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In our lab we want to simulate the information across a substation communication (TCP/IP) network and would also like to see the data packet information using Wireshark. I have used NetSim network simulator in the past but any tool is OK. Is there any literature on this?
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Can we model cyber attacks in such simulated power grid communication networks?
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I searched this in lot of sites but I was only abled to find out the ways of troubleshooting it.
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Are you trying to classify all the possible ways people might make mistakes in writing computer programs?
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In his name is the judge
Hi
for using matlab facilities especially matlab controller like fuzzy have to sending and receiving data between matlab and opensees, in fact i want send two data as fuzzy controller form opensees to matlab after each time history step in opensees and then matlab send back one output to opensees.
to achieve this i have to connect matlab and opensees with openfresco it means i do hybrid simulation.
first is this possible to do this?
second is there any one do work like this, do hybrid simulation generally or specifically do hybrid simulation between matlab and opensees. if yes i am very thankful to share work with me or for some aim.
have to say i prefer not to use openseespy and i almost read all example and guide in openfresco site and even on each site but i cant do this right.
Any help is greatly appreciated.
Take refuge in the right.
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dear Abolfazl Najafi thanks a lot for this suggestion
i think there is a lack time between opensees anb matlab run time it means when tcl try to write text file, matlab needs to read more data in text file and give error
after all i think working with python and openseespy library is the best choice for this goal.
wish you best
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Based on www.toda.network , the TODA protocol enables ledger-based blockchain to scale to billions of users with the near-zero cost for each transaction!
Now, who knows this ability on Industrial IoT networks in order to provide affordable solutions?
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Dear Elnaz Ashena,
Look over the following sources:
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Dear Researchers,
`Since I am new in the field of internet security, I need your suggestion regarding the meaning of the following features.
We have DNS google.com or youtube.com, and so on, and I want to extract different features based on Lexical and Web Scrapped.
Lexical Features:
what is the meaning of the following features? Please write with an example.
1) different ratios (different ratios (number to length, alphabet to length) ?
2) hash?
3) distance between a number to an alphabet? (You can find the meaning of these features in the paper Feature Extraction Approach to Unearth Domain Generating Algorithms (DGAs) - Page 401)
4) English domain name, not English yet pronounceable domain names, uni-gram?
Web Scrapping:
we extract information of the queried domain name from the web using Python (You can find the meaning of these features in the paper Feature Extraction Approach to Unearth Domain Generating Algorithms (DGAs) - Page 403)).
1) Levenshtein distance (sq1,se2), what is seq2?
2) Typosquat process?
Thanks
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you can use other artificial methods based on scripts that attempt to extract content from web pages HTML parsing
The use of web APIs causes complications due to robotic controls and access restrictions.
Good luck
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Hi, I have checked printed actual data and program version over TCP/IP on shell/command window. I want to communicate VDS with IPGMovie localhost on Simulink. There is VDS_GetData() function on vds-client-standalone.c , but I want to get RGB data on simulink.
I found TCP/IP Receive Simulink block, though I think I don't have much knowledge about TCP/IP .
-----------------------------------------------------------------------------------
I set parameters on TCP/IP Receive block as
Remote address: localhost
Port: 2210
Data Size: ?
Source Data type : ?
-----------------------------------------------------------------------------------
From IPGMovie.pdf guide..
RGB the data consists of width*height*3 ‘unsigned char’ elements
* Data Size: ?
If image size is 640x480, then is data size (640x480x3)?
Source Data type: ?
uint8?
Please give me your advice..
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cmcmd ('setprojectdir', PathToData);
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I'm curious to know if I can calculate the number of packets dropped when ethernet cable is configured as unidirectional and by pinging it from other end if we can calculate the delay, and packet loss
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Hi.,
There are a number of methods to avoid detection, one being configuring the ... Keywords: receive-only, cables, sniffing, network taps, uni-directional cables..
Refer this link:
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I need my ESP8266 to be an access point and command multiplexer to more devices. I need at 5 to 7 devices - 4 to 6 slaves and one master that sends them commands by TCP/IP and receives responses. I can't broadcast UDP, and commands must be sent to all nodes in less than 250ms.
