$ls stderr.txt stderr.txt $ls stderr.txt | xargs ls stderr.txt $ls stderr.txt | xargs cat /home/jeffrin/quark/kernel/run_kernel.sh: line 10: ./main.native: No such file or directory $ls stderr.txt | xargs gzip $ls stderr.txt ls: cannot access 'stderr.txt': No such file or directory $ls stderr.txt.gz | xargs gunzip $ls stderr.txt stderr.txt $
Finding the number of processor units
ABOUT nproc
print the number of processing units available
TYPICAL COMMANDLINE SESSION
[bash]
$nproc
2
$nproc –ignore=1
1
$grep -c ^processor /proc/cpuinfo
2
$cat /proc/cpuinfo | awk ‘/^processor/{print $3=$3+1}’ | tail -1
2
$cat /proc/cpuinfo | awk ‘/^processor/{print $3}’
0
1
$lscpu | grep CPU
CPU op-mode(s): 32-bit, 64-bit
CPU(s): 2
On-line CPU(s) list: 0,1
CPU family: 21
CPU MHz: 2800.000
CPU max MHz: 3000.0000
CPU min MHz: 1400.0000
NUMA node0 CPU(s): 0,1
$lscpu | grep "CPU(s)"
CPU(s): 2
On-line CPU(s) list: 0,1
NUMA node0 CPU(s): 0,1
$lscpu | grep "CPU(s):"
CPU(s): 2
NUMA node0 CPU(s): 0,1
$lscpu | grep ^"CPU(s):"
CPU(s): 2
$lscpu | awk ‘FNR == 4 {print $2}’
2
$
[/bash]
LINKS
https://en.wikipedia.org/wiki/List_of_GNU_Core_Utilities_commands
http://man7.org/linux/man-pages/man1/nproc.1.html
https://blog.dbi-services.com/linux-how-to-monitor-the-nproc-limit-1/
finding the current state of a network cable
$sudo cat /sys/class/net/eth0/speed 100 $sudo cat /sys/class/net/eth0/ca carrier carrier_changes $sudo cat /sys/class/net/eth0/carrier 1 $sudo cat /sys/class/net/eth0/carrier_changes 2 $sudo cat /sys/class/net/eth0/operstate up $sudo ethtool eth0 Settings for eth0: Supported ports: [ TP MII ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Half 1000baseT/Full Supported pause frame use: No Supports auto-negotiation: Yes Advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Half 1000baseT/Full Advertised pause frame use: Symmetric Receive-only Advertised auto-negotiation: Yes Link partner advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full Link partner advertised pause frame use: Symmetric Receive-only Link partner advertised auto-negotiation: Yes Speed: 100Mb/s Duplex: Full Port: MII PHYAD: 0 Transceiver: internal Auto-negotiation: on Supports Wake-on: pumbg Wake-on: g Current message level: 0x00000033 (51) drv probe ifdown ifup Link detected: yes $ http://www.ostechnix.com/how-to-find-out-the-connected- state-of-a-network-cable-in-linux/
times command data structure tms exposed
times() stores the current process times in
the struct tms that buf points to.
