It is an IETF standardization initiative whose goal is to come out with an Internet standard Version of SSL. The presentation discusses all. Happy Learning. :)
It is an IETF standardization initiative whose goal is to come out with an Internet standard Version of SSL. The presentation discusses all. Happy Learning. :)
https://www.youtube.com/watch?v=lKrbeJ7-J98
HTTP messages are how data is exchanged between a server and a client. There are two types of messages: requests sent by the client to trigger an action on the server, and responses, the answer from the server.
This attack was made possible due to a programming vulnerability in OpenSSL libraries. The attack was discovered in 2014. It can help attackers steal very sensitive data like session Ids, cookies, etc.
https://www.youtube.com/watch?v=lKrbeJ7-J98
HTTP messages are how data is exchanged between a server and a client. There are two types of messages: requests sent by the client to trigger an action on the server, and responses, the answer from the server.
This attack was made possible due to a programming vulnerability in OpenSSL libraries. The attack was discovered in 2014. It can help attackers steal very sensitive data like session Ids, cookies, etc.
If the number of spine switches were to be merely doubled, the effect of a single switch failure is halved. With 8 spine switches, the effect of a single switch failure only causes a 12% reduction in available bandwidth. So, in modern data centers, people build networks with anywhere from 4 to 32 spine switches. With a leaf-spine network, every server on the network is exactly the same distance away from all other servers – three port hops, to be precise. The benefit of this architecture is that you can just add more spines and leaves as you expand the cluster and you don't have to do any recabling. Intuition Systems will also get more predictable latency between the nodes.
As a trend, disaggregation seems to be most useful for very large companies like Facebook and Google, or cloud providers. The technology does not necessarily have significant implications for small or medium sized businesses. Historically, however, technology has a way of trickling down from the pioneering phases of existing only within large companies with tremendous resources, to becoming more standardized across the board.
Network Address Port Translation. Residential Network connections vi.pdfshalins6
Network Address Port Translation. Residential Network connections via Cable or DSL usually
are allocated only a single IP Address. As end users often want to operate multiple internet
enabled devices at home, people often use small routers to map an internal network with multiple
IP addresses, to the single IP address provided by the ISP. This is referred to as Network Address
Port Translation (NAPT) or just Network Address Translation (NAT). Assume we have a home
network that is connected by a wireless router that includes NAT capabilities as well as a DHCP
server. On the wireless network we have a Desktop, a Laptop and a Video Game Console that
are switched on and used in this order. The external IP address of the router is 71.204.145.120,
the internal IP address is 192.168.1.1. The DHCP server on the router is programmed to give out
IP addresses on the nework 192.168.1.1, netmask FF:FF:00:00.
(a.) Draw the topology of the network with the router after all devices are switched on (you can
omit any hosts between the wireless router and myth18). The topology should include IP
addresses and netmasks where known.
(b.) After all three hosts on the wireless network are switched on they connect to a web server
running on myth18.stanford.edu. What IP addresses will the web server on myth18 record for the
web requests coming from the Laptop, Desktop and Video Game Console?
(c.) Both the Laptop and Desktop have an SSH server running on port 22. Is it possible to
connect from myth18 to the SSH servers? If yes, explain the steps involved in setting up the
connection. If no explain why it is not possible.
(d.) Is there an upper limit for the maximum number of parallel UDP connections from hosts on
the local network of the router to servers on the internet? If yes, what is this maximum?
Solution
A single listening port can accept more than one connection simultaneously.
There is a \'64K\' limit that is often cited, but that is per client per server port, and needs
clarifying.
Each TCP/IP packet has basically four fields for addressing; these are:
Inside the TCP stack, these four fields are used as a compound key to match up packets to
connections (e.g. file descriptors).
If a client has many connections to the same port on the same destination, then three of those
fields will be the same - only source_port varies to differentiate the different connections. Ports
are 16-bit numbers, therefore the maximum number of connections any given client can have to
any given host port is 64K.
However, multiple clients can each have up to 64K connections to some server\'s port, and if the
server has multiple ports or either is multi-homed then you can multiply that further.
So the real limit is file descriptors. Each individual socket connection is given a file descriptor,
so the limit is really the number of file descriptors that the system has been configured to allow
and resources to handle. The maximum limit is typically up over 300K, but is configurable e.g.
wit.
A brief explanation of how the web request works. The smooth process can be hard to understand at first, but as you go through the slide it will become more clearer than earlier.
Similar to Wireshark Lab HTTP, DNS and ARP v7 solution (20)
Cloud computing is defined as a computer model that enables fast and with minimal effort the access, which is made on demand, from a network to a common storage computing resources.
