Transmission Control Protocol (TCP) and Internet Protocol (IP) provide end-to-end connectivity specifying how data should be formatted, addressed, transmitted, routed and received at the destination.

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Does TCP/IP model has 4 layers or 5 layers?

In some sites , It is given that tcp/ip has 4 layers,network access,internet,transport,application. But in some other references , it is given that it has 5 layers (instead of network access, physical ...
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326 views

Is it possible to have a Linux box with 2 Ethernet adapters, connected to 2 networks with same IP range (no routing needed)?

Bear with me. This relates to this Stack Overflow question. My Linux thing (actually a BeagleBoard) has two interfaces, eth0 and eth1. It needs to connect to a client's network on eth0 (address ...
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397 views

Network switch losing TCP packets between devices and a PC

I have a custom AVR microcontroller board that has a TCP/IP module (chip) for communication with PCs. My PC has a 4-port Gigabit Ethernet card. Each port is connected to an Ethernet switch HP ...
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74 views

Printing Over the Internet

I would like to know how to allow certain people, with unique user names, to be able to log in over the internet (not LAN) and be able to print their documents to my printer, which is connected to my ...
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2k views

Allow all inbound traffic from specific IP addresses

I am running one of our server applications on Windows 7 and I'm having trouble with the firewall. The application receives various events over TCP from a network device but the connection port varies ...
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77 views

How to inspect DSL router? [closed]

There is a DSL connection and a DSL router (Speedport W 701V). After some days or weeks (I didn't record the events) the router makes some problems. Internet connection is ... broken but not ...
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2answers
210 views

Monitor Application Network Activity

I use TCPlogView to see all tcp activity of a software. for example: An app (sample.exe) downloads this file in background: google.com/dl/sample.txt when I track it with a TCP software I see this: ...
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224 views

How are local ip addresses separated from public ones?

How does tools like ping, or any other tool that uses the tcp/ip protocol know that for example 192.168.1.1 or 10.0.0.1 is a local ip address while 8.8.8.8 or 74.142.23.95 are public? are 192.168.x.x ...
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Why don't outgoing TCP/IP connections need firewall ports to be opened?

While creating an incoming TCP/IP or UDP connection we need for a firewall port to be opened or to get privilege for the specified port. Why not for outgoing TCP/IP connections?
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1answer
653 views

Change TCP sequence numbers for packet replay?

First off, I'm using wireshark for capture and colasoft for replay. I'm attempting to replay a group of captured packets back, looped to be done several times over (the purpose of this is just to send ...
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3answers
829 views

How to monitor TCP connections over time

I have an application which is a windows service. It accesses a number of other services using TCP/IP. E.g. sql server databases, informix databases, mail servers, etc. For instance it will also ...
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2answers
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No ping response, still transmitting data [closed]

Why would a device with a static ip not respond to a ping, but still transmit information over the network? In my situation the device is a very simple caller ID box. It has no GUI. It's only purpose ...
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1answer
152 views

how to setup linux-igd to use webserver on same machine

So I have a web server on port 80 and linux-igd/upnp running on the same machine using dhcp. I want to configure linux-igd to be a way to get to the webserver. I found this tag in the linux-igd xml ...
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2answers
6k views

How to increase the TCP timeout on Windows 7?

For a test purpose, I would like to increase the default tcp timeout to say 2 mins. I tried this: How to set TCP/IP abort interval or timeout in Windows XP? http://support.microsoft.com/kb/170359 ...
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1answer
656 views

How do I prevent Linux kernel from responding to incoming TCP packets?