The struct tms is as defined in <sys/times.h>:
struct tms {
clock_t tms_utime; /* user time */
clock_t tms_stime; /* system time */
clock_t tms_cutime; /* user time of children */
clock_t tms_cstime; /* system time of children */
};
httping with sending of username and password and flood ping
$httping -U www.beautifulwork.org No URL/host to ping given $httping -U http://www.beautifulwork.org No URL/host to ping given $httping http://www.beautifulwork.org PING www.beautifulwork.org:80 (/): connected to 89.36.208.169:80 (224 bytes), seq=0 time=455.10 ms connected to 89.36.208.169:80 (224 bytes), seq=1 time=458.34 ms connected to 89.36.208.169:80 (224 bytes), seq=2 time=447.45 ms ^CGot signal 2 --- http://www.beautifulwork.org/ ping statistics --- 4 connects, 3 ok, 0.00% failed, time 4418ms round-trip min/avg/max = 447.5/453.6/458.3 ms $httping -U anonymous http://www.beautifulwork.org $httping -U anonymous http://www.beautifulwork.org PING www.beautifulwork.org:80 (/): connected to 89.36.208.169:80 (224 bytes), seq=0 time=453.33 ms connected to 89.36.208.169:80 (224 bytes), seq=1 time=459.89 ms connected to 89.36.208.169:80 (224 bytes), seq=2 time=451.59 ms connected to 89.36.208.169:80 (224 bytes), seq=3 time=455.54 ms connected to 89.36.208.169:80 (224 bytes), seq=4 time=448.82 ms ^CGot signal 2 --- http://www.beautifulwork.org/ ping statistics --- 5 connects, 5 ok, 0.00% failed, time 6948ms round-trip min/avg/max = 448.8/453.8/459.9 ms $httping -U userfoo http://www.beautifulwork.org PING www.beautifulwork.org:80 (/): connected to 89.36.208.169:80 (224 bytes), seq=0 time=449.55 ms connected to 89.36.208.169:80 (224 bytes), seq=1 time=462.89 ms connected to 89.36.208.169:80 (224 bytes), seq=2 time=446.10 ms connected to 89.36.208.169:80 (224 bytes), seq=3 time=445.94 ms ^CGot signal 2 --- http://www.beautifulwork.org/ ping statistics --- 4 connects, 4 ok, 0.00% failed, time 5721ms round-trip min/avg/max = 445.9/451.1/462.9 ms $httping -U userfoo -P withfoo http://www.beautifulwork.org PING www.beautifulwork.org:80 (/): connected to 89.36.208.169:80 (224 bytes), seq=0 time=459.03 ms connected to 89.36.208.169:80 (224 bytes), seq=1 time=445.85 ms connected to 89.36.208.169:80 (224 bytes), seq=2 time=489.32 ms connected to 89.36.208.169:80 (224 bytes), seq=3 time=461.37 ms ^CGot signal 2 --- http://www.beautifulwork.org/ ping statistics --- 4 connects, 4 ok, 0.00% failed, time 5614ms round-trip min/avg/max = 445.8/463.9/489.3 ms $httping -f http://www.beautifulwork.org PING www.beautifulwork.org:80 (/): connected to 89.36.208.169:80 (224 bytes), seq=0 time=458.52 ms connected to 89.36.208.169:80 (224 bytes), seq=1 time=447.23 ms connected to 89.36.208.169:80 (224 bytes), seq=2 time=442.29 ms connected to 89.36.208.169:80 (224 bytes), seq=3 time=444.83 ms connected to 89.36.208.169:80 (224 bytes), seq=4 time=456.58 ms connected to 89.36.208.169:80 (224 bytes), seq=5 time=446.09 ms connected to 89.36.208.169:80 (224 bytes), seq=6 time=447.35 ms ^CGot signal 2 --- http://www.beautifulwork.org/ ping statistics --- 8 connects, 7 ok, 12.50% failed, time 3580ms round-trip min/avg/max = 442.3/449.0/458.5 ms $
anonymous pages and memory from /proc/meminfo
$cat /proc/meminfo MemTotal: 3495924 kB MemFree: 1465276 kB MemAvailable: 2353604 kB Buffers: 126008 kB Cached: 962924 kB SwapCached: 0 kB Active: 1330576 kB Inactive: 452848 kB Active(anon): 695532 kB Inactive(anon): 29420 kB Active(file): 635044 kB Inactive(file): 423428 kB Unevictable: 0 kB Mlocked: 0 kB SwapTotal: 7259132 kB SwapFree: 7259132 kB Dirty: 232 kB Writeback: 0 kBAnonPages: 694488 kB
Mapped: 291508 kB Shmem: 30464 kB Slab: 97912 kB SReclaimable: 65988 kB SUnreclaim: 31924 kB KernelStack: 7808 kB PageTables: 30060 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 9007092 kB Committed_AS: 3508024 kB VmallocTotal: 34359738367 kB VmallocUsed: 0 kB VmallocChunk: 0 kB HardwareCorrupted: 0 kB AnonHugePages: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 198692 kB DirectMap2M: 3432448 kB DirectMap1G: 0 kB $ https://blogs.oracle.com/cwb/entry/so_what_the_heck_is
sample session with “shopt -s cdspell” with Bash
$shopt -s checkwinsize on cmdhist on complete_fullquote on expand_aliases on extglob on extquote on force_fignore on histappend on interactive_comments on progcomp on promptvars on sourcepath on $shopt -s cdspell $shopt -s cdspell on checkwinsize on cmdhist on complete_fullquote on expand_aliases on extglob on extquote on force_fignore on histappend on interactive_comments on progcomp on promptvars on sourcepath on $shopt -s gnu bash: shopt: gnu: invalid shell option name $cd /etc/ap apache2/ apm/ apparmor/ apparmor.d/ apport/ apt/ $cd /etc/apache3 /etc/apache2 $pwd /etc/apache2 $ http://www.gnu.org/software/bash/manual/html_node/The-Shopt-Builtin.html
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 $cat l.txt >> u.txt $cat u.txt UPPERCASE hello uppercase $paste b.txt u.txt > final.txt $cat final.txt killo UPPERCASE hello hello uppercase $sort -t: -k1 final.txt hello hello killo UPPERCASE uppercase $
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
______________________________________________________
______________________________________________________________
speech-dispatcher:x:109:29:Speech Dispatcher,,,:/var/run/speech-dispatcher:/bin/sh
______________________________________________________________
__________________________________________________________________________________
rtkit:x:110:116:RealtimeKit,,,:/proc:/bin/false