Secure Electronic Transaction
Contents are:
Secure Electronic Transaction
SET Business Requirements
SET Protocols
Parties in SET
Implementation of SET
SET Transaction
Dual Signature in SET
Dual Signature Operation
SET Supported Transaction
Credit Card Protocols
Contents:
Introduction
Architecture
MAC Sublayer
Distribution Coordination Function
Point Coordination Function
MAC Layer Frame
Physical Layer
IEEE 802.11 FHSS
IEEE 802.11 DSSS
IEEE 802.11 Infrared
Contents:
Introduction to SONET
SONET/SDH Rates
SONET Layers Compared with OSI Model
SONET Architecture
SONET Frames
SONET Network Types
Advantages of SONET
Disadvantages of SONET
The purpose of types:
To define what the program should do.
e.g. read an array of integers and return a double
To guarantee that the program is meaningful.
that it does not add a string to an integer
that variables are declared before they are used
To document the programmer's intentions.
better than comments, which are not checked by the compiler
To optimize the use of hardware.
reserve the minimal amount of memory, but not more
use the most appropriate machine instructions.
Describe the process of coding, testing, and converting an organizational information system and outline the deliverables and outcomes of the process.
Prepare a test plan for an information system.
Apply four installation strategies: direct, parallel, single-location, and phased installation.
List the deliverables for documenting the system and for training and supporting users.
Distinguish between system and user documentation and determine which types of documentation are necessary for a given information system.
Compare the many modes available for organizational information system training, including self-training and electronic performance support systems.
Discuss the issues of providing support for end-users.
Explain why system implementation sometimes fails.
Describe the threats to system security and remedies that can be applied.
Show how traditional implementation issues apply to electronic commerce applications.
This chapter shows how to use knowledge about the wlorld to make decisions even when the
outcomes of an action are uncertain and the rewards for acting might not be reaped until many
actions have passed. The main points are as follows:
e Sequential decision problems in uncertain envirsinments,also called Markov decision
processes, or MDPs, are defined by a transition model specifying the probabilistic
outcomes of actions and a reward function specifying the reward in each state.
o The utility of a state sequence is the sum of all the rewards over the sequence, possibly
discounted over time. The solution of an MDP is a policy that associates a decision
with every state that the agent might reach. An optimal policy maximizes the utility of
the state sequences encountered when it is execut~ed.
e The utility of a state is the expected utility of the state sequences encountered when
an optimal policy is executed, starting in that state. The value iteration algorithm for
solving MDPs works by iteratively solving the equations relating the utilities of each
state to that of its neighbors.
Policy iteration alternates between calculating the utilities of states under the current
policy and improving the current policy with respect to the current utilities.
* Partially observable MDPs, or POMDPs, are much more difficult to solve than are
MDPs. They can be solved by conversion to an MDP in the continuous space of belief
states. Optimal behavior in POMDPs includes information gathering to reduce uncertainty and therefore make better decisions in the fiuture.
A decision-theoretic agent can be constructed for POMDP environments. The agent
uses a dynamic decision network to represent the transition and observation models,
to update its belief state, and to project forward possible action sequences.
Game theory describes rational behavior for agents in situations where multiple agents
interact simultaneously. Solutions of games are Nash equilibria-strategy profiles in
which no agent has an incentive to deviate from the specified strategy.
Mechanism design can be used to set the rules by which agents will interact, in order
to maximize some global utility through the operation of individually rational agents.
Sometimes, mechanisms exist that achieve this goal without requiring each agent to
consider the choices made by other agents.
We shall return to the world of MDPs and POMDP in Chapter 21, when we study reinforcement learning methods that allow an agent to improve its behavior from experience in sequential, uncertain environments.
Students, digital devices and success - Andreas Schleicher - 27 May 2024..pptxEduSkills OECD
Andreas Schleicher presents at the OECD webinar ‘Digital devices in schools: detrimental distraction or secret to success?’ on 27 May 2024. The presentation was based on findings from PISA 2022 results and the webinar helped launch the PISA in Focus ‘Managing screen time: How to protect and equip students against distraction’ https://www.oecd-ilibrary.org/education/managing-screen-time_7c225af4-en and the OECD Education Policy Perspective ‘Students, digital devices and success’ can be found here - https://oe.cd/il/5yV
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
How to Split Bills in the Odoo 17 POS ModuleCeline George
Bills have a main role in point of sale procedure. It will help to track sales, handling payments and giving receipts to customers. Bill splitting also has an important role in POS. For example, If some friends come together for dinner and if they want to divide the bill then it is possible by POS bill splitting. This slide will show how to split bills in odoo 17 POS.
The Art Pastor's Guide to Sabbath | Steve ThomasonSteve Thomason
What is the purpose of the Sabbath Law in the Torah. It is interesting to compare how the context of the law shifts from Exodus to Deuteronomy. Who gets to rest, and why?
Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
How to Create Map Views in the Odoo 17 ERPCeline George
The map views are useful for providing a geographical representation of data. They allow users to visualize and analyze the data in a more intuitive manner.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
The French Revolution Class 9 Study Material pdf free download
Wireshark Lab HTTP, DNS and ARP v7 solution
1. Wireshark Lab HTTP, DNS, ARP v7
HTTP
1. Is your browser running HTTP version 1.0 or 1.1? What version of HTTP is the server running?
Answer: Both are HTTP 1.1
2. What languages (if any) does your browser indicate that it can accept to the server?
Answer: Accept-Language: en-us, en
3. What is the IP address of your computer? Of the gaia.cs.umass.edu server?
Answer: My IP address is 192.168.1.102 and the server’s is 128.119.245.12
4. What is the status code returned from the server to your browser?
Answer: HTTP/1.1 200 OK (text/html)
5. When was the HTML file that you are retrieving last modified at the server?
Answer: Last-Modified: Thu, 07 Jun 2007 22:09:01 GMT
6. How many bytes of content are being returned to your browser?
Answer: Content-Length: 126
7. By inspecting the raw data in the packet content window, do you see any headers within the
data that are not displayed in the packet-listing window? If so, name one.
Answer: No all of the headers can be found in the raw data.
8. Inspect the contents of the first HTTP GET request from your browser to the server. Do you
see an “IF-MODIFIED-SINCE” line in the HTTP GET?
Answer: No
2. 9. Inspect the contents of the server response. Did the server explicitly return the contents of the
file? How can you tell?
Answer: Yes because we can see the contents in the Line-based text data field.
10. Now inspect the contents of the second HTTP GET request from your browser to the server.
Do you see an “IF-MODIFIED-SINCE:” line in the HTTP GET? If so, what information follows
the “IF-MODIFIED-SINCE:” header?
Answer: Yes. The information following is: Thu, 07 Jun 2007 16:29:01 GMT.
11. What is the HTTP status code and phrase returned from the server in response to this second
HTTP GET? Did the server explicitly return the contents of the file? Explain.
Answer: is HTTP/1.1 304 Not Modified. The server didn’t return the contents of the file since the
browser loaded it from its cache.
12. How many HTTP GET request messages were sent by your browser?
Answer: There was 1 HTTP GET request message sent by my browser as seen in the screenshot.
13. How many data-containing TCP segments were needed to carry the single HTTP response?
Answer: TCP segments containing 309, 1452, 1452, 1452 and 144 bytes respectively for a total
of 4500 bytes.
14. What is the status code and phrase associated with the response to the HTTP GET request?
Answer: 200 OK
15. Are there any HTTP status lines in the transmitted data associated with a TCP induced
“Continuation”?
Answer: No
3. 16. How many HTTP GET request messages were sent by your browser? To which Internet
addresses were these GET requests sent?
Answer: As you can see from the above screenshot there were 3 HTTP GET requests sent to the
following Internet addresses:
a. 128.119.245.12
b. 128.119.240.90
c. 165.193.123.218
17. Can you tell whether your browser downloaded the two images serially, or whether they were
downloaded from the two web sites in parallel? Explain.
Answer: By checking the TCP ports we can see if our files were downloaded serially or in parallel.
In this case the 2 images were transmitted over 2 TCP connections therefore they were
downloaded serially.
18. What is the server’s response (status code and phrase) in response to the initial HTTP GET
message from your browser?
Answer: Status code: 401, Phrase: Authorization Required
19. When your browser’s sends the HTTP GET message for the second time, what new field is
included in the HTTP GET message?
Answer: As seen in the screenshot the new field (highlighted) is Authorization.
Authorization: Basic d2lyZXNoYXJrLXN0dWRlbnRzOm5ldHdvcms=rn
DNS
4. 4. Locate the DNS query and response messages. Are then sent over UDP or TCP? ANSWER:
They are sent over UDP
5. What is the destination port for the DNS query message? What is the source port of DNS
response message?
ANSWER: The destination port for the DNS query is 53 and the source port of
the DNS response is 53.
6. To what IP address is the DNS query message sent? Use ipconfig to determine the IP address
of your local DNS server. Are these two IP addresses the same?
ANSWER: It’s sent to 192.168.1.1,
7. Examine the DNS query message. What “Type” of DNS query is it? Does the query message
contain any “answers”?
ANSWER: It’s a type A Standard Query and it doesn’t contain any answers.
8. Examine the DNS response message. How many “answers” are provided? What do each of
these answers contain?
ANSWER: There were 2 answers containing information about the name of the host, the type of
address, class, the TTL, the data length and the IP address.
9. Consider the subsequent TCP SYN packet sent by your host. Does the destination IP address
of the SYN packet correspond to any of the IP addresses provided in the DNS response message?