The issue is that by default ESP8266 doesn't allow more than 4 connections. There are a compile-time variable max_connections set to 4. Some say that this limit can be set to 8, but ESP8266 won't support more sockets than 5. I'm here to ask: is there any way to surpass that limit? I have three possibilities on how to do that:
  1. Somehow configure ESP8266 that it can support more connections - perhaps it's just a question of reserved resources? Maybe somewhere in the firmware, there is another limit that can be changed? Disconnect one socket and connect another device in its place - will this be reliable?
  2. Use something else - but what? I need something small and fairly cheap. Other platforms I considered:
  • Arduino YUN - too big and quite expensive, unsure about the limit of clients
  • CC3000 - doesn't support AP mode
  • Onion Omega - unavailable and unsure about the limit of clients
  • Raspberry PI 3 - too expensive and too big
  • Raspberry PI Zero + WiFi dongle - PI Zero is unavailable below 10x it's official price
  • Intel Edison - verified it works, but is very expensive
  • Sparkfun Particle P0/P1 - not sure if AP mode is controllable and what is the limit of clients
I could do with a very small embedded router and an ESP8266 to control it - but can't find any such part either.
3. There is also one solution that I really don't want to do, but have considered it - stacking ESP's - I can do that, but this will be a very big hack and will make large problems with connecting devices to this monstrosity - must make more than one wifi network, will have to keep track how many devices are connected to each network etc.
Could you please tell me if #1 is possible? If not, any recommendations on #2?
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I didn't check in detail, but the limitation might stem from limitations in memory (RAM): the "mature" network stacks/protocols haven't exactly been designed with low resource consumption in mind.
Thus you may consider to use an ESP32: basically an ESP8266 "on steroids", it sports a dual-core microcontroller and significantly more memory at about the sme price.
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Hi community,
Good day to you. This is my first time working on TCP/IP communication in Simulink. To understand better, I am using the examples 'TargetToTargetTCPServer' on my laptop and 'TargetToTargetTCPClient' on my desktop. I had modified the IP address of my workstations to the addresses in the examples. However, when I try to run the simulation, the output status of the 'TCP configure' block is always zero. I am not sure if this is the problem in establishing TCP/IP communication between the client and server.
I tried searching for a solution for the past 2 days but couldn't find any. It would be really great if someone can help me with the issue.
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Hello,
I knew that MQTT works on TCP/IP network. But MQTT is application layer IoT protocol.
Whether it used all the functionalities of TCP or only some functionalities? If I want to verify that which functionalities of TCP it actually uses, how can I do that?
Need some guidance.
Regards,
Vishal
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Hi,
MQTT over TCP. The Message Management Service (MMS) supports native MQTT over TCP as a network transport method. For more information, please refer to theMQTT specification . To send data to the MMS through MQTT, a device needs toconnect to an MQTT broker and then send MQTT-compliant messages over this connection.
MQTT. MQTT (Message Queuing Telemetry Transport) is an ISO standard (ISO/IEC PRF 20922) publish-subscribe-based messaging protocol. It works on top of theTCP/IP protocol. ... MQTT-SN is a variation of the main protocol aimed at embedded devices on non-TCP/IP networks, such as Zigbee.
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Dear 'Named Data Networking' researchers,
As you know the current Vanilla NDN works over IP. If we assume that NDN architecture become the used Internet Architecture instead of TCP/IP, what will be the address of the final users (source of interest packet)? The physical address?!
In other words, does the interface in the FIB equal to physical address?
If not, for the case of wireless interfaces, we may have multiple users connecting through the same interface entry (university router for instance) How the address problem is solved when the data arrives back?
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In a non-local network context, each FIB entry contains a name prefix and a network interface (which represents a next hop). When running over IP, the network interface could be represented as an IP tunnel to the next hop.
In a local network, if NDN is running directly over link protocol (like Ethernet), then yes, the local FIB entry may contain a link protocol MAC addr.
Specifically, for wireless local network, researchers from Stony Brook University found there is no need for a per-host addr, so they are developing a name-based link layer protocol which focus on the data name instead of a per-host MAC addr.
