Commands by bsb (1)

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print contents of file from line 1 until we match regex
Start printing the contents of filename to stdout, until a matching line to regex is found, then stop.

List top 20 IP from which TCP connection is in SYN_RECV state
List top 20 IP from which TCP connection is in SYN_RECV state. Useful on web servers to detect a syn flood attack. Replace SYN_ with ESTA to find established connections

Remind yourself to leave in 15 minutes
If you spend most of your time in front of the terminal, leave is a useful reminder. Leave can have absolute form: leave 1555 reminds you to leave at 3:55PM

complete extraction of a debian-package
extracts the debian-package $debfile to $extractdir, including all packaging-information. to repack the package, just type: $dpkg-deb -b $extractdir

Detect illegal access to kernel space, potentially useful for Meltdown detection
Based on capsule8 agent examples, not rigorously tested

Create a directory and cd into it
This creates a bash function `take` that you can call with the name of the directory as the first parameter. Add the function to ~/.bashrc to have it available anytime.

Find usb device
I often use it to find recently added ou removed device, or using find in /dev, or anything similar. Just run the command, plug the device, and wait to see him and only him

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

SMTP Analysis
This works just as well for SMTP. You could run this on your mail server to watch e-mail senders and recipients: tcpdump -l -s0 -w - tcp dst port 25 | strings | grep -i 'MAIL FROM\|RCPT TO'

find duplicate messages in a Maildir
# find assumes email files start with a number 1-9 # sed joins the lines starting with " " to the previous line # gawk print the received and from lines # sort according to the second field (received+from) # uniq print the duplicated filename # a message is viewed as duplicate if it is received at the same time as another message, and from the same person. The command was intended to be run under cron. If run in a terminal, mutt can be used: mutt -e "push otD~=xq" -f $folder


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