TCP stands for Transmission Control Protocol and is one of the core protocols of the Internet Protocol Suite. TCP complements the Internet Protocol (IP), and therefore the entire suite is commonly referred to as TCP/IP.

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1answer
52 views

What happens when I terminate a process and the socket send buffer is not empty?

In Windows (and probably in other operating systems), if a process has a TCP connection with another process on another machine, and then I terminate the process, an RST packet will be sent to the ...
0
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0answers
11 views

Determining whether a port is closed (no one is listening) or iptables reject my host

Can I tell whether the service I'm calling has a reject rule in its iptables or it doesn't listen on the port I'm calling? it seems that I always get icmp port unreachable
-2
votes
1answer
20 views

3 duplicate ACKs in TCP

If a client receives 3 duplicate ACKs in TCP then it will half the window size and switch from slow start to congestion avoidance. Will it retransmit the next window_size segments, or will it just ...
0
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1answer
18 views

Multiple TCP Connections to download simple webpage and images?

I created a very simple webpage: <html> <body> foo bar <img src="img1.png"/> <img src="img2.png"/> <img src="img3.png"/> Hello world </body> </html> And ...
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0answers
21 views

Buffering and accumation of packets send via TCP, setsocketopt is set in no delay mode, nagle is off [closed]

While creating the TCP socket we set the socket in TCP_NODELAY mode using the following code: if (!nagle) { int noDelay = 1; if ( ::setsockopt( m_clientSocket, IPPROTO_TCP, TCP_NODELAY, ( char* ...
0
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0answers
10 views

Check if ports are open for talking

I have a software (HP BSM) installed in a Windows server 2008 R2 Std This software needs to "talk" through a specific list of TCP ports and "listen" through other TCP ports. How can I know/check if ...
0
votes
1answer
25 views

Why is the FIN flag in TCP called FIN?

There are some flags in TCP. I already understand what other flag names come from, such as SYN stands for synchronization. I also know that FIN is used to close a connection. What I don't understand ...
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2answers
495 views

Force DNS resolution to use TCP

My Comcast internet connection has been giving problems in DNS resolution, and I am guessing the reason is a probably broken or limited UDP. I am currently working around it by tunneling over TCP ...
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9answers
2k views

How to make Firefox use TCP for DNS

I want to use TCP for DNS, to bypass my ISP's slow and broken DNS servers. I'm not using (and don't want to use) a proxy. Note: I want to use DNS over TCP because if I use it over udp, no matter what ...
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vote
5answers
9k views

Access Methods to a computer Using MAC Address

I have my own wifi network at home & recently when I checked the active clients on the wifi I found out the there is one active client. Router shows the MAC address of this client and I want to ...
1
vote
1answer
32 views

How to redirect TCP traffic from one virtual machine to another in Linux?

What is the simplest way to redirect all TCP traffic from one virtual machine to another in Ubuntu Linux and reverse? And what type of connection I suppose to use in VirtualBox?
0
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1answer
18 views

HTTP performance over high latency links

I have users that previously used FTP for file transfers across high latency paths to their local server. They have switched to HTTP for these transfers (not by choice) and file transfer perforamance ...
5
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2answers
8k views

For what does ssh use UDP?

Wile doing research I noticed that SSH both uses TCP and UDP. I completely understand the use of TCP, but UDP seems a bit strange. Why would I use an "unreliable" transport protocol with minimal ...
0
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0answers
29 views

Tunneling trough VPN over TCP

I'm currently trying to set up a VPN on my server to connect to from my Laptop. The server is a command-line ubuntu running on a x64 machine. The Laptop runs x64 Windows 7. The VPN itself is already ...
0
votes
1answer
16 views

How do you force linux to treat a tcp packet as if it were at the destination ip?