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Hi,
I was looking for workable options available in NS-3 to use and modify light-weight implementation of the TCP/IP (LWIP) protocol suite. So far I have found network simulations cradle (https://www.nsnam.org/docs/models/html/tcp.html#network-simulation-cradle) installation as the only option but I can only see executable stacks for linux2.6.18 and linux2.6.26. There is no executable stack for lwip. I am also having a hard time finding any tutorial online on the usage of lwip in NS-3. 
Is there any way to execute lwip stack in NS-3? If not, does anyone know of any other light-weight tcp variant (with limited functionality and small footprint) that can be simulated in NS-3?
Kind Regards, Shahrukh 
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I highly recommend you to switch to OMNeT++ if you can. I was struggling to model some network with NS-3 for two weeks while I did it in OMNeT++ in two days.
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For Hikers/riders, they carry a GPS device which is connected to satellite and they can send messages to their family and friends ..
If I want to build a system to host all kinds of these devices and receive data from them related to their position.
WHAT kind of information or identification I need to know about these devices??
for example, for wireless or ethernet connection TCP/IP is the way to address .. what about the satellite devices ?
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Hi Acram,
My knowledge about GPS satellite tracking is based only on my personal experience. About 7 years ago (in the summer of 2012) me and around 10 my friends (scientists, journalists and crew members) were lost in the Chukchi Sea during an Arctic expedition. We were on the high-speed inflatable boat far away from the mother vessel (ESPY, GP). The main way of communication between the boat and the vessel was VHF marine radio. But it was completely useless, because we were around 30-40 miles away and the communication could not be established (the VHF capabilities is good for up to 10-15-20 miles depending on both antennas altitude). So the big problem was that we knew our GPS coordinates, but we didn't know the actual vessel coordinates to calculate our course and distance to salvation. We didn't even know the general direction where the vessel could be - is it North, South, East or West. We were completely lost...
And then a small device called "Yellow Brick" saves us (I believe it was some pre-version of this one: https://www.ybtracking.com/products-yb3). This small device has GPS receiver but also was capable to send and receive short emails (like SMS) to/from Inmarsat or Iridium satellites. So we on the lost boat could send email to the radio officer on the vessel and he could respond to us. This device also periodically sent the GPS coordinates by email to someone so he could constantly track your location.
In conclusion - depending on the desired geographic coverage and the application needs you should subscribe to a Satellite Communication Service. The major global providers are Inmarsat, Iridium and VSAT. If you don't need a global coverage then satellites on geostationary orbit could be used and may be the expenditure will be lower.
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Almost every properly configured commercial system will have only one TCP/IP port open to the Internet: Port 80.
Since this is the only way into the system, hackers will try many different ways to compromise it via this port. Surprisingly, there are only about 80 to 90 different hack queries in common use over the last 6 years, or so.
Commonly available IDS/IPS systems seem to only fall into one category, which keeps a blacklist of several hundred thousand malicious addresses, to which it refers every time a query appears on port 80. To stay current, the blacklist is updated every few days.
Since there are only about 80 distinct hack query formats, doesn't it make more sense to evaluate the threat by examining the query?
That's how we designed our IPS
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IPS = Intrusion Prevention System, stop any sort of intrusion before it happens
IDS = Intrusion Detection System, detect intrusions after they happen
The blacklist rules you are talking about would most often be implemented in a firewall (as it is usually the first appliance to see a request from the outside). Firewalls could technically be considered an Intrusion Prevention Device since it is preventing the outside requests from entering the network.
Common Intrusion Detection Services include honey-pots or internal network analysis tools. These tools are employed within a network to try to detect any bad behavior that has made its way past the firewall and other IPSs. Honey-pots are systems made to look like regular computers and offer up 'vulnerable' services that seem very enticing for hackers but everyday operations within the network will not interact with the honeypot. Once a hacker begins attacking the honey-pot the alarms will go off and the administrators will know that an intruder is in the network.
To answer your followup question: that specific botnet may have only used those 80 common queries but other botnets can(and probably will) use many other different queries. Telling your IPS system(firewall) to block those specific queries is a good start, but in order to battle more and more botnets you need to start thinking about the behavior and timing of the attacks as well as the source location of the attacks.
