nyuuzyou/kompy huggingface dataset:
xarakteristikalari oilasi

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xarakteristikalari oilasi
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bet | 63/160 | Sana | 13.01.2024 | Hajmi | 1 Mb. | | #136728 |
Bog'liq Optik aloqa asoslari (N.Yusupov, R.Isayev)xarakteristikalari oilasi
qiymatlarida tokning keskin ortishi, ya’ni elektr teshilish hodisasi kuzatiladi (uzlukli chiziqlarga qarang).
Bipolar fototranzistorlar quyidagi parametrlar bilan tav- siflanadi:
integral sezgirlik, bipolar tranzistorlarda bu parametming qiymati fotodiodlarnikiga qaraganda bir-ikki tartibga katta bo‘ladi va bir necha yuz mA/W lami tashkil etadi;
kuchlanishning ishchi qiymatlari (10—15 V oralig‘ida);
tok kuchining ishchi qiymatlari (bir necha o‘n mA gacha);
qorong'ilik toki (bir necha yuz mkA gacha);
sochilish quwatining eng katta ruxsat etilgan qiymati (bir necha o‘n mW gacha);
chegaraviy chastota.
Qotishmali bipolar fototranzistorlaming chegaraviy chastotalari bir necha kHz larni tashkil etadi.
Planar yassi qatlamli texnologiya bo‘yicha tayyorlangan bipolar fototranzistorlar bir necha o‘n MHz largacha chastotalarda ish- laydi.
Fotosezgirligining fotodiodnikiga qaraganda kuchaytirish koef- fitsiyenti p marta kattaligi bipolar fototranzistorlaming afzalligi hisoblanadi.
Shunday qilib, bipolar fototranzistorlar fotodiodga qaraganda katta fotosezgirlikka, fotorezistorga nisbatan katta tezkorlikka ega bo‘lgan fotoqabulqilgichdir.
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www.ziyouz.com kutubxonasi
Biroq bir vaqtning o‘zida ham katta fotosezgirlikka, ham katta tezkorlikka ega bo'lgan fototranzistorlarni tayyorlash murakkab masala hisoblanadi.
Buning sababi shundaki, yorug‘lik oqimi ta’siriga sezgir baza sohasi yuza sirtining oshirilishi zaryad tashuvchilarning bu soha bo‘yicha uchib o‘tish vaqtining ortishi va fotoqabulqilgich tezkorligining kamayishiga olib keladi.
Integral ko'rinishda fotodiod va bipolar tranzistorlardan tarkib topgan fotoqabulqilgich bu muammoning hal etish imkonini beradi (4.14-rasm).
Yetarli darajada katta yuza sirtiga ega bo‘lgan fotodiod bu fotoqabulqilgich fotosezgirligi, ya’ni asbob tezkorligining ortishiga olib keladi.
rasm. Fotodiod-tranzistorning tuzilishi (a) va
elektr sxemasi (b)
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www.zivouz.com kutubxonasi
Harorat ta’siriga barqarorligining nisbatan pastligi, qorong‘ilik tokining fotodiodnikiga nisbatan o‘nlab-yuzlab marta katta ekanligi, shovqin darajasining yuqoriligi fototranzistorlarning kamchiligi hisoblanadi.
Optik uzatish tizimlarida qo‘llaniladigan
fotoqabulqilgich turlarining qiyosiy tavsifi
Yuqoridagi bayondan ma’lum bo‘ldiki, qabul qiluvchi opto- elektron modulda qo‘llash uchun mo‘ljallangan p-n tuzilishli fotodiod, p-i-n tuzilishli fotodiod, ko‘chkili fotodiod va fototran- zistorlar o'zlarining tuzilishi, ish mexanizmi, xarakteristika va parametrlari bilan farq qiladi. Awalo, shuni ta’kidlash joizki, ular man etilgan energetik sohalarining kengligi o'zaro farq qiladigan turli xil yarimo'tkazgich va yarimo'tkazgichli birikmalardan tay- yorlanadi va shu sababdan ularning ishchi to‘lqin uzunligi diapazoni bir-biridan farq qiladi (4.1-jadval).
4.1-jadval
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FIFO (fist in, fist out) usuli

Integratsiyalashuvchi funksiya
—
tovarlam i yetkazib beruv-
chidan iste’molchigacha boMgan harakati davom ida moddiy oqim
m a te ria lla rn i so tib o lish , m a h s u lo tn i ish la b c h iq a rish va
taqsimlash (sotish) bosqichlaridan o'tadi. Tovar harakatining har
bir bosqichi o ‘ziga xos xususiyatlar bilan xarakterlanadi va faqat
u nga tegishli boMgan m asalalarn i y ech ad i. Lekin u larn in g
birontasi ham tovar harakati jarayonidan tashqarida mustaqil
к о ‘rib chiqilishi m um kin emas. Bu jarayonda m uhim o ‘rinni
sotish egallaydi, u ishlab chiqarishning tashkiliy va iqtisodiy
xususiyatlarini, m ateriallar xaridining hajm ini va nom enklatu-
rasini ham da bu bosqichlarning bir-biriga m unosabatlarini asoslab
beradi.
Ishlab chiqarish - M. L. Tursunxodjayev Tashkent davlat texnika universiteli

oqim ishlab ch iq arish n i boshqarishning m arkaziy tizim idan
keladigan buyruq bo ‘yicha qabul qiluvchiga «itarib chiqarilganday»
bo!ladi.
Kafolatlangan (sug‘urta) zaxiralar
—
ta ’m inot jarayonidagi
uzilishlar yoki ishlab chiqarish hajmidagi o ‘zgarishlar vujudga
kelgan holatlarda korxonaning ishini ta ’minlash uchun zarur. Bu
zaxiralar yordam ida haqiqiy talab bashorat qilinganida ishlab
chiqarilayotgan mahsulotning haqiqiy hajmini rejalashtirilgandan
va h ar xil operatsiyalar bajarilishining haqiqiy m uddatlarini
rejadagilardan chetlanishlari qoplanadi.
signal sathi — ImW) - Optik aloqa asoslari