The situation: A tcp packet arrives on eth0 with destination 8.8.8.8. This packet meets some criteria that makes me want to intercept it (lets say I am interested in all packets from source ...
0
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0answers
34 views

RPC Connection Filtered with no Firewalls

I have a workstation (PC1) that cannot communicate with a domain controller over RPC (TCP/135). C:\PortQryV2> portqry.exe -n 192.168.1.1 -p tcp -o 135 Querying target system called: 192.168.1.1 ...
0
votes
1answer
14 views

Forward TCP packets by destination and port number

Is there any way to forward only TCP packets heading to destination XYZ and port number NN to 127.0.0.1 port number 9150 ? I'm on Windows. Thanks
0
votes
1answer
43 views

Receive encrypted string from server [closed]

What is the easiest way (as easy as possible) to make a web server that will check a string received from client and respond with another string? How to do it from the very beginning to the very end? ...
0
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0answers
29 views

Which congestion control algorithm is used by the TCP stack in OS X?

What congestion control algorithm is implemented in TCP in OSX 10.9? I would like to know if it uses NewReno, or something newer like Cubic in Linux.
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0answers
93 views

netsh set autotuninglevel: “the parameter is incorrect”

When trying to do netsh int tcp set global autotuninglevel=disabled from a command prompt, I get the error message "The parameter is incorrect". Several search results suggested "disabling 64-bit ...
1
vote
0answers
35 views

How to split pcap files maintaining tcp sessions

I have a pcap file which contains tcp traces. I was wondering if there's a way to split these traces in order to maintain tcp flows, but also filtering the traffic on a src ip basis. For example, if ...
2
votes
0answers
33 views

Force local packet pass trough the router (or disable loopback) - windows 8

i would like to avoid that packets sent from my machine to the same machine (via the IP assigned by the external router eg. 192.168.1.20) are routed with loopback and so never reach the external ...
0
votes
1answer
51 views

What is the timeframe used, for TCPBacklogDrop value calculation in netstat [closed]

I'm interested in the value TCPBacklogDrop of the command netstat -s on linux. But I don't know which timeframe is considered, when calculating it.
3
votes
1answer
207 views

Localhost tcp throughput performance differences

I have been using psping for measuring bandwith statistics on localhost on different computers: laptops, home computers and servers. All of them get to between 100 and 200 MB/s but my PowerPc at work ...
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votes
3answers
73 views

What happens when 2 hosts simultaneous establish a connection in a 3-way handshake

Say two hosts, A and B, both attempt to start a connection with each other, but the SYN from A gets to B before B's SYN arrives at A. My answer is that A would sent SYN ACK and would ignore the SYN ...
22
votes
4answers
54k views

What does “On-link” mean on the result of “route print” command?

I'm using Windows 7. When I type "route print" under command prompt, I get a IPv4 Route Table with several "On-link" values under the Gateway column. For example, like this one: IPv4 Route Table ...
0
votes
1answer
48 views

Testing DNS truncated queries over TCP with dig

I want to test if my network supports EDNS0. It means that if the record is bigger than 512byte, the DNS will be over TCP. It will ne truncated at firts using UDP ,the it willbe over tcp. I'm using ...
0
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1answer
46 views

Changing TCP sliding window behaviour

We all know that TCP's congestion control uses additive (linear) increase and multiplicative decrease when adjusting sliding window size. Is there a way to change it to "linear decrease"? When a ...
23
votes
3answers
9k views

How does Router know where to forward packet

If several computers with local addresses (192.168.0.#) are connected to a router and each computer opens a web browser and requests a page over HTTP, when these TCP:80 packets are sent out, the ...
0
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0answers
45 views

Cannot open port 25565 and others

I try to open my Minecraft server and my gmod server ports. Now I only try Minecraft and I tried to open in 192.168.1.1 in Windows firewall. I went to this site: ...
2
votes
1answer
44 views

Sending large data over TCP and progress indicators

It is my understanding that when you open a tcp connection to send data the tcp layer on the receiving end holds on to all the packet until the transmission is complete, then sends all the data up to ...
0
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0answers
38 views

Windows 7 stops responding to my SYN requests unless I continue to ping the client

Basic synopsis, my Windows 7 box stops sending RST, ACK packets to a client which is sending SYN packets after time. What I know: I have a client who sends a SYN packet, followed by a retransmit 3 ...
0
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1answer
40 views

How to determine which clients are connected to a specific port on a server [closed]

The network is Microsoft Windows but the server is running an unknown operating system. I cannot get access to a command line on the server. The server is running a custom protocol. The network ...
0
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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 ...
3
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2answers
8k views

How can I show only 127.0.0.1 traffic using Wireshark?