For my application, I need to intercept certain TCP/IP packets and route them to a different device over a custom communications link (not Ethernet). I need all the TCP control packets and the full ...
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1answer
4k views

Resetting TCP/IP Settings on Windows 8

Apparently, there's a command: netsh int ip reset which is known to reset TCP/IP settings for Windows XP/Vista/7 and I'm not sure how it works correctly on Windows 8. When I typed the command ...
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1answer
306 views

Down sides of lowering tcp time_wait value on windows server 2008

i am building an adserver. In tests i see lots of TIME_WAIT state due to the use of an in memory db redis. Forums suggested lowering the time wait value from registry. Any down sides ?
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1answer
107 views

Where'd my wireless go?

Got an old Lenovo R60e running XP Home that I use for misc. wireless tasks around the house. I had need to print from a fixed workstation to a USB printer in another room. So, I turned on printer ...
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1answer
70 views

Unable to query ports on windows network

I have 2 environments that need to speak with each other, 2 servers are sitting in our test environment and 1 is in our corp environment. Client A was setup over a year ago and works as expected, I ...
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1answer
1k views

Trouble getting VPN to work with my router, possible WPAD issue

I've been having a problem using Cisco Anyconnect VPN on Windows 7 with my wireless router (a Belkin F5D8635-4 v1 Wireless N). It connects sometimes, but often won't until the router has been reset. ...
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1answer
353 views

FTPS - Cant Open Data Connection over WAN

Here is my setup, 1 Windows 2008 R2 Standard Box /w G6 FTP Server installed G6 is configured to use explicit SSL connections only (TCP:990) 1 WatchGaurd Firebox Firewall (between server and internal ...
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2answers
1k views

Capture TCP communication on a specific port using wireshark

I have build a simple TCP server which listens on port 9999, and it has IP address 202.168.66.1. I have a TCP client which has the same IP address and connects to the server on the said port. Now ...
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How to know which Windows application does listen on a particular TCP port? [duplicate]

I have been using a personal HTTP proxy to remove ads and boost caching for a while but have then noticed that my Firefox still works when the proxy application is shut down (while the browser is ...
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2answers
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TCP header option: SACK-permitted (Selective Acknowledgments) negotiation

I'm doing a research project, which needs to split tcp connection. so I have some pecular questions, which may happen in my development. The problem is understanding of TCP SACK-permitted ...
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how tcp stack deal with the ack_seq number and seq number of tcp FIN/ACK packet?

from my knowledge, seq and ack_seq are processed by tcp stack independently. when a packet arrives with a inconsistent ack_seq number if: 1) the ack_seq number is obsolete(smaller than expected), ...
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Determining contributors to elapsed time during a network request

The situation: There is a remote server. I am running a client program that makes calls to the server and requests data. These requests perform very slowly. The server limits the number of results ...
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Tcpip error: Request failed due to all such ports being in use

Today my machine stopped being able to access the internet. I can still access some local network resources. When I looked in the error log I saw following tcpip warning: A request to allocate an ...
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3answers
205 views

How do I test network performance between server and smart-devices

I am currently working on a test use case where I need to test performance (benchmark) between a server/computer and smart-devices (tablet, smartphones etc.). The benchmark I want to do is based on ...
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2answers
841 views

TCP\IP Packet Signature - how to identify such data packets?

I know of a program that can "carve" (look for) TCP IP Packets from raw binary data. The results it presents are the source and destination MAC addresses, the source and destination IP addresses and a ...
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1answer
247 views

How does the browser know which packet is the response to a specific request?

I am sniffing the in/out packets over TCP. I have some GET output, but I want to know which of the packets is the input? How does the browser determine this? Simpler explaination: I'm sniffing and I ...
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1answer
4k views

Not able to ping remote server

I am getting Request Time Out on pinging a remote server. I am on my laptop connected to the this server via Remote Desktop Connection. tried but still not able to ping it. I just want to ellaborate ...
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638 views

DNS server keeps changing from Auto to Manual

A friend at a company I know has a fairly new Windows 7 laptop. She was complaining that the "internet doesn't work". After looking at it the first time, in Wireless > Status > Properties > ...
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Determining what process has bound a port (without listening) on Windows

If I want to find out what process is listening on what socket, I can use netstat/TCPview and will immediately see it. However, it is possible to bind to an address without listening. If this is done, ...
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How do I log outgoing TCP connections from my computer?

