OffSec Live: PEN-200

author: Nathan Acks
date: 2022-06-24

While I don’t think I’m quite ready yet to take a crack at the OSCP, Offensive Security’s free streaming classes (“OffSec Live”) seem like too good of a deal to pass up. I wasn’t able to catch the first because I was traveling, but I’ll be watching (and taking notes on) as many other sections as I can moving forward.

Terminal Best Practices

(I hopped on a few minutes late, unfortunately…)

File Descriptors

STDIN = 0
STDOUT = 1
STDERR = 2

I always forget that redirects work both ways:

# Redirect dmesg to an external file.
#
dmesg > boot.log

# Push boot.log into cat, and output with line numbers.
#
cat -n < boot.log

This, incidentally, makes the “heredoc” syntax a little more explicable - it’s basically “appending” text to the < redirect.

# "Heredoc", which I always forget about.
#
cat -n << EOF
Line A
Line B
Line C
EOF

# Also, redirect "heredoc" into a file.
#
cat << EOF > file.txt
Line A
Line B
Line C
EOF

Handy shortcut to clear the current terminal screen: CTRL+K.

CTRL+SHIFT+D will (horizontally) split the default terminal in Kali Linux; CTRL+SHIFT+R will split the default terminal vertically. Use CTRL+SHIFT+E to close a pane. That said, the separation between the created panes is much less clear than with Tmux.

Handy command: watch will periodically run a program (specify the interval with -n) and display the output in the terminal.

The extended regexp function with grep (-E) does not require the use of parentheses if you’re looking for a single “or” (for example, grep -E "kali|root" /etc/passwd).

Another trick: cut supports negative numbers to count fields from the right, rather than the left.