Commands by ryanchapman (5)

  • Encrypt/decrypt a string from the command line

    Need to encrypt something from the command line? I've used this before to encrypt passwords with a master password that was shared amongst a team. To decrypt: ~$ echo -n 'jA0EAwMCPdknsznAww5gySL1/quqhXg6QgQkIz5abzGP5EZgTbXCFU+y6dP8ySWovytc' | base64 --decode | gpg --decrypt gpg: CAST5 encrypted data Enter passphrase: secret gpg: encrypted with 1 passphrase HelloWorld! Show Sample Output


    0
    echo 'HelloWorld!' | gpg --symmetric | base64
    ryanchapman · 2013-07-06 08:30:35 1
  • Backup a directory structure

    Copies a directory structure from /home/ to /backups/home (notice that the destination does not have a trailing slash)


    1
    BEGIN=`date`; rsync -avxW /home/ /backups/home ; echo "Begin time: $BEGIN" ; echo "End time..: `date`"
    ryanchapman · 2013-07-06 08:24:45 0
  • strace a program

    How to figure out what a program is doing. -tt detailed timestamps -f also strace any child processes -v be very verbose, even with common structures -o write output to file -s N capture up to N characters of strings, rather than abbreviating with ...


    0
    strace -ttvfo /tmp/logfile -s 1024 program
    ryanchapman · 2013-07-06 08:19:29 0
  • I/O activity on a machine

    Shows a constantly updating display of disk IO activity. Two sections are in the output. The first is the IO activity since the machine was booted, the second section is the IO activity in the last second Show Sample Output


    0
    watch -n 1 'iostat -xmd 1 2'
    ryanchapman · 2013-07-06 08:07:32 0
  • Decrypt SSL

    If on a web server (with access to the ssl key), decrypt SSL off the wire


    0
    openssl pkcs8 -in /etc/pki/tls/web.key -out /root/wc.key -nocrypt && tshark -o "ssl.desegment_ssl_records:TRUE" -o "ssl.desegment_ssl_application_data:TRUE" -o "ssl.keys_list:,443,http,/root/wc.key" -o "ssl.debug_file:rsa.log" -R "(tcp.port eq 443)"
    ryanchapman · 2013-07-06 08:01:36 5

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Determine if a port is open with bash
For times when netcat isn't available. Will throw a Connection refused message if a port is closed. Scriptable: $ (: /dev/null && echo "OPEN" || echo "CLOSED"

Sniff ONLY POP3 authentication by intercepting the USER command
dsniff is general purpose password sniffer, it handles *lots* of different protocols, but it also handles tcp-style expressions for limiting analyzed traffic - so I can limit it to work on pop3 only.

Creating ISO Images from CDs/DVDs
create an iso from your cd/dvd-rom device . You need to umount /dev/cdrom before using the cli

flip faster and more precisely through commands saved in history
flip shell history with PG UP/PG DOWN like with arrows. just type ss and PG UP and see all ssh commands, type ls and PG DOWN - see all ls commands. need to uncomment two options in /etc/inputrc: "\e[5~": history-search-backward "\e[6~": history-search-forward hack found: http://broddlit.wordpress.com/2008/04/12/making-the-bash-history-a-better-place/

Reclaim standard in from the tty for a script that is in a pipeline
This will grab the controlling tty regardless of what STDOUT and STDERR are doing.

from within vi, pipe a chunk of lines to a command line and replace the chunk with the result
The vi key sequence !}command will send the file contents from the cursor to the next blank line as STDOUT to the command specified and replace that sequence of file lines with the output of the command. For example: sorting a block of data - !}sort The sequence !{command will do the same but "upwards" (from the current position towards the start of the file.

Listing package man page, services, config files and related rpm of a file, in one alias
Many times I give the same commands in loop to find informations about a file. I use this as an alias to summarize that informations in a single command. Now with variables! :D

Increase mplayer maximum volume
use '0' and '9' to increase/decrease volume. this is useful on laptops with low speaker volume.

Backup files older than 1 day on /home/dir, gzip them, moving old file to a dated file.
Useful for backing up old files, custom logs, etc. via a cronjob.

rotate a one page pdf to 90 Degrees Clockwise
This can be taken from the pdftk docs http://www.pdflabs.com/docs/pdftk-man-page/ http://www.pdflabs.com/docs/pdftk-cli-examples/ , but the command examples are not simple.

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