I would recommend looking up Bro and Snort for Intrusion Detection Systems, they are very powerful and opensource products that can be deployed on a raspberry pi or other compute device.
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Have you considered using a neural network model? I have a neural network model server. It gets its inputs from field measurements via modbus TCP/IP.
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updated bi-monthly
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TCP/IP has 4 layers while OSI has 7 layers.
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OSI was too generic and never really practical for networking equipment vendors, i believe. To understand this just take a modern application that runs over a network and try to identify which part of this application runs in each of the three top layers of the OSI model (session, presentation, application). It will be confusing. Instead the TCP/IP protocol suite combines these three layers into a single application layer. The bottom OSI layers (PHY, data-link, network, transport) are more easily comparable with the ones in TCP/IP suite (link (OSI PHY+data link), internet/IP (OSI network), transport/TCP/UDP but there are still some differences. TCP/IP is the protocol suite that the Internet and modern networks/inter-nets are using. Note also that TCP/IP predates OSI.
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Dear All--
In order to implement Modbus in my research related to power grid and smart grid environment as part of the energy sector, I am looking for a complete C++ open source code on Linux for Modbus TCP/IP version with full capability involving master and slave operation. I have tried so many sources but implementation was extremely difficult with lack of documentation. Awaiting to receive your feedback and help!
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Hi Ihab,
What kind of problems did you encountered ? Which sources did you try ?
Is there a reason not to use C ? I think the most complete lib is libmodbus on Github : https://github.com/stephane/libmodbus
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Would any know how to get a reliable open source Modbus TCP/IP C++ library? I have searched websites such a GitHub, CodePlex, Sourceforge, CodeForge, but i cant seem to find one written in C++. When i do come across Modbus TCP/IP C++ it has a price associated with it. If anyone has worked with a Modbus TCP/IP C++ open source library and can point me to the right direction where i might find it i would greatly appreciate it.
Sincerely,
Yuri Dobryansky
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What approaches exist to applying rate limits on a per-flow (TCP connection) basis? Could you elaborate on trade offs? Consider a datacenter environment with virtualization technologies and all layers (application, transport, etc.)
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Dear Mohammad Noormohammadpour,
this problem can be solved by the Congestion Control (CC) according to the concept ECN (Explicit Congestion Notification). The general concept of ECN was specified by the IETF in document RFC 3168.
The principle of ECN describes my article "ECN - Explicit Congestion Notification" (in German).
The section "Grundlegende Idee der Überlastvermeidung mit ECN --- Basic idea of overload avoidance with ECN, Pages 6 and 7" and Fig. 006175 are very important. Further figures 006176, ..., 006179 explain the concept ECN exactly.
CC according to ECN can be briefly summarized as follows (Fig., Pages 6 and 7):
  • When establishing a TCP connection, the two computers agree on the Window (W) parameter. The value of Window (from the target computer) tells the source computer how much data it can send without having to wait for a receipt from the target computer. Therefore, Window determines the maximum amount of data transmitted in one direction on a TCP connection that may be on the network at a time.
  • After receiving the packet indicating that the network is overloaded, computer A (source computer) halves the window size and signals this to the target computer B in the next IP packet sent to it. For this, he makes the "d" ( Fig. 006175) in the TCP header. If computer B has received the packet, the two computers have agreed that the window size has been reduced on the TCP connection between them.
Good luck and best regards
Anatol Badach
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Is it possible to connect multiple UAVs through IP and configure multiple routing protocols on it?and what would be the best wireless module for it.
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The case is that a vehicle needs to know the position of, let us say, other stationery ( I know it is strange, VANETs and Stationary doesn't usually fit  but that is the case) On Board Units (OBUs). To do that it geocast a query message and because it can't reach all the OBUs in the Geo region the message must be forwarded by near OBUs to further ones. Finally all the OBUs which received the message will return their position to the query initiator directly or to the direct message sender and so forth to reach the query initiator. As the the OBUs are stationary, the challenges ( fast connection, ... ) that face typical protocols doesn't exist here. What existing protocols built over the WAVE 802.11p MAC can be utilized to achieve that?       