_______________________________________
_______________________________________________
Debian-gdm:x:111:117:Gnome Display Manager:/var/lib/gdm3:/bin/false
______________________________________________________
___________________________________________________________________
saned:x:112:118::/var/lib/saned:/bin/false
__________________________________
__________________________________________
ntp:x:113:120::/home/ntp:/bin/false
_____________________________
___________________________________
geoclue:x:114:121::/var/lib/geoclue:/bin/false
____________________________________
______________________________________________
dnsmasq:x:115:65534:dnsmasq,,,:/var/lib/misc:/bin/false
_____________________________________________
_______________________________________________________
fetchmail:x:116:65534::/var/lib/fetchmail:/bin/false
________________________________________
____________________________________________________
vde2-net:x:117:123::/var/run/vde2:/bin/false
_________________________________
____________________________________________
timidity:x:118:125:TiMidity++ MIDI sequencer service:/etc/timidity:/bin/false
__________________________________________________________________
_____________________________________________________________________________
epmd:x:119:128::/var/run/epmd:/bin/false
_________________________________
________________________________________
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
______________________________________
_______________________________________________
systemd-timesync:x:120:129:systemd Time Synchronization,,,:/run/systemd:/bin/false
_______________________________________________________________
__________________________________________________________________________________
systemd-network:x:121:130:systemd Network Management,,,:/run/systemd/netif:/bin/false
___________________________________________________________________
_____________________________________________________________________________________
systemd-resolve:x:122:131:systemd Resolver,,,:/run/systemd/resolve:/bin/false
___________________________________________________________
_____________________________________________________________________________
systemd-bus-proxy:x:123:132:systemd Bus Proxy,,,:/run/systemd:/bin/false
____________________________________________________
________________________________________________________________________
proftpd:x:124:65534::/run/proftpd:/bin/false
__________________________________
____________________________________________
ftp:x:125:65534::/srv/ftp:/bin/false
______________________________
____________________________________
_apt:x:126:65534::/nonexistent:/bin/false
__________________________________
_________________________________________
proxy:x:13:13:proxy:/bin:/usr/sbin/nologin
__________________________________
__________________________________________
bin:x:2:2:bin:/bin:/usr/sbin/nologin
______________________________
____________________________________
www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin
_________________________________________
____________________________________________________
sys:x:3:3:sys:/dev:/usr/sbin/nologin
______________________________
____________________________________
backup:x:34:34:backup:/var/backups:/usr/sbin/nologin
___________________________________________
____________________________________________________
list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin
______________________________________________________
_____________________________________________________________
irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin
__________________________________________
________________________________________________
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin
_________________________________________________________________________
_________________________________________________________________________________
sync:x:4:65534:sync:/bin:/bin/sync
___________________________
__________________________________
games:x:5:60:games:/usr/games:/usr/sbin/nologin
_______________________________________
_______________________________________________
man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
_________________________________________
_______________________________________________
nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
_________________________________________________
__________________________________________________________
lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
_______________________________________
____________________________________________
mail:x:8:8:mail:/var/mail:/usr/sbin/nologin
____________________________________
___________________________________________
news:x:9:9:news:/var/spool/news:/usr/sbin/nologin
__________________________________________
_________________________________________________
$sort -t: -k3 --debug /etc/passwd
$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
______________________________________________________
______________________________________________________________
speech-dispatcher:x:109:29:Speech Dispatcher,,,:/var/run/speech-dispatcher:/bin/sh
______________________________________________________________
__________________________________________________________________________________
rtkit:x:110:116:RealtimeKit,,,:/proc:/bin/false
