Questions tagged [tcpip]

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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need to debug a wifi routing situation

I have a Movistar (spanish) router. I connect 3 items to it, using wifi, same SSID = "a22" a PC, ip = 192.168.1.54 a Raspberry, ip = 192.168.1.200 a Frontius inverter, ip = 192.168.1.78 ...
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how to change my IP address to another country? [duplicate]

I need to access that website which is allowed to be accessed from Syria. I have tried to change my IP address to make my device as Syrian device. however my attempt went wrong. here are my steps: I ...
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Why does Windows resolve all IPs of all NICs with the hostname?

I´m having diferents problems with TCP/IP aplications that works through HOSTNAME. The Server where this aplications are installed(WIN Server 2012) have 4 NICs and Windows,resolve his own hostname ...
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How do computers know how to use TCP

I'm asking from a Windows perspective but any perspective is great. Are NICs all a computer needs to interface with TCP? Wouldn't they also need some sort of software associated with TCP, or is that ...
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VM can access internet despite iptables DROP rules

I have installed VirtualBox and I have 2 Ubuntu VMs running on VirtualBox. Please see the network diagram: VM 1 (Client VM) has static IP address of 10.0.2.2. Gateway VM has 2 IP addresses - 10.0.2.1 ...
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How can I restore default settings and metrics in Windows Server 2019?

I have a Server 2019. With RAS installed and I have three NICs. I played around with the standard gateways to connect an IIS to the second NIC. Now I want to reset all routing and metric changes to ...
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A Dos attack possibilty using IP Datagram and TTL

So I recently learned about the whole IP Datagram and its headers. We learned about the TTL field that exists because sometimes a packet from a certain network id will be sent to another router, but ...
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network bridge query with hamachi?

I have an embedded hardware in one city connected with my mac laptop via ethernet. I wish to connect that hardware to the server in a different city. The server is not on the internet but I have a ...
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Address of a Transport layer?

In TCP/IP protocol stack following protocol level addresses exists: Data Link layer - MAC address Network layer - IP address Transport layer - ? Application layer - Socket address which is ...
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MAC address in TCP Header - HTTP Request?

In the same below, why are there MAC addresses in the respected request packets? Why and how did the client obtain the destination MAC address? At first I thought it was the router, but can this ...
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How to resolve VLAN tagging issues with Google Nest WiFi router

I am a software engineer and have some training and experience with TCP/IP networks, but not enough to figure out this intractable issue that appears to be caused by my choice of router colliding with ...
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Scenario where DHCP static lease AND static IP (both with same IP) on same machine?

OK the obvious answer is that "this is stupid", but please read the scenario. Let say, we have a very sensitive piece of equipment (like an alarm system), that we want to eliminate as many ...
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is "Empty reply from server" a deliberate reply, or a default one from the TCP/IP stack?

I have a device whose port 80 is open and I was wondering what is behind: ~ # curl -v http://192.168.10.253 root@srv * ...
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What is a (sub)network in the context of TCP/IP stack?

In the context of TCP/IP stack (that is the Internet), is a (sub)network defined as IP address + mask? If not, then how is a (sub)network defined? Clarificaltion: Given a complex interconnection of ...
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How to connect to HW device on IP address ending with .255?

I have HW device with web settings interface (similar principle like router, but it isn't router) and I changed the IP address of the device to .255. I know it is an broadcast address now and I'm ...
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When will the router remove an entry from its NAT table?

When will the router remove an entry from its NAT (net address translation) table? Most routers used in our homes maintain a NAT table to translate the public IP and port to the private ones. This is ...
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How to diagnose issue with browsing websites?

I've had an issue with my PC which started yesterday. After reboot it works fine for about 10 minutes, then i'm unable to browse any websites from Firefox, Chrome or Edge. Rebooting again fixes it for ...
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Connect adb wifi without using tcpip android

I am using nokia 5.1 plus amd my computer is Dell lattitude E6430 ETG model I'm using adb wifi and running it through cmd to run my application in mobile without using cable. I'm doing all these ...
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Windows 10 Data Usage Not Showing Up Properly

When I try to check my data usage in Windows 10 (ms-settings:datausage) my data usage doesn't show up. On the main screen it says 0MB. When I click "View usage by app" to get more detailed information ...
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Tool to send TCP RST flag

Since yesterday, we have strange traffic to our server that is causing it to consume up all memory over time. This is the pattern: time (sec) info ...
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How do Flow Control and Congestion control work together?

I am trying to learn about Flow Control and Congestion Control in TCP. So far I understand that flow control uses the sliding window method and the receiver advertises a receive window based on how ...
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How is network congestion detected in TCP?

I am trying to learn about Congestion Control in TCP and in this video (at 1:56), he says if there is no ack received, it assumes network congestion and cuts back the cwnd, no where he mentions about ...
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How to disable Path MTU Discovery on Windows 10

How can I disable Path MTU Discovery on Windows 10? Following these instructions for an older Windows version, I tried adding the EnablePMTUDiscovery registry value to HKEY_LOCAL_MACHINE\SYSTEM\...
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Is an open port on Router a threat if it's forwarded to a host which not exist

Consider we have port 65434 open on router (open for WAN). The port forwarding is done to a host which does not exist. Can a hacker exploit this open port on router which leads nowhere?
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Will the MS Windows RDP connection be a security threat if

I have read a lot regarding this subject, but still not much is clear. So the question is: will it be dangerous to use RDP for connections outside LAN if?: I have a special module which have ...
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How does port triggering know what ports to open?

