Author Archives: jeffrin

appending file using “paste” command hack

$cat a.txt hello $cat b.txt killo $ls 1 a.txt b.txt l.txt trueangle u.txt $cat u.txt UPPERCASE $cat l.txt uppercase $cat a.txt >> b.txt >> l.txt >> u.txt $cat u.txt UPPERCASE hello $cat a.txt hello $cat 1 a.txt b.txt l.txt trueangle/ u.txt $cat l.txt uppercase $cat a.txt hello $cat a.txt >> b.txt $cat b.txt killo hello …

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sample hack session with sort command

$sort -t: -k3 –debug /etc/passwd sort: using ‘en_US.UTF-8’ sorting rules root:x:0:0:root:/root:/bin/bash ________________________ _______________________________ jeffrin:x:1000:1000:Jeffrin Jose T,,,:/home/jeffrin:/bin/bash ___________________________________________________ _____________________________________________________________ uuidd:x:100:101::/run/uuidd:/bin/false ______________________________ ______________________________________ uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin ____________________________________________ ___________________________________________________ Debian-exim:x:101:103::/var/spool/exim4:/bin/false ____________________________________ __________________________________________________ statd:x:102:65534::/var/lib/nfs:/bin/false __________________________________ __________________________________________ sshd:x:103:65534::/var/run/sshd:/usr/sbin/nologin __________________________________________ _________________________________________________ messagebus:x:104:106::/var/run/dbus:/bin/false _________________________________ ______________________________________________ colord:x:105:109:colord colour management daemon,,,:/var/lib/colord:/bin/false _____________________________________________________________________ ______________________________________________________________________________ usbmux:x:106:46:usbmux daemon,,,:/home/usbmux:/bin/false _______________________________________________ ________________________________________________________ avahi:x:107:113:Avahi mDNS daemon,,,:/var/run/avahi-daemon:/bin/false _____________________________________________________________ _____________________________________________________________________ pulse:x:108:114:PulseAudio daemon,,,:/var/run/pulse:/bin/false ______________________________________________________ ______________________________________________________________ …

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encryption related algorithms that are built into a typical Linux Kernel

ABOUT Cryptography Cryptography or cryptology (from Ancient Greek: κρυπτός, translit. kryptós “hidden, secret”; and γράφειν graphein, “to write”, or -λογία -logia, “study”, respectively[1]) is the practice and study of techniques for secure communication in the presence of third parties called adversaries.[2] More generally, cryptography is about constructing and analyzing protocols that prevent third parties or …

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sample session related to “command expansion” in Bash shell

$a=`time` real 0m0.000s user 0m0.000s sys 0m0.000s $a bash: a: command not found $a=`ls` $a bash: a: command not found $echo a a $echo $a a.txt b.txt trueangle $echo `a` bash: a: command not found $a=`ls` $b=time $echo $b time $b=`time` real 0m0.000s user 0m0.000s sys 0m0.000s $echo $b $b=`time` real 0m0.000s user 0m0.000s sys …

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using the dir() Built-in function in Python programming

>>> import struct >>> dir() # show the names in the module namespace [‘__builtins__’, ‘__doc__’, ‘__name__’, ‘struct’] >>> dir(struct) # show the names in the struct module [‘Struct’, ‘__builtins__’, ‘__doc__’, ‘__file__’, ‘__name__’, ‘__package__’, ‘_clearcache’, ‘calcsize’, ‘error’, ‘pack’, ‘pack_into’, ‘unpack’, ‘unpack_from’] >>> class Shape(object): def __dir__(self): return [‘area’, ‘perimeter’, ‘location’] >>> s = Shape() >>> dir(s) …

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sample session using “variable expansion” with Bash shell

$com=world $echo com com $echo $com world $x=hello $echo ${x}{com} hello{com} $echo ${x}${com} helloworld $echo $x$com helloworld $echo ${x}world helloworld $echo ${x} world hello world $echo $x world hello world $echo $xcom $echo $x com hello com $echo $x $com hello world $echo $x$com helloworld $echo $xcom $echo ${x}com hellocom $ $your_id=${USER}-on-${HOSTNAME} $echo “$your_id” jeffrin-on-debian …

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