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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9 views

Can you recommend Ethernet/TCP/IP primer-plus reading material? [closed]

I'm sometimes stymied by lack of knowing exactly how some Ethernet/TCP/IP network elements work. I'm beyond the absolute basics, which are widely explained, but Q&A going beyond that often reduces ...
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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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Which protocol and port is used when I copy a file from one Windows computer to another Windows computer?

Which protocol and port is used when I copy a file from one Windows computer to another Windows computer? I find conflicting answers here and here. I want to know in both the scenarios where the ...
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TCP ping output explanation?

I ran a TCP ping from my Windows PC to google.com and following is the output : I was reading this thread to understand how TCP ping works and it mentions that a "half open scanning" is performed ...
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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 can I configure ddwrt to display hostnames instead of mac address in ddwrt screens?

I am trying to 'label' expected clients with names that will be displayed in wwdrt instead of mac addresses. i have several smart devices. maybe this is similar to reverse dns but done locally ...
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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 ongoing RDP connection a threat?

There is much information about how dangerous it is to have RDP open to WAN. But let us ignore all that risks with open port etc. for a moment. Let's consider the case when we have an ongoing RDP ...
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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 are the Length and the Pointer fields in the Record Route option filled?

I have problem understanding two things from RFC791: First, could the base-10 value of the length be greater than 40? (header without options is 20 bytes and HLEN is 15 at max)? What does "length-3" ...
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234 views

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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Make Windows TCP Connection Instantly Return From WSAECONNREFUSED like Linux

I have an application that talks to a server via TCP. The server used to run linux however we have ported it to windows. When I start my application it attempts to connect to a number of TCP ports on ...
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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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TCP/IP Metric priority gets reset on every reboot

I've adjusted the metric on an interface used for VPN to be of lower priority (10) than my LAN (1). This works right away and it works properly. Until a reboot. Every reboot resets the metric to 1, ...
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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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1answer
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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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1answer
39 views

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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832 views

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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1answer
945 views

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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216 views

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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672 views

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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Practical (vs theoretical) max limit of TCP packet size

I'm a web developer who is pretty new to the industry. I was presented with a coding challenge for a job interview where I need to design a messaging system and architect a system for how it deals ...
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689 views

How can Ping not use a transport protocol?

I just learned that Ping uses ICMP directly, i.e. it bypasses the transport layer. How is that possible? Shouldn't an application (L5) use UDP or TCP in the transport layer (L4)? The way I know it is ...
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What is the reassembly path of a HTTP response?

I am trying to understand how operating systems generally implement reassembly of network requests. From my best understanding the following is true: A HTTP request is made at the application layer ...
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1answer
3k views

How to make `nc` listen on a port without setting `SO_REUSEPORT`

I want to have a nc command listen on a TCP port so I did: nc -lv 8888 Then in another console I checked if another program trying to listen on the same port would get an Address already in use type ...
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Double NAT MTU setting for the inner network

I have a home network with two routers, one behind another. The outer router's WAN port is a VDSL2 PPPoE connection with a live IP address and the MTU size of 1492. The inner router's WAN port is ...
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613 views

tcp session - http request [ x out of y] in wireshark capture

As below, i am seeing this [HTTP request 1/2] and [HTTP request 2/2] in 2 separate payload, are they separate GET request in a single tcp session or are they the same GET request ??? ==== Added full ...
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Windows 10 LAN or WiFi networking gets 169.xxx address on DHCP or static

Surface Pro 4. Windows 10 1709 16299.251 Looking at the above device for a friend. When connecting to network on WiFi it asks for key instantly, and when type in, attempts to connect and then comes ...
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RST hijacking good ACK number

I'm trying to perform a RST hijacking sur on my Virtual Machine. I have 3 Vm's: -attack : 172.10.10.11 -victim : 172.10.10.21 -pirate : 172.10.10.31 First, I connect from attack with telnet to the ...
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Why default route is required to access inbound ports

I have this network configuration: - Local router 10.0.0.1, public IP 1.2.3.4 forwarding port 1002 to 10.0.0.2 forwarding port 1003 to 10.0.0.3 - Local host 10.0.0.2, server on port 1002, no ...

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