ANSWER: The first SYN packet was sent to 209.173.57.180 which corresponds to the first IP
address provided in the DNS response message.
10. This web page contains images. Before retrieving each image, does your host issue new DNS
queries?
5. ANSWER: No
ARP
1. What is the 48-bit Ethernet address of your computer?
ANSWER: The Ethernet address of my computer is 00:09:5b:61:8e:6d
2. What is the 48-bit destination address in the Ethernet frame? Is this the Ethernet address of
gaia.cs.umass.edu? What device has this as its Ethernet address?
ANSWER: The destination address 00:0c:41:45:90:a8 is not the Ethernet address of
gaia.cs.umass.edu. It is the address of my Linksys router.
3. Give the hexadecimal value for the two-byte Frame type field. What do the bit(s) whose value
is 1 mean within the flag field?
ANSWER: The hex value for the Frame type field is 0x0800.
4. How many bytes from the very start of the Ethernet frame does the ASCII “G” in
“GET” appear in the Ethernet frame?
ANSWER: The ASCII “G” appears 52 bytes from the start of the ethernet frame. There are 14 B
Ethernet frame, and then 20 bytes of IP header followed by 20 bytes of TCP header before the
HTTP data is encountered.
5. What is the hexadecimal value of the CRC field in this Ethernet frame?
ANSWER: The hex value for the CRC field is 0x 0d0a 0d0a.
6. What is the value of the Ethernet source address? Is this the address of your computer, or of
gaia.cs.umass.edu? What device has this as its Ethernet address?
6. ANSWER: The source address 00:0c:41:45:90:a8. Ethernet address of gaia.cs.umass.edu not the
address of my computer. It is the address of my Linksys router.
7. What is the destination address in the Ethernet frame? Is this the Ethernet address of your
computer?
ANSWER: The destination address 00:09:5b:61:8e:6d is the address of computer.
8. Give the hexadecimal value for the two-byte Frame type field. What do the bit(s) whose value
is 1 mean within the flag field?
ANSWER: The hex value for the Frame type field is 0x0800.
9. How many bytes from the very start of the Ethernet frame does the ASCII “O” in “OK” (i.e.,
the HTTP response code) appear in the Ethernet frame?
ANSWER: The ASCII “O” appears 52 bytes from the start of the ethernet frame.
10. What is the hexadecimal value of the CRC field in this Ethernet frame?
ANSWER: The hex value for the CRC field is 0x 0d0a 0d0a.
11. Write down the contents of your computer’s ARP cache. What is the meaning of each column
value?
ANSWER: The Internet Address column contains the IP address, the Physical Address column
contains the MAC address, and the type indicates the protocol type.
12. What are the hexadecimal values for the source and destination addresses in the Ethernet frame
containing the ARP request message?
ANSWER: The hex value for the source address is 00:d0:59:a9:3d:68. The hex value for the
destination address is ff:ff:ff:ff:ff:ff, the broadcast address.
7. 13. Give the hexadecimal value for the two-byte Ethernet Frame type field. What do the bit(s)
whose value is 1 mean within the flag field?
ANSWER: The hex value for the Ethernet Frame type field is 0x0806, for ARP.
14. Download the ARP specification from ftp://ftp.rfc-editor.org/innotes/std/std37.txt. A
readable, detailed discussion of ARP is also at http://www.erg.abdn.ac.uk/users/gorry/course/inet-
pages/arp.html.
a) How many bytes from the very beginning of the Ethernet frame does the ARP opcode field
begin?
ANSWER: 20 bytes.
b) What is the value of the opcode field within the ARP-payload part of the Ethernet frame in
which an ARP request is made?
ANSWER: ARP-payload of the request is 0x0001.
c) Does the ARP message contain the IP address of the sender?
ANSWER: Yes, the ARP message containing the IP address 192.168.1.105 for the sender.
d) Where in the ARP request does the “question” appear – the Ethernet address of the machine
whose corresponding IP address is being queried?
ANSWER:
15. Now find the ARP reply that was sent in response to the ARP request.
a) How many bytes from the very beginning of the Ethernet frame does the ARP opcode field
begin?
ANSWER: 20 bytes.
8. b) What is the value of the opcode field within the ARP-payload part of the Ethernet frame in
which an ARP response is made?
ANSWER: The ARP-payload of the request is 0x0002, for reply.
c) Where in the ARP message does the “answer” to the earlier ARP request appear – the IP address
of the machine having the Ethernet address whose corresponding IP address is being queried?
ANSWER:
16. What are the hexadecimal values for the source and destination addresses in the
Ethernet frame containing the ARP reply message?
ANSWER: The source address is 00:06:25:da:af:73 and for the destination is 00:d0:59:a9:3d:68.