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The Best networking protocol for vehicles are stationary is:
In standards for VANET (Safety applications) WSMP(Wave Short Message Protocol) is defined.
For Non safety application generally prefer IPv6
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I am on Linux platform with PostgreSQL 5.5. I am trying to monitor all traffic related to PostgreSQL between Master and Slave. To that end, I used Wireshark to monitor the traffic. Then, I started PostgreSQL and ran three queries (Create table Hello, Create table Bye & inserted an image to PostgreSQL database). During queries, I ran Wireshark on Master just to capture the traffic between Master and Slave.  
But there is one problems with PostgreSQL traffic captured using Wireshark. All the traffic is sent/received in TCP packets and that traffic is in coded form. I can't read that data. I want to find out all those three queries from Wirehsark that I inserted in PostgreSQL database. 
What is the best way to go about finding queries of PostgreSQL?
On the other hand, I ran same queries on MySQL database and repeated above mentioned experiment. I can easily read all those three queries in wireshark dump because they are not in coded form.
Wireshark file of PostgreSQL experiment is attached. I need to find out above three queries from Wirehsark. About File:
192.168.50.11 is the source machine from where I inserted queries to remote PostgreSQL's Master server. 192.168.50.12 is the IP of Master's server. 192.168.50.13 is the slave's IP address. Queries were executed from .11 and inserted into .12 and then replicated to .13 using Master-Slave approach. 
Pointers will be very welcome.
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Solution to my own problem:
I got the solution of my question.
I used Python code to insert queries into remote PostgreSQL database. I used following line in PostgreSQL to connect with database.
con = psycopg2.connect(host="192.168.50.12", database="postgres", user="postgres", password="faban")
If you use above approach then all the data will be sent in encrypted form. If you use the approach given below in python code then all the data will be sent in decrypted form. You can easily read all queries in Wireshark.
con = psycopg2.connect("host=192.168.50.12 dbname=postgres user=postgres password=faban sslmode=disable")
Same is the case in C-Code as well.
Decrypted data
sprintf(conninfo, "dbname=postgres hostaddr=192.168.50.12 user=postgres password=faban sslmode=disable");
Encrypted Data
sprintf(conninfo, "dbname=postgres hostaddr=192.168.50.12 user=postgres password=faban");
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Hi!
I am trying to implement a network very similar to the one that XBees create: with end devices, routers, etc. So I'm wondering if there are any devices that could act like that (specially the router mode is very important) but that they use Wi-Fi or other technology. I know there are XBee Wi-Fi but I want something different if possible.
Thank you in advance.
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ESP 8266 wifi.
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I am trying to build a mesh network of wireless sensors possibly with Telos motes. The intention is to build a network where nodes can communicate with the base station via other nodes. Has anyone build something like this? Any idea or advice is highly appreciated. Thanks.
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May you send me your email. I have some documents about this topic, You might find it interesting.
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Dear all, 
Does the 802.11n technology have a mechanism to keep track of the number of devices connected to it? Information regarding what it is called or what to specifically search for to read up more about this mechanism would be welcomed.
Thank you
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Yes of course. On a Linux based Access Point you can use tools like IW to get information about connected devices like number of transmitted/received bytes, signal strength, etc. See below an example output of my AP (wlan0 interface). Here you see the statistics for each associated client station (identified by their MAC address).
1/ Call: iw dev wlan0 station dump
Station 70:d4:f2:90:40:6e (on wlan0)
inactive time: 1530 ms
rx bytes: 2272
rx packets: 27
tx bytes: 2280
tx packets: 17
tx retries: 0
tx failed: 0
signal: -47 [-75, -47] dBm
signal avg: -48 [-77, -48] dBm
tx bitrate: 21.7 MBit/s MCS 2 short GI
rx bitrate: 2.0 MBit/s
authorized: yes
authenticated: yes
preamble: short
WMM/WME: yes
MFP: no
TDLS peer: no
Station 90:18:7c:dd:68:bf (on wlan0)
inactive time: 120 ms
rx bytes: 12583
rx packets: 239
tx bytes: 8702
tx packets: 64
tx retries: 0
tx failed: 0
signal: -46 [-65, -46] dBm
signal avg: -44 [-62, -44] dBm
tx bitrate: 57.8 MBit/s MCS 5 short GI
rx bitrate: 72.2 MBit/s MCS 7 short GI
authorized: yes
authenticated: yes
preamble: short
WMM/WME: yes
MFP: no
TDLS peer: no
On client side you can also get important information like the quality of the WiFi link, AP ESSID/BSSID, ...