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Optik aloqa asoslari
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bet | 70/160 | Sana | 13.01.2024 | Hajmi | 1 Mb. | | #136728 |
Bog'liq Optik aloqa asoslari (N.Yusupov, R.Isayev)signal sathi — ImW)
ikki sathli tizimdan ko‘p sathli tizimga o‘tish, ya’ni damlash jarayonini qisqaroq to‘lqin uzunliklarida amalga oshirish maqsadga muvofiqdir.
Erbiyli optik tolalami umuman olganda 514, 528, 532, 665, 807, 980 va 1480 nm li to‘lqin uzunliklaridagi nurlanishlar bilan qo‘zg‘atish mumkin. Biroq uch sathli damlash tizimiga asoslangan zamonaviy optik tolali kuchaytirgichlarda bu maqsadda, asosan, 980 nm to‘lqin uzunlikdagi nurlanishdan foydalaniladi.
Bu to'lqin uzunligiga mos kelgan 3-barqaror sath (5.5-rasmda u 3-ES bilan belgilangan) 2-o‘ta barqaror sathga nisbatan o‘nlab marta torroq chastotalar spektriga ega.
Uch sathli damlash tizimida o‘ta barqaror 2-sathni qo‘zg‘atish ikki bosqichda amalga oshiriladi: awal 3-ES sath qo‘zg‘atiladi, natijadabu sathning elektronlar bilan egallanganligi ortadi. Elektron- larning bu sathdagi o‘rtacha yashash vaqti taxminan 1 mks ga
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www.ziyouz.com kutubxonasi
teng. Shundan so‘ng elektronlar 2-o‘ta barqaror sathning yuqori sathchalariga o‘tib, ulardan asta-sekin bu sathning boshqa sathcha- lariga tushadi. Shu tarzda 2-o‘ta barqaror sath quyi sathchalarining elektronlar bilan asosiy sathga nisbatan teskari egallanganligiga erishiladi.
Bu esa, o‘z navbatida, elektronlarning 1530... 1560 nm to‘lqin uzunlikdagi signal ta’sirida majburiy o‘tishlarning vujudga kelishiga va oxir-oqibat signal nurlanishining kuchayishiga olib keladi.
Elektronlarning 3-barqaror sathning sathchalaridan 2-o‘ta barqaror sath sathchalariga o‘tishi nisbatan past chastotali nurlanish yoki atomlarining tebranishlari (akustik fotonlar) ko‘rinishidagi energiyaning ajralib chiqishi, ya’ni shovqinning vujudga kelishiga olib keladi. Biroq 3-barqaror sathning chastotalar spektri kuchay- tirgichga nisbatan past sathli shovqinga ega bo‘ladi.
Damlash samaradorligi nuqtayi nazaridan qiyosiy tahlil birinchi qarashda uch sathli tizimda teskari egallangan muhitni hosil qilish ko‘proq energiya talab qiladi, boshqacha aytganda, bir xil kattalikdagi kuchaytirish koeffitsiyentini olish uchun /=980 nm li to‘lqin uzun- ligida damlanadigan kuchaytirgich /=1480 nm to‘lqin uzunligida ko‘proq quwat talab qiladi, degan xulosaga olib kelishi mumkin. Biroq 2-o‘ta barqaror sath asosiy sathga nisbatan yaqin joylashgani, bu sathga tegishli quyi sathchalarning elektronlar bilan egallanishi ehtimolligi juda kattaligini, shu sababdan optik signalning kuchayish jarayonida ularning hech qachon batamom bo‘shab qolmasligi e’tiblorga olinsa, damlash quwatining bir xil qiymatlarida uch sathli damlash tizimga asoslangan optik kuchaytirgich ikki sathli tizim asosida ishlaydigan optik kuchaytirgichga nisbatan kattaroq kuchaytirish koeffitsiyentiga ega bo‘lishi ma’lum bo‘ladi.
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Transport sathi protokollari TCP, UDP, RTP

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Transport sathi protokollari TCP, UDP, RTP
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bet | 45/118 | Sana | 17.05.2024 | Hajmi | 8,17 Mb. | | #240348 |
Bog'liq R. I. Isayev, D. X. Ibatova multimеdiali aloqa tarmoqlari toshke4.2.1. Transport sathi protokollari TCP, UDP, RTP
TCP (Transmission Control Protocol) protokoli. IP tarmoqlarda transportlashning ishonchliligini oshirish uchun 1974-yilda datagrammani sifatli eltishni ta’minlovchi transport sathidagi TCP protokoli ishlab chiqilgan. TCP protokoli ulanish uchun mo‘ljallangan, shuningdek TCP paketi segment deb ataladi.
UDP (User Datagram Protocol) protokoli – Internet tarmoqlarida transport protokolining boshqa namunasini o‘zida ifodalaydi. Shuningdek TCP protokoli singari, UDP protokoli datagrammani eltishni ta’minlaydi. Biroq oxirgi nuqtalar orasida ulanish o‘rnatilmagan rejimda ishlaydi.
Sarlavha va ma’lumotlar maydonidan iborat UDP protokolining paketi, UDP datagrammasi deyiladi. UDP protokoli datagrammani ishonchli yetkazishga moil emas, uning vazifasiga ma’lumotlar uzatishni boshqarish va qabul qilishni tasdiqlash kirmaydi. Oxirgi bir necha yilda UDP protokoli Internet tarmoqlarida (Voice over IP, VoIP) so‘zlashuv axborotlarini uzatishda keng qo‘llanilmoqda.
4.3-rasm. TCP/IP protokollar stekining tuzilishi
RTP (Real-time Transport Protocol) transport protokoli. RFC 1889 va RFC 1890 tavsiyalarida yozilgan haqiqiy vaqt RTP (Real-time Transport Protocol) transport protokoli, haqiqiy vaqtda uzatiladigan ma’lumotlarni ikki tomonlama yetkazish xizmatini ta’minlaydi, masalan interaktiv audio va video trafiklarni. RTP protokoli foydali yuklama turini identifikatsiyasini, paketlar ketma-ketligini raqamlash, vaqt belgisini qo‘yish va yetkazishni nazorat qilishni ta’minlaydi. Protokolda quyidagi vazifalar ko‘rib chiqilgan:
RTP protokoli, RTCP (RTP Control Protocol) boshqarish protokoli bilan birga ishlaydi. RTCP protokoli VoIP seansi ishtirokchilariga boshqarish paketlarini uzatishni ta’minlaydi. Protokolning asosiy vazifasi shundan iboratki, RTP protokoli bilan taqdim etiladigan xizmat ko‘rsatish sifati sathi haqida ishtirokchilarni xabardor qiladi. RTCP protokoli uzatilgan va yo‘qolgan paketlar soni, kechikish va djitter qiymati haqidagi axborotni yig‘adi.
Turli arxitekturaga ega tarmoqlar orasida paketlarni uzatishni IP stekining asosiy protokoli ta’minlaydi. IP datagrammali protokol paketlarni ishonchli uzatishni kafolatlamaydi. Biroq ko‘pgina tarmoqlar orqali ma’lumotlar uzatishda o‘tkazish qobiliyatini oshiradi.
Shuningdek tarmoq sathida quyidagi protokollar qo‘llaniladi:
ICMP (Internet Control Message Protocol) boshqarish protokoli, xatoliklar va uzatishdagi uzilishlar haqida tarmoq uzellariga axborot uzatadi;
adreslar muammolarini yechish protokollari: ARP (Address Resolution Protocol) tarmoq uzelining fizik adresiga (MAC –stansiya adresi) IP adresni o‘zgartiradi; RARP (Reverse Address Resolution Protocol) teskari funksiyani bajaradi, ya’ni MAC adres yordamida IP adresni aniqlaydi.
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| Chapter 7: Wireless Security Testing