_______________________________________
_______________________________________________
Debian-gdm:x:111:117:Gnome Display Manager:/var/lib/gdm3:/bin/false
______________________________________________________
___________________________________________________________________
saned:x:112:118::/var/lib/saned:/bin/false
__________________________________
__________________________________________
ntp:x:113:120::/home/ntp:/bin/false
_____________________________
___________________________________
geoclue:x:114:121::/var/lib/geoclue:/bin/false
____________________________________
______________________________________________
dnsmasq:x:115:65534:dnsmasq,,,:/var/lib/misc:/bin/false
_____________________________________________
_______________________________________________________
fetchmail:x:116:65534::/var/lib/fetchmail:/bin/false
________________________________________
____________________________________________________
vde2-net:x:117:123::/var/run/vde2:/bin/false
_________________________________
____________________________________________
timidity:x:118:125:TiMidity++ MIDI sequencer service:/etc/timidity:/bin/false
__________________________________________________________________
_____________________________________________________________________________
epmd:x:119:128::/var/run/epmd:/bin/false
_________________________________
________________________________________
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
______________________________________
_______________________________________________
systemd-timesync:x:120:129:systemd Time Synchronization,,,:/run/systemd:/bin/false
_______________________________________________________________
__________________________________________________________________________________
systemd-network:x:121:130:systemd Network Management,,,:/run/systemd/netif:/bin/false
___________________________________________________________________
_____________________________________________________________________________________
systemd-resolve:x:122:131:systemd Resolver,,,:/run/systemd/resolve:/bin/false
___________________________________________________________
_____________________________________________________________________________
systemd-bus-proxy:x:123:132:systemd Bus Proxy,,,:/run/systemd:/bin/false
____________________________________________________
________________________________________________________________________
proftpd:x:124:65534::/run/proftpd:/bin/false
__________________________________
____________________________________________
ftp:x:125:65534::/srv/ftp:/bin/false
______________________________
____________________________________
_apt:x:126:65534::/nonexistent:/bin/false
__________________________________
_________________________________________
proxy:x:13:13:proxy:/bin:/usr/sbin/nologin
__________________________________
__________________________________________
bin:x:2:2:bin:/bin:/usr/sbin/nologin
______________________________
____________________________________
www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin
_________________________________________
____________________________________________________
sys:x:3:3:sys:/dev:/usr/sbin/nologin
______________________________
____________________________________
backup:x:34:34:backup:/var/backups:/usr/sbin/nologin
___________________________________________
____________________________________________________
list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin
______________________________________________________
_____________________________________________________________
irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin
__________________________________________
________________________________________________
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin
_________________________________________________________________________
_________________________________________________________________________________
sync:x:4:65534:sync:/bin:/bin/sync
___________________________
__________________________________
games:x:5:60:games:/usr/games:/usr/sbin/nologin
_______________________________________
_______________________________________________
man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
_________________________________________
_______________________________________________
nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
_________________________________________________
__________________________________________________________
lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
_______________________________________
____________________________________________
mail:x:8:8:mail:/var/mail:/usr/sbin/nologin
____________________________________
___________________________________________
news:x:9:9:news:/var/spool/news:/usr/sbin/nologin
__________________________________________
_________________________________________________
$
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 the public from reading private messages;[3] various aspects in information security such as data confidentiality, data integrity, authentication, and non-repudiation[4] are central to modern cryptography. Modern cryptography exists at the intersection of the disciplines of mathematics, computer science, electrical engineering, communication science, and physics. Applications of cryptography include electronic commerce, chip-based payment cards, digital currencies, computer passwords, and military communications.
