Tag: awk
Linux
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One-line batch file renamer
If you want to batch rename a bunch of files (say “foo*.jpg” to “bar*.jpg”), you might think you could just do “mv foo*.jpg bar*.jpg” in the Terminal. However, this doesn’t work right since the shell expands each argument before the execution occurs. However, there’s a cool way to accomplish the same result with a (more […]
Security
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Rule-based DoS attacks prevention shell script
Dette scriptet er ikke testet samt DoS bør hindres på kernel nivå! A simple rule-based DoS attack-prevention shell script. However, the proposed shell script is not a perfect tool for preventing DoS attacks, but a powerful tool for alleviating DoS attacks overheads of the Linux servers significantly.
Scripting
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Monitoring /var/log/secure for break-in attempts
date >> ssh-intruders.log ; cat /var/log/secure | grep -i “sshd.*authentication failure” | sort | awk ‘{FS=”rhost=”; print $2}’ | awk ‘{FS=”user=”; print $1}’ | grep “.*\..*\.” | grep -v “knownhost.com” | grep -v “knownhost2.com” | sort | uniq | while read i; do counter=`grep -i “$i” /var/log/secure | wc -l` ; echo “$counter attempts by […]
Linux
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Find duplicate usernames in /etc/passwd
# cat /etc/passwd | awk -F: ‘{print $1}’ | sort | uniq -c | grep -v 1 # cat /etc/shadow | awk -F: ‘{print $1}’ | sort | uniq -c | grep -v 1 # awk -F: ‘{ print $1, $5}’ /etc/passwd