that would include the relevant radio headers, though you would need to tell
airodump-ng
that you wanted to write out the files. Otherwise, you would just get
output to the screen.
You would pass
-w
and a prefix to the command. The prefix is
used to create the files,
including a
.cap
file.
Once you have your
.cap
file, you also need a password file. Fortunately, Kali has sev‐
eral of them in
/usr/share/wordlists
. You can also download others from online sour‐
ces. These are dictionaries that would have to include
the password or passphrase
used by the wireless network. Just as with any password attack, you won’t be success‐
ful unless the actual password is in the dictionary you are using. This is because the
brute-force attack will compare what was captured against
what was generated from
the password. Once you have those elements, you could take a run at cracking the
passwords with something like the following command:
cowpatty -r test-03.cap
-
f
/usr/share/wordlists/nmap.lst -s TP-Link_862C
.
Aircrack-ng
We’ve been using tools from the Aircrack-ng suite but we haven’t
talked about using
aircrack-ng
to crack passwords. It’s a powerful tool that can crack WEP and WPA
passwords. What
aircrack-ng
needs is a large collection of packets that can be used to
crack against. What
aircrack-ng
does is a statistical analysis
from the packets captured
by using a password file to compare against. The short version of what could be a
much longer description (and if you are interested in a longer version,
you can read
the
documentation
) is that it’s all math and not just hashing and comparing. The pro‐
gram does a byte-by-byte analysis to obtain the passphrase used.
Network Security Testing | 47

This is not to say that you need to always specify all of the fields. You can specify what
you want, and
hping3
will fill the rest of the fields in the
IP and transport headers as
normal.
hping3
is capable of flooding by not bothering to wait for any responses or
even bothering to use any waiting periods. The tool will send out as much traffic as it
can, as fast as it can. You can see the output from the tool in
Example 2-5
.
Example 2-5. Using hping3 for flooding
root@rosebud:~# hping3 --flood -S -p
80
192.168.86.1
HPING 192.168.86.1
(
eth0 192.168.86.1
)
: S
set
,
40
headers +
0
data bytes
hping
in flood mode, no replies will be shown
^C
--- 192.168.86.1 hping statistic ---
75425
packets transmitted,
0
packets received, 100%
packet loss
round-trip min/avg/max
=
0.0/0.0/0.0 ms
When I ran this, I was connected to my Kali system remotely. As soon as I started it
up, I tried to kill it because I had the output I was looking for. However, the system
was cramming packets down the wire (and getting responses) as fast as it could. This
made it hard to get the Ctrl-C I was trying to send to my Kali system,
meaning
hping3
wasn’t dying—it was just merrily sending a lot of packets out into the network (fortu‐
nately, I used my local network to test on, rather than trying to test someone else’s
system). The operating system and network were otherwise engaged, so there was no
response for a long period of time. In
Example 2-5
, I am using
hping3
to
send SYN
messages to port 80. This is a SYN flood. In this example, I’m not only testing the
ability of the system to handle the flood at the network stack (operating system) with
just the capability of the hardware and operating system to respond to the traffic, but
also testing the transport layer.
The operating system has to hold out a small chunk of memory with Transport Con‐
trol Protocol (TCP) connections. Years ago, the number of slots available for these
initial
messages, called
half-open connections
, wasn’t very large. The expectation was
that the connecting system was well-behaved and it would complete the connection,
at which point it was up to the application to manage. Once the number of slots avail‐
able to take half-open
connections is exhausted, no new connections, including con‐
nections from legitimate clients, will be accepted. These days, most systems are far
more capable of handling SYN floods. The operating system
will just handle these
inbound, half-open connections and dispose of them using a variety of techniques,
including reducing the timeout period during which the connection is allowed to be
half-open.
This test uses SYN messages (
-S
) to port 80 (
-p 80
). The idea is that we should get a
SYN/ACK message back as the second stage of the three-way handshake. I don’t have
to specify a protocol because that’s accomplished by just saying that I want to send a
SYN message. TCP is the only protocol that has the SYN message. Finally, I tell
SUA va IUA protokollari - R. I. Isayev, D. X. Ibatova multimеdiali aloqa tarmoqlari toshkent 2018 udk: 621. 391 Bbk 32. 94 G95

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R. I. Isayev, D. X. Ibatova multimеdiali aloqa tarmoqlari toshkent 2018 udk: 621. 391 Bbk 32. 94 G95
|
bet | 54/118 | Sana | 17.05.2024 | Hajmi | 8,17 Mb. | | #240348 |
Bog'liq R. I. Isayev, D. X. Ibatova multimеdiali aloqa tarmoqlari toshkeSUA va IUA protokollari. SCCP foydalanuvchilari uchun moslashish sathining SUA protokoli, IP-tarmoq bo‘ylab SCCP foydalanuvchilarning signalli xabarlarini o‘tkazishni ta’minlaydi, masalan, TCAP yoki INAP, SUA protokoli IP-tarmoq signalizatsiyaning oxirgi punktlari va signalizatsiya shlyuzlari orasida qo‘llaniladi.
SUA protokoli, SCCP xizmatlar singari tartibsiz va tartiblangan yetkazish bilan ulanishsiz, ma’lumotlar oqimini boshqarishli yoki boshqarishsiz ulanishlarga mo‘ljallangan xizmatlar va xabarlarni o‘z vaqtida yetkazilmaganligi natijasidagi xatolar va xabarlarning yo‘qolganligini bilish xizmatlarini ta’minlaydi (ya’ni SCCP 0 dan 3 gacha xizmatlar sinfi). Ulanishsiz xizmat holatida SCCP va SUA protokollari signalizatsiya shlyuzida o‘zaro ta’sirlashadi.
ISDN - foydalanuvchi (IUA) uchun moslashish sathining protokoli IP tarmoq orqali Q.931 xabarni o‘tkazishni ta’minlaydi. IUA protokoli MTP protokolining qismini signalizatsiya tizimida qo‘llanilishini ta’qiqlaydi va yuqori sathning ilovalarini SCTP transport protokollar bilan bevosita o‘zaro ta’sirlashishiga imkon beradi.
Multimediali aloqa tarmoqlarida sinxronizatsiya
Sinxronizatsiya deganda aloqa tarmog‘ining funksional elementlari bilan axborotni uzatish, kommutatsiyalash va ishlov berishning ayrim muhim elementlari orasida muvofiqlashtirish tadbiri tushuniladi. “Sinxronizatsiya” atamasi aloqa tarmog‘i va uning ayrim elementlarining faoliyat yuritishini turli jarayonlarini tavsiflash uchun qo‘llaniladi. Raqamli UFTTga nisbatan sinxronizatsiyaning uchta jixatini ko‘rib chiqish maqsadga muvofiqdir:
- taktli sinxronizatsiya;
- siklli sinxronizatsiya;
- tarmoq sinxronizatsiyasi.
Taktli sinxronizatsiya, umumiy bitlar oqimidan sinxronizatsiya signalini ajratib olishga asoslangan. U bitlar darajasida (taktli intervallar) uzatish va qabul qilish qurilmalarining ishlashini vaqt bo‘yicha moslashtirish uchun zarur. Siklli sinxronizatsiya, turli manbalardan kelayotgan axborotlar, bitlarning umumiy oqimida axborotlar blokining boshi va oxirini aniqlash uchun zarur, ya’ni uni qabul qilishda to‘g‘ri taqsimlash uchun. Tarmoq sinxronizatsiyasi, axborot uzatishda yuqori sifat taminlanishi uchun tarmoqning turli nuqtalarida (shu jumladan xalqaro ulanishlarda) taktli signallarning uzoq muddatli aniqliligi va barqarorligining berilgan ko‘rsatkichlarini ta’minlaydi.
Tarmoq sinxronizatsiya uchun kvars va atom generatorlaridan foydalaniladi. Ular yuqori aniqlikdagi etalon signallarni ishlab chiqaradi. Masalan odatdagi kvars generatorining barqarorligi bir yilda 10-6 ni tashkil etadi. Rubidiyli, seziyli va vodorodli atom generatorlarining barqarorligi ancha yuqori. Xususan, seziyli generator bir yilda 10-13 barqarorlikni taminlaydi.
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Password Cracking on WiFi | 219

