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It takes over 5 seconds to scan a single port on a single host using nmap
$ time (nmap -p 80 192.168.1.1 &> /dev/null)
real 0m5.109s
user 0m0.102s
sys 0m0.004s
It took netcat about 2.5 minutes to scan port 80 on the class C
$ time (for NUM in {1..255} ; do nc -w 1 -z -v 192.168.1.${NUM} 80 ; done &> /dev/null)
real 2m28.651s
user 0m0.136s
sys 0m0.341s
Using parallel, I am able to scan port 80 on the entire class C in under 2 seconds
$ time (seq 1 255 | parallel -j255 'nc -w 1 -z -v 192.168.1.{} 80' &> /dev/null)
real 0m1.957s
user 0m0.457s
sys 0m0.994s
With zsh.
This function counts the opening and closing braces in a string. This is useful if you have eg long boolean expressions with many braces and you simply want to check if you didn't forget to close one.
As of March 7, 2012:
$ brew update - downloads upgraded formulas
$ brew upgrade [FORMULA...] - upgrades the specified formulas
$ brew outdated - lists outdated installations
Note updating all packages may take an excruciatingly long time. You might consider a discriminating approach: run `brew outdated` and select specific packages needing an upgrade.
For more information see homebrew's git repository: https://github.com/mxcl/homebrew
Convert DOS newlines (CR/LF) to Unix format using sed command
Converts any number of seconds into days, hours, minutes and seconds.
sec2dhms() {
declare -i SS="$1"
D=$(( SS / 86400 ))
H=$(( SS % 86400 / 3600 ))
M=$(( SS % 3600 / 60 ))
S=$(( SS % 60 ))
[ "$D" -gt 0 ] && echo -n "${D}:"
[ "$H" -gt 0 ] && printf "%02g:" "$H"
printf "%02g:%02g\n" "$M" "$S"
}
You might want to secure your AWS operations requiring to use a MFA token. But then to use API or tools, you need to pass credentials generated with a MFA token.
This commands asks you for the MFA code and retrieves these credentials using AWS Cli. To print the exports, you can use:
`awk '{ print "export AWS_ACCESS_KEY_ID=\"" $1 "\"\n" "export AWS_SECRET_ACCESS_KEY=\"" $2 "\"\n" "export AWS_SESSION_TOKEN=\"" $3 "\"" }'`
You must adapt the command line to include:
* $MFA_IDis ARN of the virtual MFA or serial number of the physical one
* TTL for the credentials