Every time I try to filter to just show a specific IP address, I get an error indicating that it is "not an interface or a field." I have no idea what that means. Furthermore, I don’t really see any ...
0
votes
1answer
35 views

Can I ping a host that has disabled the ICMP Ping option?

I need to know if it's possible to compare and test how fast is an IP (ie: any web or game server) relative to my location (in terms of network latency), even if they have disabled ICMP/Ping requests ...
1
vote
1answer
43 views

Different servers on the same port ipv4 / ipv6

Say I have two TCP servers A and B. A is an ipv4-only server listening on 127.0.0.1:10000. B is an ipv6-only server listening on ::1:10000. Can I start these on the same machine? That is, how are IP ...
0
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0answers
89 views

Retransmitted TCP packets (smaller than original) are being dropped, causes hang

I'm trying to troubleshoot my home internet connection, which often hangs on large downloads. I believe I have been able to duplicate the problem between my home computer and an Amazon EC2 instance ...
92
votes
13answers
9k views

Must TCP use IP?

Is it true that TCP is short for TCP/IP and they mean the same thing? Is it possible for TCP to be built on top of another protocol besides IP?
0
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1answer
49 views

TCP server listen and client listen windows software

I am using Windows OS on an amazon cloud AWS with static public IP. On this machine I need to set up a TCP server to listen on port 2204 for raw data that will arrive from a GPS base station over TCP ...
2
votes
1answer
6k views

Windows 7 firewall causing remote connection to time out; should refuse connection

The Windows 7 Firewall is running with default options to allow outbound connections and block incoming connections. I have a process trying to connect regularly from within my local network, which is ...
2
votes
2answers
4k views

Detect what outgoing ports are bypassed by firewall

My school has a firewall which limits most outgoing ports. There're only TCP/80, TCP/443, TCP/21 allowed. Is there's a way to find out all the outgoing port allowed by the firewall? My current idea: ...
0
votes
1answer
108 views

Forcing a game to not take “real local IP” into account but only recognize virtual local IP assigned by VPN server

We are two friends who want to play Heroes of Might and Magic 2, 3 or 5 together in online multiplayer mode over internet using a TCP/IP connection. As we are not happy with third party solutions ...
7
votes
5answers
2k views

How does a server get notified about the HTTP request?

I have a basic understanding of how HTTP works. I understand the client (web browser) makes a request and server responds back to the request. However, the thing I don't understand is how does a web ...
0
votes
0answers
26 views

Window Period Where Sent Packets Cause Socket Acting as Server to Malfunction

I am currently working on an embedded Linux server. My main application is a state-machine that is started during the init phase from the rc-scripts. The application spawns several worker threads. ...
0
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3answers
92 views

How does a web server return an HTTP request?

I'm sorry if this is a really stupid question; my networking knowledge is pretty sparse. So, a user makes a HTTP request to some address. That request comes from an address on a local subnet, but the ...
2
votes
4answers
12k views

Subnet mask of 255.255.255.255

I have a subnet mask of 255.255.255.255.( Why is my subnet mask 255.255.255.255?). I refer that from the above question that it is as good as each computer is on its own network and cant interact ...
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0answers
19 views

Assessing Performance in Process Explorer: Varying Block Sizes

I am trying to assess the performance of my scientific software using Process Explorer, with the files both locally on our blade server (Dell VRTx, Windows Server 2012) and over the network from ...
1
vote
1answer
98 views

Accessing two devices with the same IP?

I want to connect my laptop to two WiFi enabled digital cameras, that have the same IP hardcoded: 192.168.1.1 One solution that I've successfully tried: Connect one device to the laptop's built in ...
1
vote
1answer
185 views

Cannot connect to 192.168.1.1

I have router TP Link n900 and I cannot connect to my admin panel of the router, I just bought it, I have internet when I am connected with cabel, but cannot open the router. My connection is : PC -> ...