Authentication
Code Protocol, Counter Mode CBC-MAC Protocol, or CCM mode
protocol (CCMP). Unfortunately, the one that is using WPA and not WPA2 is not
one
of my networks, so I can’t do any testing on it. Instead, we’re going to be using an
AP I own that isn’t being used for anything other than testing. We’ll use
besside-ng
to
attempt to crack the authentication for that BSSID. You need to use -b with the
BSSID, as you can see in
Example 7-7
. You also need to specify the interface used.
You’ll see
wlan0mon
is used,
but in order to use it, I stopped
airmon-ng
.
Example 7-7. Using besside-ng to automatically crack passwords
yazpistachio:root~# besside-ng -b 50:C7:BF:82:86:2C wlan0mon
[
19:55:52
]
Let
'
s ride
[
19:55:52
]
Resuming from besside.log
[
19:55:52
]
Appending to wpa.cap
[
19:55:52
]
Appending to wep.cap
[
19:55:52
]
Logging to besside.log
UNHANDLED MGMT 10cking
[
TP-Link_862C
]
WPA
- PING
UNHANDLED MGMT 10cking
[
TP-Link_862C
]
WPA - PING
UNHANDLED MGMT 10cking
[
TP-Link_862C
]
WPA - PING
UNHANDLED MGMT 10cking
[
TP-Link_862C
]
WPA - PING
UNHANDLED MGMT 10cking
[
TP-Link_862C
]
WPA - PING
UNHANDLED MGMT 10cking
[
TP-Link_862C
]
WPA - PING
UNHANDLED MGMT 10cking
[
TP-Link_862C
]
WPA - PING
[
19:55:59
]
\
Attacking
[
TP-Link_862C
]
WPA - DEAUTH
You’ll see from the example that
besside-ng
is
sending a
DEAUTH
. This is a deauthen‐
tication message. It’s used to force clients to reauthenticate in order to collect the
authentication message. Once the authentication message has been collected, the pro‐
gram can perform a brute-force attack in order to determine the passphrase or
authentication credentials used. We are attacking a WPA2-encrypted network, but if
we had
found a WEP-encrypted network, we could have used
wesside-ng
.
A deauthentication attack can also be used as a denial of service. By
injecting deauthentication messages to the network, an attacker can
force a client off the network. By continually repeating the deau‐
thentication message, the client may be stuck in an authentication/
deauthentication cycle and never be able to get on the network.
coWPAtty
Another program we can use to
try to crack passwords is
cowpatty
. This is styled
coWPAtty
, to make it clear it’s an attack against WPA passwords. What
cowpatty
needs in order to crack the password is a packet capture that contains the four-way
handshake used to set up the encryption key for encrypting the transmission between
the AP and the station. You can get a packet capture including
the relevant frames by
using
airodump-ng
or
kismet
. Either will generate a packet capture file (
.cap
or
.pcap
)
Network Security Testing | 49

Example 2-6. SIP invite flood
root@rosebud:~# inviteflood eth0 kilroy dummy.com 192.168.86.238 150000
inviteflood - Version 2.0
June 09, 2006
source
IPv4 addr:port
=
192.168.86.35:9
dest IPv4 addr:port
=
192.168.86.238:5060
targeted
UA
=
kilroy@dummy.com
Flooding destination with
150000
packets
sent: 150000
We can break down what is happening on the command line. First, we specify the
interface that
inviteflood
is supposed to use to send the messages out. Next, is the
username.
Since SIP is a VoIP protocol, it’s possible that this may be a number, like a
phone number. In this case, I am targeting a SIP server that was configured with user‐
names. Following the username is the domain for the username. This may be an IP
address, depending on how the target server is configured. If you don’t know the
domain
for the users, you could try using the IP address of the target system. In that
case, you’d have the same value twice, since the target is the next value on the com‐
mand line. At the end is the number of requests to send. That 150,000 requests took
seconds
to send off, meaning that the server was capable of supporting a large volume
of requests per second.
Before moving on to other matters, we need to talk about IPv6. While it isn’t yet com‐
monly used as a network protocol across the internet, meaning I couldn’t send IPv6
traffic
from my system to, say, Google’s website, the time will come when that should
be possible. I mention Google in particular because Google publishes an IPv6 address
through its Domain Name System (DNS) servers. Beyond being able to send IPv6
through the internet, though, is the fact that some enterprises are using IPv6
today to
carry traffic within their own enclaves. However, even though IPv6 is more than 20
years old, it has not had the same run-in time that IPv4 has had—and it took decades
to chase some of the most egregious bugs out of various IPv4 implementations. This
is all to say that in spite of the time that operating system vendors like Microsoft and
the Linux team have put into development and testing, more
real-world testing across
a wide variety of devices is still needed to be comprehensive.
This is all to say that Kali includes IPv6 testing tool suites. There are two of them, and
each suite has a good-sized collection of tools because in the end, IPv6 includes more
than just changes to addressing. A complete implementation of IPv6
includes
addressing, host configuration, security, multicasting,
large datagrams, router pro‐
cessing, and a few other differences. Since these are different functional areas, multi‐
ple scripts are necessary to handle those areas.
| Chapter 2: Network Security Testing Basics

test type
: SLOW HEADERS
number of connections: 50
URL: http://192.168.86.35/
verb: GET
Content-Length header value: 4096
follow up data max size: 68
interval between follow up data:
10
seconds
connections per seconds: 50
probe connection timeout:
5
seconds
test
duration:
240
seconds
using proxy: no proxy
Thu Nov
23
19:53:52 2017:
slow HTTP
test
status on 25th second:
initializing: 0
pending: 0
connected: 30
error: 0
closed: 20
service available: YES
Thu Nov
23
19:53:54 2017:
Test ended on 26th second
Exit status:
No open connections left
The Apache server targeted here uses multiple child processes and multiple threads to
handle requests. Caps are set in the Apache configuration: the default here is 2
servers, a thread limit of 64, 25 threads per child, and a maximum of 150 request
workers. As soon as the number of connections available was maxed out by
slow‐
httptest
, the number of Apache processes was 54 on this system. That would be 53
child processes and a master or parent process. To handle
the number of connections
required for the requests being made, Apache spawned multiple children and would
have had multiple threads per child. That’s a lot of processes that have been started
up. Considering that the Apache server that was running
was completely up-to-date
at the time of this writing, it seems clear that these types of attacks can be successful,
in spite of how many years they have been around. Of course,
as noted earlier, that
entirely depends on the architecture of the site under test.
SSL-based stress testing
Another resource-based attack that isn’t about bandwidth, but instead is about pro‐
cessor utilization, targets the processing requirements for encryption.
For a long
time, e-commerce sites have used Secure Sockets Layer (SSL) or Transport Layer
Security (TLS) to maintain encryption between the client and the server in order to
ensure the privacy of all communication. These days, many servers use SSL/TLS as a
matter of course. If you
attempt to search at Google, you will see that it is encrypted
by default. Similarly, many other large sites,
such as Microsoft and Apple, encrypt all
traffic by default. If you try to visit the site by using an unencrypted uniform resource
| Chapter 2: Network Security Testing Basics

