -N: do not open a shell

Use the tunnel:

ssh -p LPORT ruser@localhost

scp, X forwarding, also works!

My (current) Picard naming scheme

This is my MusicBrainz Picard file naming scheme.
See this page for details.

$if($eq(%compilation%,1),

$noop(Various Artist Albums)

$if2(%albumartist%,%artist%)/

$left($if2(%originaldate%,%date%),4) %album%/

$if($gt(%totaldiscs%,1),

$noop(Various Artist Albums multiple discs)

CD %discnumber%$if(%discsubtitle%,: %discsubtitle%,)/,)

$num(%tracknumber%,2). %artist% - %title%,

$noop(Single Artist)

$firstalphachar($if2(%albumartistsort%,%artistsort%,%albumartist%,%artist%))/

$if2(%albumartist%,%artist%)/

$if(%album%,

$noop(It's An Album)

$if($eq($or(%originaldate%,%date%),1),

$left($if2(%originaldate%,%originalyear%,%date%,%year%),4) %album%/,%album%)/

$noop(Album Tracks multiple discs)

$if($gt(%totaldiscs%,1),

CD %discnumber%$if(%discsubtitle%,: %discsubtitle%,)/

$noop(Album Tracks single discs))

$num(%tracknumber%,2). %title%,

$noop(Non-Album Tracks)

%title%)

)

 

My car hi-fi makes a mess with with multi-disc albums because it doesn’t recognize discnumber tags. This script changes track numbers XX to include the disc numbers Y. The result is a 3 digit track number YXX:

$if($gt(%totaldiscs%,1),$set(tracknumber,%discnumber%$num(%tracknumber%,2)))

How to (partially) copy a corrupted file skipping bad blocks

dd if=OriginalCorruptedFile of=TargetFile bs=4k conv=noerror,sync

How to reduce the size of a PDF file

Using ghostscript:

 gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf input.pdf

To reduce it even more change -dPDFSETTINGS=/ebook to -dPDFSETTINGS=/screen.

Recover GRUB bootloader

If GRUB gets wiped by other operating system or is installed in the wrong disk, do this:

-> Boot from a live Debian USB

-> Start a console/terminal.

-> Find the disk where you want to install GRUB (sdX):

# lsblk -f

-> Create a mountpoint (/ospart) where you are going to mount your system partitition (sdXY)

# mkdir /ospart
# mount /dev/sdXY /ospart

-> Change root to the system partition (/ospart)

# for i in /sys /proc /dev; do mount --bind $i /target$i; done
# chroot /ospart /bin/bash

-> (Re)Install GRUB on your desired disk (sdX)
# grub-install /dev/sdX
# update-grub


> Reboot!

Colored prompts in bash

To get colored prompts in bash shells, all we have to do is to change the PS1 line in each user’s .basrc file:
nano ~$USER/.bashrc

If necessary uncomment the line:
force_color_prompt=yes

I have a green prompt for the main user:
PS1='${debian_chroot:+($debian_chroot)}\[33[01;32m\]\u@\h\[33[00m\]:\[33[01;34m\]\w\[33[00m\]\$ '
which is the default if you enable color prompts.

a red one for root:
PS1='${debian_chroot:+($debian_chroot)}\[33[01;31m\]\u@\h\[33[00m\]:\[33[01;34m\]\w\[33[00m\]\$ '

and a purple one for my NAS:
PS1='\[33[01;35m\]\h\[33[00m\]:\w\$ '

 

Convert audio tracks between PAL and NTSC

Audacity’s change tempo is the right tool.

And the % values to input are:

PAL -> NTSC: 25 / (24000/1001) = 1001/960 = 1.04270833… ( + 4.270833…%)
NTSC -> PAL: (24000/1001) / 25 = 960/1001 = 0.959040959… ( – 4.09590…%)

Dyn.com weekly login script

replace username and password accordingly.

/etc/cron.weekly/dynlogin:

#!/bin/bash
USER=username
PASS=password
rm cookie-dyn-com
sleep 1
MULTIFORM=$(curl -k -A “Mozilla/5.0 (X11; Linux i686; rv:10.0.7) Gecko/20100101 Firefox/10.0.7 Iceweasel/10.0.7” -e “https://account.dyn.com/entrance/&#8221; -b cookie-dyn-com -c cookie-dyn-com “https://account.dyn.com/entrance/&#8221; | grep -m1 multiform | tr ‘=’ ‘\n’ | tail -1 | cut -d “‘” -f 2)
sleep 1
curl -k -A “Mozilla/5.0 (X11; Linux i686; rv:10.0.7) Gecko/20100101 Firefox/10.0.7 Iceweasel/10.0.7” -e “https://account.dyn.com/entrance/&#8221; -b cookie-dyn-com -c cookie-dyn-com -d “username=$USER&password=$PASS&iov_id&multiform=$MULTIFORM” “https://account.dyn.com/entrance/&#8221;

Dyndns ddclient (Readynas addon) configuration file

replace emailaddress, username, password, servername1, servername2, servername3 accordingly.
/c/webroot/ddclient/ddclient.conf:

daemon=600
pid=/var/run/ddclient.pid
cache=/ramfs/ddclient.cache
#do not activate ssl
ssl=yes
syslog=yes
mail-failure=emailaddress # Mail failed updates to user
use=web, web=checkip.dyndns.com/, web-skip=’IP Address’
#uncomment the line bellow
#enlever le # sur les lignes suivantes :
login=username
password=password
protocol=dyndns2
server=servername1,servername2,servername3
#wildcard=YES

Use an SOCKS5 proxy through an SSH tunnel

From calomel.org

ssh and direct connect (SOCKS5) :

The following line will start the ssh client and connect to username@remote_machine.com.

Port 8080 on localhost (127.0.0.1) will listen for requests and send them to the remote machine.

The remote machine will then send the packets out as if they originated from itself.
ssh -C2qTnN -D 8080 username@remote_machine.com
Leave it running. And just configure the SOCKS5 proxy in the browser (localhost:8080)