I'm trying to track down a problem where something is causing my active directory account to get locked out. I think that I could figure it out if I can log all connections to 2 specific servers. I ...
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Please get me outta here.. Stubborn APIPA

Any one please help me.. I am getting an APIPA since three days.. I did all the steps mentioned in answers to this question. Still they did not resolve my problem. At last I formatted whole of my ...
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1answer
116 views

Limiting upstream rates for web in Ubuntu 12.10

I found this thread, but am hesitant when it comes to screwing with my network settings. What I want to do is limit the rate that people can download files from my webserver remotely. LAN ...
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XP to Win 7 via ethernet cable. No routers, no wireless. They can't ping each other

I've got a windows XP machine and a windows 7 laptop connected by an ethernet cable. The xp has static ip address 169.254.84.221 and the windows 7 has 169.254.84.220. both subnet masks 255.255.255.0. ...
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Why are there limitations on TCP segment size?

I have a question about the limitations on the segment size in the transport layer. Since the data has to get to the lower layers why will it be fragmented? Finally the data is sent in bits at the ...
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502 views

Is there free software that can convert serial input messages to TCP/IP packets?

There is a serial port that can receive text messages from the external device. Now I want to pass these messages to a special software. But that software can only receive TCP/IP packet. For example, ...
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Is it possible to see content of TCP/IP connection?

This is a bit weird. I want to see the content of all TCP/IP connections coming in/out of the system. Is any of this possible on the same machine? I know I won't be able to see encrypted content but ...
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How to reset Host Only Adapter Networking for Oracle VirtualBox VM Manager

My Host Only Networking stopped working, how do I reset it ? I tried disabling and re-enabling Local Area Connection and VirtualBox Host-Only Network but VirtualBox Host-Only Network is still ...
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1answer
350 views

IP checksum offload

I recently updated to Windows 8 and get alot of invalid packet transfers. It says "Ip checksum offload?" (Wireshark) and most of my packets get lost. The checksum is 0x00. I also updated my NIC ...
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352 views

TCP-IP versus TCP-IP over VPN

What are the advantages and disadvantages of a TCP-IP connection over VPN opposed to a regular TCP-IP connection? I am interested mainly in speed and security! Thank you.
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645 views

No route to host after changing interface to static ip

I installed a Linux (Ubuntu) server inside my home LAN, initially it's automatically configured to use DHCP interface. I'm connecting to this server from another computer using that server's hostname. ...
3
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1answer
532 views

Change the default route without affecting existing TCP connections

Let's say I have two public network addresses on my server: one NAT through an ISP (192.168.99.0/24), and a VPN through a different ISP (192.168.1.0/24), already configured with a per-host route to ...
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1answer
117 views

How does the internet protocol handle network card numbers?

I know that data packets sent over the internet carry the source and destination IP address, so that the protocol can route the data to the correct destination and keep track of the source address of ...
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DHCP/routing oddness

I have a Squid proxy server on my network that is connected to the DHCPd server (commodity router) through a commodity switch. If there is a break in the connection (eg router needs to be rebooted) I ...
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2answers
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Are Segments, Packets and Frames the same size if we ignore headers?

I've looked for some explanation about the differences between Segments, Packets and Frames, and from what I read: Segment is the original data + Transport Layer header. Packet is a Segment + ...
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Service to transparently use an HTTP CONNECT proxy on Linux

As our corporate network provides an HTTP CONNECT proxy for people who need to connect to the outside world, and as every Linux application needs to be set up specially to use it, I was thinking about ...
3
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1answer
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User defined mapping hostname-to-address without root privileges

Is it possible to define a mapping hostname to IP address in Linux without root access (ie modify /etc/hosts) nor a DNS server ?