Once you have the configuration set, you can run
fragroute
on the system where you
are originating traffic. If you can use it on a device that is capable of routing, you can
manipulate traffic passing
from one network to another, but this is generally going to
be something to test from a single system. Testing out the fragmentation on my local
network, I used the command line in
Example 2-4
and received the results that you
can see. The testing of the system was done by just issuing ping requests to the target.
I could have just easily done testing against another system
using traffic like web
requests.
Example 2-4. fragroute output using rules file
root@kali:~# fragroute -f frag.rules 192.168.86.1
fragroute: ip_chaff -> ip_frag -> drop -> dup -> order -> print
192.168.86.227 > 192.168.86.1: icmp:
type
8
code 0
192.168.86.227 > 192.168.86.1: icmp:
type
77
code 74
192.168.86.227 > 192.168.86.1: icmp:
type
8
code 0
192.168.86.227 > 192.168.86.1: icmp:
type
90
code 83
192.168.86.227 > 192.168.86.1: icmp:
type
8
code 0
192.168.86.227 > 192.168.86.1: icmp:
type
90
code 83
192.168.86.227 > 192.168.86.1: icmp:
type
102
code 77
192.168.86.227 > 192.168.86.1: icmp:
type
102
code 77
192.168.86.227 > 192.168.86.1: icmp:
type
8
code 0
Floating point exception
The interesting thing we see in this test is the floating-point error. This happened in
fragroute
from just manipulating the traffic. This particular testing appears to have
turned
up a bug in
fragroute
. The unfortunate thing is that once the floating-point
error happened, network communication stopped. I was no longer able to get any
network traffic off my Kali box, because of the way
fragroute
works.
All traffic is set
up to run through
fragroute
, but when the program fails, the hook doesn’t get unset.
As a result, the operating system is trying to send network communication to some‐
thing that just isn’t there. This is another example of the reason we test. Software can
be complex, and especially when underlying
libraries have changed, behaviors can
also change.
Ultimately, any failure resulting from a stress test is a problem with availability. If the
system crashes, no one can get to anything. If the application fails, the service isn’t
available to users. What you are performing is a denial-of-service attack. As a result,
it’s important to be careful when performing these sorts of attacks. There are defi‐
nitely
ethical implications, as noted earlier, but there are also very real possibilities to
cause damage, including significant outage to customer-facing services. More on that
in a moment. A simple way to do stress testing is to use a tool like
hping3
. This fabu‐
lous tool can be used to craft packets on the command line. Essentially, you tell
hping3
what you want
different fields to be set to, and it will create the packet the way
you want.
Denial-of-Service Tools - Learning Kali Linux

unlimited resources at their disposal. Often there are caps on the connections the
application server will take on. This depends on how the application is designed, and
not all web servers are susceptible to these attacks. One thing to note here is that
embedded devices often have limited resources when it comes to their memory and
processor. Think about any device that has a web server for remote management—
your wireless access point, your cable modem/router, a printer.
These devices have
web servers to make management easier, but the primary purpose of these devices
isn’t to provide web services; it’s to act as a wireless access point, a cable modem/
router, or a printer. The resources for these devices will be primarily applied to the
device’s intended function.
These devices are one place
to use this sort of testing, because they simply won’t
expect a lot of connections. This means that an attack such as Slowloris may be able
to take these servers offline, denying service to anyone else who may try to connect.
The Slowloris attack is designed to hold a lot of connections open to a web server.
The difference between this attack and a flooding attack is this is a slow play attack.
It’s not a flood. Instead, the attack tool holds the connection open by sending small
amounts of data over a long period of time. The server will maintain these connec‐
tions as long as the attack tool continues to send even small amounts of data partial
requests that never quite get completed.
Slowloris is not the only type of attack that goes after web servers, though.
In recent
years, there have been a few vulnerabilities that go after web servers. Another one is
Apache Killer, which sends bytes in chunks that overlap. The web server, in trying to
put the chunks together, eventually runs out of memory trying to make it work cor‐
rectly. This was a vulnerability found in both the 1.x and 2.x versions of Apache.
One program that Kali has available is
slowhttptest
. Using
slowhttptest
,
you can launch
one of four HTTP attacks at your target. The first is a slow headers attack, otherwise
known as Slowloris (as noted previously). The second is a slow body attack, otherwise
known as R-U-Dead-Yet. The range attack,
known as Apache Killer, is also available,
as is a slow read attack. All of these are essentially the reverse of the flooding attacks
discussed earlier in that they accomplish the denial of service with a limited number
of network messages. In
Example 2-7
, the default slow headers attack (Slowloris) was
run against Apache on my Kali box. No traffic has left my system, and you can see
that after the 26th second, the test ended with no connections left available. Of
course, this was a simply configured web server with very few threads configured. A
web application with multiple web servers available
to manage load would survive
considerably longer, if they were available at all.
Example 2-7. slowhttp output
slowhttptest version 1.6
- https://code.google.com/p/slowhttptest/ -
Password Cracking on WiFi