2/ Call: iwinfo wlan0 info
wlan0 ESSID: "tplink18"
Access Point: 64:66:B3:CE:21:DB
Mode: Master Channel: 6 (2.437 GHz)
Tx-Power: 20 dBm Link Quality: 64/70
Signal: -46 dBm Noise: -95 dBm
Bit Rate: 39.7 MBit/s
Encryption: none
Type: nl80211 HW Mode(s): 802.11bgn
Hardware: unknown [Generic MAC80211]
TX power offset: unknown
Frequency offset: unknown
Supports VAPs: yes
Best,
Tolja
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I have just received the pCwori vector from a fellow researcher in research gate.  Unfortunately, there is no vector map available.  I was fail to find the vector map even in internet.  Million thanks in advance, if anyone could help.
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I would like to write a user subroutine that modifies the boundary conditions of a job at each increment, based on values it receives from a TCP/IP socket connection. The first problem/question is:
Can I write custom user subroutines for Abaqus other than the default ones or can I modify the UEXTERNALDB to call a "TCP/IP socket server module" to wait for data at a port, then use the data to modify the boundary conditions and then output the resulting displacement data as the response to the external client. The reason for this complexity is to allow me get this data as soon as it is ready instead of waiting for the files to be written to disk and accessing the obd.
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So I will answer this question now that I have solved the issue for anyone else requiring it. 
The DISP subroutine allows the user to modify the boundary conditions at the given nodes. The nodes have to be set to be user-defined in the model or if working with the input file (which I hate) then the boundary is specified as: 
*Boundary, user
This has to be done to use the DISP. It's a shame there is very poor documentation on ABAQUS subroutines and turorials for using them.
Next the UEXTERNALDB allows you access to the LOP variable which informs on when the subroutines are called. It should be used to know when to open references, files, connections. Typically LOP=0 is the start of an analysis or LOP=5 is the start of a restart analysis and these should be used to open the references/files/connections. LOP=6 should be used to close these references.
Next the external communication -  UEXTERNALDB gives the ability to write to file and read from the file by default but that functionality can be extended using an external winsock library which I found very useful (this library is ws2_32 which is part of the Visual Studio package so no need to add new modules. The initialisation, send, receive, closeconnection functions can be written in the same subroutine file as the DISP and UEXTERNALDB).
The winsock library allows me to open a connection to a server (at LOP=0) then feed current state of the system in real time at increment start to the server that replies with target boundary conditions that then feed to the DISP subroutine using common global variables.
This has been tested so far and it is fully functional and working. Have not got around to extracting current reaction forces yet with GETVRM or something similar but it should be easier to accomplish now. Hopefully, this gets someone through difficulties experienced.
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I had a glance on OSI layer and TCP/IP layer. But still confusion remains of not using two layers (presentation and session)
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Looking at delay attacks aginst Modbus TCP protocol, TCP/IP protocols as well attacks targeted at Master and field devices. Having difficulty locating detailed documents on these attacks..Any assistance or lead is much appreciated.
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i thinks timing delay in SCADA networks has to do with the complex digital to analog signal conversation. i.e from the digital circuitry to the  mechatronic automation system
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Hi there!
I want to receive accelerometer data which is sending over a tcp/ip connection in simulink. the problem is I can receive the data BUT they are meaningless. I think the problem is because the data format is in CSV files and they're "string" type. I solved this problem as script but I can't fix it in simulink. I really appreciate if anybody could help...
best regards
Amin Moosavi
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Hi Amin,
If you're running your simulation on a desktop you can make use of MATLABs string processing tools (like you would use in your script) by using the coder.extrinsic functionality, see link below.
Alternatively, if your model is compiled and coder.extrinsic won't work then you can user cover.ceval to call the standard C string processing tools such as sscanf. See second link below.