Port Forwarding as I understand it When creating a port forwarding rule, the router keeps the specified external port open at all times, and simply forwards all inbound traffic for that port to the ...
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What is corel doing on my udp connections for Chrome?

I have a weird mc.corel.com address lingering in Chrome and some parts of svchost processes, what is going on?
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How these two TCP and IP work together?

I am not able to understand TCP/IP model where in layer 4 it says suppose using TCP means connection is oriented and packets will follow certain path but in layer 3 it says IP is connectionless and ...
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UDP between A and B only works if B sends packet first

I have two separate linux computers, A and B, that need to communicate via UDP on port 3000. They are each behind a different router, and I have port forwarding rules set up on each router. For some ...
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What if I spoof the MAC Address of a public device (such as a router)?

MAC addreess should be unique in a particular network. Manufacturers try to keep this unique, but there is no guarantee. Even we can create a virtual device using software. My question is, what will ...
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Router admin page not reachable through WAN port

Let us say , I have a home router which have LAN port : 192.168.0.1 WAN port : 10.137.141.195 Now , When I do 192.1768.0.1:80 , I am able to open the admin page but when I do 10.137.141.195:80 , I ...
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What does it mean to have a subnet mask /32?

I see in this question, the routing table has: 192.168.1.1/32 link#4 UCS 2 0 en0 openwrt.lan 46:94:fc:63:fc:7 UHLWIir 11 3610 en0 1200 ...
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Why is the local address the same as the peer one?

A weird issue occurred while I was troubleshooting with ss, the local address is exactly same as the peer one. Same IP address is ok, but how to explain the same port?
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Client cannot receive server Retransmission on a Windows 7 client and Windows 7 server setup

I have a Windows 7 server and a Windows 7 client application where the client application sends a query to the server application and the server application would respond. An issue can occur if the ...
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No-IP (Public IP) is painfully slow compared to direct IP address access

So I was making a software that sends screen image continuously using VB.NET (TCP) and when I type in my local IP address it sends screen image really fast but when I changed it into my public IP ...
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Connection failed error for client connected to server over wifi (TCP socket program in c)

Requirement : Need to send and receive message from two devices connected over wifi using TCP socket programming in c. Receiving connection failed for client socket. I am able to connect same client ...
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What's the fastest way to open TCP/IPv4 Properties? in Windows 10

Is there a shortcut to open TCP/IPv4 properties directly I go this way ⊞ win+R ncpa.cpl Click Ethernet Properties Scroll down to TCP/IPv4 and click it Too many steps Assume it's for a PC with a ...
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Multiple connections on same port using netconn

Trying to develop a MODBUS Slave application via STM32H743BI using LwIP 2.0.3 and FreeRTOS 9.0.0 My app should be able to handle multiple clients simultaneously. I want to create seperate threads for ...
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Is it possible to use FTP without filesystem in client?

Is it possible to use FTP protocol (not TFTP) to get file from ftp server to ftp client without using filesystem in client ? EDIT: The motives behind the question: I know that tftp can do it, but ...
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Unable to connect Android ADB over TCP/IP

I tried to connect to my phone through WiFi using Android ADB, but I can't connect it. I tried this steps: adb kill-server adb tcpip 5555 adb connect 192.168.1.16:5555 And got this message: ...
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What's wrong with this outbound iptables firewall?

I have a mail server which I'd like to secure by only allowing OUTBOUND connections on the various ports it uses. The inbound rules are working fine - they are handled by the VM host. I've not been ...
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Are errors and drops a normal thing?

My Router ( D-Link DSL 6850U ) has a status window for the LAN which shows the following: This is in contrast to the WAN statistics which show zero drops and errors. I wanted to know: 1) Does having ...
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Why does an unblocked TCP/IP port appear to be listening from one server but not from another?

I have Oracle VirtualBox on my Windows 10 machine (we'll call "hoster"). I have two linux VMs which are getting the same IP address (despite my efforts to give them different IP addresses). I tried ...
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Exploring TCP/IP Communications

According to the Lab, "The ping fails because the IP address assigned to the switch is not on the same subnet as the IP address assigned to the workstation. Even though they are on the same network ...
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Windows 7 NTLM not authenticating properly with Ubuntu 18.04

I've spent most of my day today trying to figure this out... Not exactly what I had in mind for today... but I couldn't help myself... So, here's the problem: My Windows 7 machine won't authenticate (...
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What if 2 session layers generate the same source port?

Is it possible for an application's session layer function to produce a source port which is already being used by another application for a current TCP connection? How are these kept unique? The only ...
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Why "Connection-specific DNS Suffix" is only (default) available for wired connection, not for wireless

I understand what and how to set "Connection-specific DNS suffix", and I mostly understand the purpose. My question is just about why only certain network connection/adapter has it by default (even ...
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Export Chrome Net-Internals Events

Are there any options for exporting data captured within Chrome's net-internals tool (chrome://net-internals/)? The only data that I care about are get requests for JavaScript files from a specific ...
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Wifi-Lan Port blocking

I'm writing a paired (windows) server and (android) client application suite that uses TCP connections over wifi on a funny port number. The Server advertises its availability using Bonjour/Zeroconf. ...
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OpenWRT noack and mcs rate

Are different MCS rates supported when you are running in noack mode? Context: I am using ath9k modems+Compex WPQ864 (linux-ipq864) boards. I have configured one of the boards as Access point and ...
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