it’s worth keeping that in mind. The other encryption mechanism that you will run
across is some form of WPA. Again, you shouldn’t see WPA, but instead you should
see WPA2.
If you run across WPA, you should strongly encourage that it be replaced
with WPA2.
besside-ng
The first tool we will take a look at is
besside-ng
. Before we do that, though, we’re
going to scan for BSSIDs again, though we’ll do it in a different way. We’re going to
use
another tool from the
aircrack-ng
package. This tool puts your wireless interface
into monitor mode and in the process creates another interface that can be used to
dump traffic on. To enable monitor mode, we use
airmon-ng start wlan0
when the
wireless interface is
wlan0
. Once
airmon-ng
is started,
the interface
wlan0mon
is cre‐
ated.
airmon-ng
will tell you the name of the interface that’s created, since yours may
be different. Once we have monitor mode enabled, we can use
airodump-ng
wlan0mon
to monitor the traffic with the radio headers, which is enabled by
airmon-
ng
.
Example 7-6
shows
the output from
airodump-ng
.
Example 7-6. Using airodump-ng
CH
10
][
Elapsed:
6
mins
][
2018-02-25 19:41
BSSID PWR Beacons
#Data, #/s CH MB ENC CIPHER AUTH ESSID
78:28:CA:09:8E:41 -1
0
16
0
1
-1 WPA
70:3A:CB:52:AB:FC -10
180
259
0
1
54e. WPA2 CCMP PSK CasaC
18:D6:C7:7D:EE:11 -29
198
121
0
1
54e. WPA2 CCMP PSK CasaC
70:3A:CB:4A:41:3B -44
162
92
0
11
54e. WPA2 CCMP PSK CasaC
C4:EA:1D:D3:78:39 -46
183
0
0
6
54e WPA2 CCMP PSK Centu
50:C7:BF:82:86:2C -46
118
0
0
5
54e. WPA2
CCMP PSK TP-Liq
C4:EA:1D:D3:80:19 -49
57
39
0
6
54e WPA2 CCMP PSK Centuq
q
BSSID STATION PWR Rate Lost Frames Probe
(
not associated
)
1A:BD:33:9B:D4:59 -20
0
-
1
0
6
(
not associated
)
26:D6:B6:BE:08:7A -42
0
-
1
0
6
(
not associated
)
44:61:32:D6:46:A3 -46
0
-
1
0
90
CasaChien
(
not associated
)
64:52:99:50:48:94 -48
0
-
1
0
12
WifiMyqGdo
(
not associated
)
F4:F5:D8:A2:EA:AA -46
0
-
1
0
3
CasaChien
78:28:CA:09:8E:41 94:9F:3E:01:10:FB -28 0e-
0
79
53
Sonos_lHe9q
70:3A:CB:52:AB:FC 94:9F:3E:01:10:FA -26
36
-24
0
101
70:3A:CB:52:AB:FC C8:DB:26:02:89:62 -1 0e-
0
0
3
70:3A:CB:52:AB:FC 94:9F:3E:00:FD:82 -36
0
-24
0
27
18:D6:C7:7D:EE:11 44:61:32:8C:02:9A -46
0
- 1e
240
117
CasaChien
This gives us the list of BSSIDs as well as the encryption details. We know that most
of them are using WPA2 with the Counter Mode Cipher
Block Chaining Message
Transmission moylarning asosiy fizikaviy-kimyoviy xususiyatlari

150
Moylarni almashtirish muddatlari. Moylarni almashtirish
muddatlarini belgilash mezoni sifatida ko‘pchilik hollarda moylar-
ning fizikaviykimyoviy ko‘rsatkichlari (qovushoqlik, kislotalilik,
tarkibidagi aktiv elementlar miqdori), moyning yemirilishga qarshi
xususiyatlarining o‘zgarishi, shuningdek, transmissiya agregatlari
detallarining holati qaraladi. Moyni almashtirish zaruratini belgi-
lovchi omillardan biri moy qovushoqligining me’yordan 50 foizga
ortishidir. Zamonaviy yengil avtomobillarning transmission moy-
larini almashtirish muddatlari turlicha va 60–75 ming km masofa
bosib o‘tilganidan so‘ng amalga oshiriladi. Ba’zi yengil avtomobil-
larda transmission moylar butun ish muddati davomida almashtiril-
maydi. Bunday moylar gipoid uzatmali yetakchi ko‘priklarda sinab
ko‘rilmoqda.
Yuk avtomobillarining transmission moylari, odatda, bir yil-
da bir martadan ortiq almashtirilmaydi, ekspluatatsiya sharoitiga
bog‘liq holda moyni almashtirish muddati 24–72 ming km deb
belgilangan. Alohida olingan moylarning almashtirish muddatlari
quyidagicha belgilangan: TCгип moyi uchun 24–30 ming km;
ТАД–17 moyi uchun 60–80 ming km; TAп–15B moyi uchun 24–
72 ming km; TCп–15K moyi uchun 36–72 ming km; TCп–10 moyi
uchun 35–50 ming km; TCп–14gip moyi uchun 36 ming km.
Respublikamiz mustaqillikka erishganidan so‘ng, avtomobil
xo‘jaligida xorijiy firmalar tomonidan ishlab chiqarilgan transmis-
sion moylar ham keng foydalanilmoqda. Shuning uchun respublika-
mizda, qolaversa, MDH davlatlarida ishlatilayotgan transmission
moylarning xorijiy firmalar moylari bilan o‘zaro almashuvchaligini
bilish muhim ahamiyatga ega (5. 9- jadval).
5. 9-jadval
Transmission moylar tarkibi - K. J. Matkarimov b. J. Mahmudov a. A. Norqulov avtomobillarda ishlatiladigan ashyolar

142
yordamida tozalangan ekstratlari yoki parafinning moysizlantirish
filtrlariga И–20 yoki И–45 sanoat moylari qo‘shib tayyorlanadi.
So‘nggi yillarda bu maqsadda selektiv
usulda tozalangan yuqori
sifatli moylar (TC–14,5 va boshqalar)dan foydalanilmoqda. Bu
moylar distillat aralashmalari ko‘rinishida bo‘lib, ularga turli xil
qo‘shilmalar qo‘shilganida hosil bo‘ladigan moyning
moylash xu-
susiyati va yuqori haroratlardagi turg‘unligi yaxshi bo‘ladi hamda
bu moylardan havo harorati minus 30–35°C dan minus 50°C gacha
bo‘lganida foydalanish mumkin.
Barncha mavsumlarda ishlatiladigan universal transmission
moylar hamda gidromexanik va gidrohajmiy
uzatmalar uchun moy-
lar yuqori tozalikdagi moylarga (ACB–5 turidagi) quyi molekular
polimerlar qo‘shib tayyorlanadi.
TCn–15K moyi - K. J. Matkarimov b. J. Mahmudov a. A. Norqulov avtomobillarda ishlatiladigan ashyolar

148
yuk avtomobillari balansirli osmasi gupchaklarini moylash uchun
ishlatiladi.
TC moyi (uzatmalar qutisi va rul boshqarmasi uchun moy)
uzatmalar qutisi karterlarida, rul boshqarmasida («Москвич»,
«Запорожец», ГАЗ–24 «Волга»), shuningdek, yengil avtomo
billarning yarim o‘qlari kardanli sharnirini moylash uchun («За
порожец») ishlatiladi.
ТСгип moyi yengil avtomobillarning gipoid uzatmalarida
(ИЖ), gipoidli yetakchi ko‘priklarning karterlarida («Москвич»,
ГАЗ–24 «Волга») ishlatiladi. Yuk avtomobillarining gipoidli uzat-
malarida bu moydan foydalanish taqiqlanadi.
ТСп–14 гип moyi faqat ГАЗ–53А, ГАЗ–53–12, ЗИЛ–130–80,
ЗИЛ–133ГЯ yuk avtomobillarida, КАвЗ–685 va ПАЗ–672 avto-
buslari gipoidli uzatmalarida ishlatiladi.
A markali moy yo‘lsiz joylardan yuradigan avtomobillar (БелАЗ
va МоАЗ avtomobillari) platformasini ko‘tarish mexanizmi va rul
mexanizmi gidrokuchaytirgichining birlashgan gidravlik tizimlari-
da ishlatiladi.
P markali moy barcha markadagi avtomobillar va avtobus-
larning rul boohqarmasi gidrokuchaytirgichi tizimlarida, shuning-
dek, avtomobillar platformasini ko‘tarish mexanizmining silindr-
larida (KpAЗ–256B1) ishlatiladi.
Transmission moylarning sitati ularni laboratoriya, stend va eks-
pluatatsiya sharoitlarida sinash natijalari asosida baholanadi. Labo-
ratoriya sharoitida sinashda moylarning fizikaviykimyoviy xusu-
siyatlari aniqlanadi: zichligi, kinematik va dinamik qovu shoqligi,
o‘t olish harorati, qotish harorati, issiqlik ta’siriga turg‘unligi,
tarkibidagi mexanik aralashmalar va suv miqdori, mis va po‘lat
plastinkalarga korrozion ta’siri, kislotaliligi, moylash xususiyati
va boshqalar. Sinash natijasida olingan ma’lumotlar me’yorlangan
ko‘rsatkichlar bilan solishtiriladi. Bir qator nisbatan keng foyda-
lanilayotgan transmission moylarning asosiy fizikaviykimyoviy
xususiyatlari 5. 8- jadvalda keltirilgan.
149
5. 8- jadval
Oksidlanishga qarshi turg‘unligi - K. J. Matkarimov b. J. Mahmudov a. A. Norqulov avtomobillarda ishlatiladigan ashyolar