Finally, if neither of these work for you, you could write your own string to number parser, by using the fact that Simulink treats strings like an array of bytes with ASCII encoding (i.e. 49 = 1, 50 = 2, etc...). But this should only be a last resort!
I hope this helps,
Owen
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Hi, 
I want to run a stepper motor without using the software which is provided with the stepper motor vendors.
I want to send signal/command (Using Matlab) of the same format as it is send by the vendor software.
can anyone please suggest me. 
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You can perform remote debugging of your system with System Console. Debug equipment deployed in
the field through an existing TCP/IP connection. Run a network stack on either a Nios II processor or a
hard processor system (HPS) and piggyback on an existing remote administration setup. This application
note focuses on the case of using an Altera SoC.
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Surely, it is widely knows that TCP/IP satellite networks have a very high latency, specially for GEO links. However, which factors would be the most influent on the jitter for TCP/IP over satellite links ?
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You might want to take a look at these:
I don't know that jitter itself would be a big factor, but for sure latency is, at least for efficient use of TCP/IP. UDP, depending exactly how it is used, might not be impacted negatively. When using geosynchronous satellites, anyway, certain accommodations need to be made for the much longer RTT experienced, compared with terrestrial systems.
Another possible problem is your uplink speed. It might be very different from the downlink speed, which also impacts on TCP efficiency.
But I don't think jitter would necessarily be a problem particular to satellite.
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I'm looking forward to some documentation and/or manuals regarding on how E1/T1 circuits or any TDM phone carriers could be efficiently transported over IP networks.
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there are simple books from cisco, such as, DSL and Fiber-Optic Technologies. in the first chpters they talk about what you are asking for
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I am trying to applied a C++ software and a C software to readout data from a hardware module via gigabit-ethernet interface. This interface is embedded to PC's mother board via PCI-express.
The time for readout of C++ software is 4 times to 8 times slower than the C software. I really wonder where is the reason?
The header of C++ and C are the same (I checked this via tcpdump command of Linux).
I think the slow speed of C++ is caused by the overhead in tcp/ip connection .... I am thinking about some solutions ...
I hope for suggestions, comments from experienced people.
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I am not very proficient on GNU / LINUX C or C++ compilers, but for example, in old WIndows MS C/C++ compiler there was TWO libraries for TCP/IP (winsocks.h and wsock32.h) corresponding to GNU's sockets.h . Winsocks.h was an OLD version, and less effcient implementation of TCP/IP stack. May be your trouble has some relation with different "versions" of sockets.h 
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I was wondering at which layer the beacons are sent in VANET?
Usually vehicles broadcast their cooperative awareness messages aka beacons that contain current speed, location, time, heading, and so forth to the neighbor vehicles. Can these messages be implemented as application layer messages?
I need to work with the header information. More precisely I need to manipulate the header information (probably TCP or IP header) and use the offset information for my own purposes.
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beacon message used wireless short message (WSM) , it not used ip packet. MAC layer is responsible for broadcast. and the reason for using broadcasting mechanism because it don not require managing  routing and maintaing topology and address resolution. where these are challenging in VANET because of its high dynamic toplolgy
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Dear all,
I have a question (or actually a discussion) about networking, which we use to apply in a multi-channels experiment. 
I am working on SpaceWire technology for a network with 62 detection channels. However, I also wonder: why people have to think about SpaceWire networking? Why not just use the traditional TCP/IP networking? 
Some times, I think maybe SpaceWire is developed by FPGA technology, so it is more easy to change the function of the SpaceWire hardware just by programming. But is it true? If it's true, how about TCP/IP network? Can we make a TCP/IP network based on FPGA technology?
Thanks for spending your time on this discussion. This discussion is really helpful to a dummy as me.
Sincerely yours.
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I've developed network drivers for some of our SpaceWire products in the past.  The STAR-Dundee Brick and Router/Router Mk2 can be used on TCP/IP networks under Linux.  Very good for multiplayer gaming over SpaceWire :-)  There's no standard for transporting TCP/IP over SpaceWire, though, or for address resolution (SpaceWire to/from IP address), so our implementation probably won't work with other implementations.