ABOUT CRC
A cyclic redundancy check (CRC) is an error-detecting code commonly used in digital networks and storage devices to detect accidental changes to raw data. Blocks of data entering these systems get a short check value attached, based on the remainder of a polynomial division of their contents. On retrieval, the calculation is repeated and, in the event the check values do not match, corrective action can be taken against data corruption. CRCs can be used for error correction (see bitfilters).[1]
CRC can't fix the mistakes in frames which change the value of DE("Discard eligibility"), for example if by a mistake DE value was set from 0 to 1, CRC won't be able to return it to 0, the frame will be discarded.
CRCs are so called because the check (data verification) value is a redundancy (it expands the message without adding information) and the algorithm is based on cyclic codes. CRCs are popular because they are simple to implement in binary hardware, easy to analyze mathematically, and particularly good at detecting common errors caused by noise in transmission channels. Because the check value has a fixed length, the function that generates it is occasionally used as a hash function.
[bash]
$sudo cat /proc/crypto
name : crct10dif
driver : crct10dif-pclmul
module : crct10dif_pclmul
priority : 200
refcnt : 1
selftest : passed
internal : no
type : shash
blocksize : 1
digestsize : 2
name : crc32
driver : crc32-pclmul
module : crc32_pclmul
priority : 200
refcnt : 1
selftest : passed
internal : no
type : shash
blocksize : 1
digestsize : 4
name : crc32c
driver : crc32c-intel
module : crc32c_intel
priority : 200
refcnt : 1
selftest : passed
internal : no
type : shash
blocksize : 1
digestsize : 4
name : lzo
driver : lzo-generic
module : kernel
priority : 0
refcnt : 5
selftest : passed
internal : no
type : compression
name : crct10dif
driver : crct10dif-generic
module : kernel
priority : 100
refcnt : 2
selftest : passed
internal : no
type : shash
blocksize : 1
digestsize : 2
name : aes
driver : aes-generic
module : kernel
priority : 100
refcnt : 1
selftest : passed
internal : no
type : cipher
blocksize : 16
min keysize : 16
max keysize : 32
name : sha1
driver : sha1-generic
module : kernel
priority : 0
refcnt : 1
selftest : passed
internal : no
type : shash
blocksize : 64
digestsize : 20
name : md5
driver : md5-generic
module : kernel
priority : 0
refcnt : 1
selftest : passed
internal : no
type : shash
blocksize : 64
digestsize : 16
name : digest_null
driver : digest_null-generic
module : kernel
priority : 0
refcnt : 1
selftest : passed
internal : no
type : shash
blocksize : 1
digestsize : 0
name : compress_null
driver : compress_null-generic
module : kernel
priority : 0
refcnt : 1
selftest : passed
internal : no
type : compression
name : ecb(cipher_null)
driver : ecb-cipher_null
module : kernel
priority : 100
refcnt : 1
selftest : passed
internal : no
type : blkcipher
blocksize : 1
min keysize : 0
max keysize : 0
ivsize : 0
geniv : <default>
name : cipher_null
driver : cipher_null-generic
module : kernel
priority : 0
refcnt : 1
selftest : passed
internal : no
type : cipher
blocksize : 1
min keysize : 0
max keysize : 0
$
[/bash]
LINK
https://en.wikipedia.org/wiki/Cryptography
https://en.wikipedia.org/wiki/Cyclic_redundancy_check
https://developer.ibm.com/linuxonpower/2017/08/11/adding-power-optimized-crc-32-existing-code/