146
Moy qovushoqligining ortishi, o‘z navbatida, moyning qovusho-
qlik-harorat xususiyatlarini yomonlashtiradi. Kislotaliligining orti-
shi esa podshipnik va boshqa detallarning yemirilishiga olib keladi.
Moyning oksidlanishga qarshi xususiyati issiqlik ta’sirida oksid-
lanish turg‘unligi deb baholanadi. Bu ko‘rsatkich ДК–2–НАМИ
asbobida yoki moyning yuqori haroratlarda ishlaydigan ish sharoit-
iga yaqin sharoit yaratiladigan boshqa asboblar yordamida aniqla-
nadi. Tajriba o‘tkaziladigan harorat va tajriba davomiyligi moy tur-
lari bo‘yicha Davlat standarti va texnik shartlarga asosan tanlanadi.
Transmission moylarning oksidlanishga qarshi xususiyatini
yaxshilash uchun ularga detallar yuzasida aktiv bo‘lmagan parda
hosil qiluvchi qo‘shilmalar qo‘shiladi. Bunday qo‘shilmalar sifa-
tida oltingugurt, fosfor yoki oltingugurt va fosforli birikmalardan
foydalaniladi.
Transmission moylarning konstruksion materiallarga ta’siri
Davlat standartlari asosida baholanadi.
5. 2. 2. Transmission moylarning markalanishi
Transmission moylarning markasi harflar va chiziqchadan keyin
100°C dagi kinematik qovushoqligi yozib ifodalanadi. Moyning
shartli belgisida yana uning o‘ziga xos xususiyatlarini ko‘rsatuv-
chi harflar ham yoziladi (masalan, gidromexanik yuritmalar uchun
mo‘ljallangan maxsus moylar
A harfi bilan, rul boshqarmasining
gidrokuchaytirgichida ishlatiladigan moy
P harfi bilan markala
nadi).
Transmission moylarning o‘zaro almashuvchanligi

Transmission moylarning o‘zaro almashuvchanligi MDHda ishlatiladigan moylar Xorijiy firmalar Shell Mobil BP Esso TAп–15V, TCп–15K
Shell
Spirak
90EP
MobilubeC
90
BP Gear
oil EP SAE
90
Esso Gearoil
EP 90
151
5. 9-jadvalning davomi TCп–10
Shell
Spirak
80EP
Mobilu-
beCX SAE
90
BP Multi
Gear oil
80/90 EP
Esso
Gearoil CP
80
ТСгип
Shell
Spirak EP
SAE 140
Mobilu-
beCX SAE
140
BPGear oil
Esso
Gearoil GP
140
ТСп–14гип
Shell
Spirak EP
SAE 90
Mobilube
HD 90
BP
Hypogear
SAE 90
Esso
Gearoil CX
SAE 90
ТАД–17
Spirak
90HD
Mobil GX
90
BP Multi
Gear SAE
90 EP
Esso
Gearoil 90
EP
Gidrotransformatorlar
va avtomatik uzatmalar
qutisi uchun A markali
moy
Shell Do-
nax T6
Mobil ATF
200 Type
A
BP ATF
Type A
Suffix A
Esso
Automatic
Transmission
Fluid
Rul gidrokuchaytirgichi
va gidrohajmiy uzatma-
lar uchun P markali moy
Shell Tel-
lus T
Mobilfluid
93
BP ATF
Type A
Suffix A
Esso Torque
Fluid 40
Nazorat savollari 1. Moyning vazifasi nimadan iborat?
2. Avtomobil moylari qanday olinadi?
3. Moy dvigatelda qanday sharoitda ishlaydi?
4. Motor moylariga qanday ekspluatatsion talablar qo‘yiladi?
5. Motor moylarining xususiyatlarini aytib bering.
6. Motor moylari qanday tasniflanadi?
7. Moylar qanday markalanadi?
8. Qovushoqlik indeksi deganda nimani tushunasiz?
9. Moylarga qanday qo‘shilmalar qo‘shiladi?
10. Dvigatel ishlaganida moylarning xossalari qanday o‘zgaradi?
11. Motor moylari qanday regeneratsiya qilinadi?
12. Transmission moylarning ish sharoitlari qanday?
13. Transmission moylarning asosiy ekspluatatsion xossalarini ayting.
14. Transmission moylarning turlarini aytib bering.
15. Transmission moylarning markalanishini aytib bering.
152
VI BOB. AVTOMOBIL PLASTIK SURKOV MOYLARI 6. 1. Plastik surkov moylarining umumiy xususiyatlari Plastik surkov moylari avtomobillarning, asosan, germetik ber-
ki tilmagan (karterlar ichiga joylashtirilmagan) ishqalanib ishlay-
digan tarmoqlarini moylash uchun ishlatiladi. Bunday moylar anti
Optik tarmoq paketlar kommutatsiyasili tarmoq