Note that in the above case SpaceWire and Ethernet are being used in the same way.  The TCP/IP protocols are network and transport protocols running over these two physical layers.  SpaceWire provides a number of features which means it's not necessary to use additional protocols on top of SpaceWire, but that doesn't mean they can't still be used.
TCP/IP is very heavyweight for use onboard a spacecraft.  Networks on spacecraft tend to be reasonably small, using only one or two bus types, and encounter very few errors.  TCP/IP is designed to transport data between multiple networks, of different types, and with the possibility for packets to be lost, delivered out of sequence, or delivered with errors.  The minimum header size of a TCP/IP packet is 40 bytes, which is quite an overhead if you're sending small amounts of data, for example.
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By theory ,
It can be stated that UDP will faster as its connection less doesn’t required receiver side bothering,
but by my recent experiment I find TCP is some what giving 50% more throughput .
Theory which I formulated is, Overhead of TCP is one time. After that TCP get a connected way to pass data ,whereas UDP need to find it every time.
Also by Nagle effect which can make TCP packet immediate departure have same effect as UDP.
If so are ,then Why UDP is still in use in which condition UDP will be more useful then TCP.
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UDP and TCP are used in different situations for different applications. Applications requiring high reliability such as a 1GB file transfer are done by ftp using TCP. As now if  some packets are lost the whole 1GB transfer will be useless as it will end up in a corrupt file. UDP is unreliable and connection less which suits real time applications such as VOIP and streaming. Packet loss upto certain limit in these applications are not as critical as in a file transfer. Because even if a few packets are lost  you will fee glitches in your streaming or VOIP but still you will be able to run your video or voice.  Secondly TCP has many variants depending upon how they react to packet loss by controling its window size. You also need to consider that behavior when evaluating it. 
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Dear all,
I have a question about connecting via TCP/IP in a C++ software. I want to know the amount of data being transferred and received. Can anyone suggest for me some function ?
Before, I used the socket.h library, the return value of send() and recv() are useful. But now, I changed to another library developed by some institute..... If I changed this library I am afraid that I will change many consequences....
Thus, I want to check the transferred/received data without modifying the library or using send() and recv(). I mean a command/function to check directly? Or a algorithm to check. 
Thanks for reading and giving me suggestion.
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There are 2 commands that could help you. These are netstat and tcpdump. Check out the links in order to see how they are used.
Regards,
Andrés Miguel 
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I need to modify the congestion control algorithm in the MAC layer of IEEE 802.11- (WiFi) in a real world, hardware implementation. Does anyone know any developing tool that provides access to the code (and the necessary documentation), in that low layer of the TCP/IP stack?
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Depending on what you want to modify exactly, it could also be implemented in the device driver. I guess the unifying module for the WLAN MAC is mac80211 in Linux:
If it is not implemented there, I can definitely support the recommendation of Luis on OpenFWWF.
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I want multiple sessions to be open which capture different filters but the packets from different filters are processed by separate cores (slaves) and continous throughput should be returned to the master (where the master is a process assigning core).
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thanks alan it was a nice application......
i had build the mechanism in java but it is not real time...
so for my second task i will look forward with your sugestion
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Bufferbloat is a topic which has arisen recently. But a good simulation tool for "Bufferbloat" cases is not presented. The related keyword is TCP congestion control, TCP bottleneck simulation. If anybody has an idea of bufferbloat research and simulator, please share it with me.
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Well I never used Omnet++( as indicated in the topics), so I don't know specifically for Omnet. However, you could use ns-3 and increase the size of the parameters. The advantage is that you can inject real world traffic (i.e. traffic gennerators and traces), because ns-3 has mechanisms to handle real packets. Even more, if you use ns-3 + DCE, you can use real protocol implementations (linux + quagaa) and then change the parameters of those applications, what would be more realist than simple simulations.
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How to solve this problem:
SuperSocket Info: Bind failed on TCP port 1433.
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Hi,
This is usually the error that you get when there is either:
1)Another process/service listening on that port
2)You have a heavily utilized server
More info from Microsoft here:
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Why do some client terminal link to server, but IP refuse to change to that of server providing?
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Easy enough: StrongSwan