Beware: certain Amazon EC2 AMI’s terminate at shutdown

I toyed with Amazon EC2 last year by migrating my web server there. After issuing shutdown -P in Ubuntu last week, my instance disappeared from the list in the AWS dashboard. I seeked help and found out that some AMI’s are set to terminate at shutdown. Unfortunately, the AMI I used was one of them. Files and settings are not recoverable after an instance is terminated. Luckily, I transferred most of my critical information out prior to the shutdown; I’m only missing one file. Note to self: for all future instances, the shutdown behavior to stop (as opposed to terminate) could be modified per these instructions. First, create and download the X.509 certificate and private key. To access the EC2 api, do the following on your computer:

sudo apt-get install ec2-api-tools ec2-ami-tools ##ec2-init

Then, do the following to find out what behavior is currently set on your instance:

ec2-describe-instance-attribute i-AMAZON-INSTANCE-ID --instance-initiated-shutdown-behavior -K /path/to/x509-key.pem -C /path/to/x509-cert.pem 

If the value is not stop, then do

ec2-modify-instance-attribute i-AMAZON-INSTANCE-ID -K /path/to/x509-key.pem -C /path/to/x509-cert.pem --instance-initiated-shutdown-behavior stop

Symlinks in samba and sshfs

When setting up sshfs mounts and Linux samba servers, one can make it so that symbolic links are followed (so they aren’t broken). For sshfs, add the follow_symlinks option. In /etc/fstab/, the entry would look something like

sshfs#USERNAME@SERVERNAME: /mnt/acer fuse fsname=sshfs#USERNAME@SERVERNAME:,comment=sshfs,noauto,users,exec,uid=1000,gid=1000,allow_other,reconnect,transform_symlinks,follow_symlinks,BatchMode=yes 0 0

For samba, add the following to either the [global] options or the individual location in /etc/samba/smb.conf:

follow symlinks = yes
wide symlinks = yes
unix extensions = no

Make sure samba is restarted and the sshfs mount point is re-mounted.

Startup applications in LXDE: caps lock as control

I just installed Linux Mint on my Asus T101MT. As with all my computers, I prefer to have the caps lock key as a control key. Of these methods, only the xkb command works. To have the key remapped every session, I followed these instructions and created the file ~/.config/autostart/nocaps.desktop:

[Desktop Entry]
Encoding=UTF-8
Name=nocaps
Comment=Remap caps lock as control.
Exec=setxkbmap -option ctrl:nocaps
Terminal=true

Cryptography

This site lists 52 things that people should know about cryptography, if you want to get into the cryptography world. I was also recommended Bruce Schneier’s book, Applied Cryptography: Protocols, Algorthms, and Source Code in C.