|
Optik tarmoq paketlar kommutatsiyasili tarmoq
|
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Bog'liq Optik aloqa asoslari (N.Yusupov, R.Isayev)12.4.3. Optik tarmoq paketlar kommutatsiyasili tarmoq
Kanallari kommutatsiyali optik kanallar to‘liq holda oxirgi tarmoq bo‘g‘inlari tomonidan istalgan ilovalardan foydalanish uchun shaffof bo‘lgan optik magistrallarni qurishga imkon beradi. Ammo bu afzalligi bilan bir qatorda ularning bir kamchiligi kanallar kommutatsiyali tarmoqlar ma’lumotlarni uzatish mahalliy tarmoqlaridan «portlash grafigi» bilan ishlay olmaydi.
Shu munosabat bilan paketlar kommutatsiyali to‘liq optik tarmoqlarni joriy qilish ideal bo‘lar edi, chunki ular tolali-optik aloqa kanallarini o'tkazishning ajratilgan polosasidan ancha samarali foydalanishga imkon beradi.
Paketlar kommutatsiyali AON ning xususiyatlari:
AON da paketlar kommutatsiyasi tarmoqlar rivojlanishning mutlaqo yangi yo'nalishni ifoda etadi. Bu marshrutlashtirishning mutlaqo yangi sxemalari, AON texnologiyasiga mo'ljallangan yangi arxitekturalar ishlab chiqilishi kerak;
optik oqimlar marshrutlashtirilishining barcha sxemalari paketlar kommutatsiyali barcha AON uchun bir xil bo'lishi kerak. Kanallar kommutatsiyali tarmoqlar uchun bu talab ancha yumshoq bo‘ldi va, asosan, yagona chastota rejasining mavjudligi bilan chegaralandi;
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toMiq optik tarmoqlar texnologiyalarida optik buferlarni yara- lish murakkab masalalardan biridir. Shuning uchun buferlash- tirishsiz kommutatsiyalash texnologiyasidan foydalanuvchi optik paketli kommutatorlarga afzallik berishadi;
yangi arxitekturalar har bir optik domenning o‘ziga xos xususiyatlarini hisobga olishi kerak, bu ulardan konstruksiyani soddalashtirish uchun foydali bo‘ladi.
Bundan keyin AON da paketli kommutatsiyaning ikki uslubi: ketma-ket bitli va parallel bitli paketlar kommutatsiyasini ko‘rib chiqamiz.
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uchraydigan moylash turlarining sxematik ifodasi

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uchraydigan moylash turlarining sxematik ifodasiBog'liq K. J. Matkarimov b. J. Mahmudov a. A. Norqulov avtomobillarda isuchraydigan moylash turlarining sxematik ifodasi.
Juda ham og‘ir ish sharoitlarida ishlaydigan uzellarda, masa
lan, gipoidli uzatmalarda quruq ishqalanish hosil bo‘lishi hisobiga
yemirilish va timalishlarning kelib chiqishiga to‘la barham beril-
magan. Tirnalishga qarshi qo‘llaniladigan usullarning eng sama-
ralisi moy tarkibiga tirnalishga qarshi qo‘shilmalar qo‘shishdir.
Tirnalishga qarshi qo‘shilmalarning ta’sir mexanizmi yemirilishga
qarshi qo‘shilmalar kabi bo‘lib, sirpanuvchi detal sirtida tirnalishga
qarshi moy pardasini hosil qiladi.
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Odatda, ishqalanishning bunday aralash rejimi mexanizmlarni
ishga tushirishda, yuklanish va ish harorati ortib ketganida, qo-
vushoqligi mos kelmaydigan moy ishlatilganida yoki ishqalanuv-
chi sirtlarga yetarli moy berilmaganida yuzaga keladi. Suyuqlikli
ishqalanish ko‘pincha moyga abraziv mexanik aralashmalar tush-
ganida buziladi. Suyuqlikli ishqalanish mexanizm, agregat, uzel-
ning barcha ish rejimlarida ta’minlanmaydigan hollarda moy par-
dasi qancha mustahkam bo‘lsa, detallar shuncha kam yeyiladi.
Moyning himoyalovchi xususiyatlari. Moylarning bu xususi-
yati transmissiya detallarining elektrokimyoviy yemirilishining ol-
dini olishi bilan baholanadi.
Amaliy kuzatishlarning ko‘rsatishicha, tarkibida korroziya in-
gibitorlari bo‘lmagan transmission moylar uzluksiz (uzoq muddat
to‘xtatmay) ishlatiladigan mashinalarning transmissiyasi detalla-
rini elektrokimyoviy korroziyadan himoyalash xususiyatiga ega.
Ishchi-himoyalovchi moylar, ya’ni tarkibida korroziya ingibitorlari
bo‘lgan moylar, mashina detallarini 3–5 yil va hatto 10 yil va un-
dan ham ortiq muddat ishlatilganida yoki saqlanganida himoyalash
xususiyatiga ega.
Transmission moylarga ularni kimyoviy aktivligi, adsorbsion
xossalari va termodinamik noturg‘unligini oshirish uchun ko‘p
miqdorda qo‘shilma va komponentlar qo‘shiladi. Moyning tarki-
bidagi qo‘shilmalar va komponentlar cho‘kib qolmasligi kerak va
moy asosi bilan fizikaviy turg‘un bo‘lgan aralashma hosil qilishi
lozim.
Agar moy tarkibiga quyultiruvchi polimer qo‘shilmalar qo‘shi-
ladigan bo‘lsa, bunda moy qovushoqligini kamaytirish qaytmas ja-
rayon bo‘lish ehtimoli borligini hisobga olish lozim.
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Mulkning saqlanishini ta'minlash funksiyasi

3. Mulkning saqlanishini ta'minlash funksiyasi. Bu funksiya buxgalteriya hisobi tizimini
takomillashtirish va uning nazorat funksiyasini kuchaytirish bilan chambarchas bog‘liq. Shuni alohida
ta'kidlash zarurki, ushbu funksiyani amalga oshirish uchun quyidagi shart-sharoitlar zarur: jihozlangan
omborxona binolari, nazorat va o‘lchash asboblari, o‘lchagich idishlar va boshqalar.
Inventarizatsiyaushbu funksiyani amalga oshirishning muhim usuli bo‘lib, korxona mulklarining
saqlanishi va ular tarkibida ro‘y beradigan o‘zgarishlarni aniqlashga imkon yaratadi. Uni amalga oshirish
uchun №19-«Inventarizatsiyani tashkil etish va o‘tkazish» nomli Buxgalteriya Hisobi Milliy Standarti
(BHMS) dan foydalaniladi. Ushbu standart O‘zbekiston Respublikasi «Buxgalteriya hisobi to‘g‘risida»gi
qonuning 11-moddasiga muvofiq ishlab chiqilgan.
Inventarizatsiya jarayonida barcha xo‘jalik muomalalari hujjatlar bilan rasmiylashtirilganligi va
tegishli buxgalteriya hisobi schotlarida aks ettirilganligi, zarur aniqliklar va tuzatishlar kiritilayotganligi,
hamda joriy hisob ko‘rsatkichlari va haqiqiy ma’lumotlarning o‘zaro mos (teng) kelishlari tekshiriladi.
Inventarizatsiya mahsulot ishlab chiqarish va realizatsiya qilishga qilingan xarajatlarni, mulklarni
saqlanishi maqsadida to‘g‘ri aks ettirish, asosan xom-ashyo va Materiallar va yoqilg‘i-enyergetik
resurslarning yo‘qotilishi borasida katta ahamiyatga ega. Chunki, bozor iqtisodiyotiga o‘tishning hozirgi
bosqichida va turli mulkchilik shakllari mavjudligi sharoitida inventarizatsiya o‘tkazish, odatda, katta
hajmdagi axborotlarga ishlov berish bilan bog‘liq. Shuning uchun inventarizatsiya o‘tkazish jarayonlarini
ham kompyutyerlashtirish zarur. Asosan katta nomenklaturadagi tovar-moddiy zaxiralarini inventarizatsiya
qilishda kompyutyerlardan foydalanish yuqori samara beradi.