Questions tagged [tcp]
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.
908
questions
0
votes
0
answers
594
views
wazuh agents cannot connect using cloudflare tunnel
I installed wazuh in docker on my synology which exposes the following ports:
0.0.0.0:1514-1515->1514-1515/tcp, :::1514-1515->1514-1515/tcp
On the same machine (also in docker) i am running a ...
- 147
0
votes
0
answers
29
views
Seeing several thousand retransmits every 10 sec. via iperf3 on TCP traffic through a propritary network bridge device
What is the most likely cause of TCP packet fastACKretransmits when testing with iperf3 on a small 5-7 node Linus AutoIP network running on a TI AM5728 board? Where and what setting should we check ...
2
votes
1
answer
2k
views
UDP client to listen to a multicast group/port without setting its own IP?
I have a small microcontroller device that I program via USB using Python. The device has an Ethernet connection, which can be configured either with DHCP or by manually setting the IP/Subnet via USB. ...
- 481k
4
votes
2
answers
241
views
linux service TCP Gateway with service starting
Is there a service (linux) that starts the service on an incoming TCP request (if it does not already exist) and then forwards it to the application? For example, for a docker container that would ...
- 316
5
votes
1
answer
792
views
Iptables Fail to block inbound from specific ip
Hi I Have a online server which i use like gateway and iptables is acting weird
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -i ...
- 5,936
0
votes
0
answers
94
views
TCP splicer/splitter (proxy)
There's a big problem with satellite ISP's, that is shaping any TCP-connection to 4 Mbps.
Since alomost any software uses single TCP-connection, resultinhg speed is limited.
I've encountered ...
- 1
0
votes
1
answer
224
views
Http proxy server for unit test to connect to sftp through java
I am successfully able to connect to sftp over http proxy using paramiko library in python using
ncat —proxy command
Now I want to test it using java junit test. I am able to successfully create ...
- 1
1
vote
1
answer
1k
views
Changing the TCP initial congestion window value in Windows 10
I would like to do some testing with the TCP Initial congestion window on Windows 10 Pro, but it seems the settings are disabled in the Pro version:
Set-NetTCPSetting -SettingName InternetCustom -...
- 26
0
votes
0
answers
36
views
Teardrop detected from TCP ACK from myself
I'm experimenting with linux (Debian 5.10) networking to allow me to connect two networks (eg. 192.168.0.0/24 with 172.17.0.0/16) together.
Setup
In my case it is a small server with one NIC, hosting ...
- 126
1
vote
2
answers
1k
views
How do I get traceroute to work like tcptraceroute?
On Mac OS 11 the man page for traceroute says you can set it to TCP mode with -P TCP. When I attempt to do this I get no responses:
[me@laptop ~]$ sudo traceroute -f 6 -m 10 -e -P TCP -p 443 www....
- 2,057
3
votes
3
answers
7k
views
Send TCP with incorrect checksums
I'm having trouble sending large files to an OpenStack machine.
Our Internet connection is over LTE so bad packets are to be expected. However, even sending data over TCP results in corrupted data ...
- 21
0
votes
0
answers
85
views
ppp(d) configuration options: Does "noccp" also disable vj compression?
I'm having trouble understanding the docs for pppd. The Oracle man page states that disabling CCP (using noccp) disables deflate and bsdcomp - both of which are data section compression.
However, it ...
- 6,805
1
vote
3
answers
4k
views
Understanding port forwarding and NAT
I've got some confusion about port forwarding vs NAT. I know the problems NAT causes for P2P, and that there exist some solutions to it (STUN,TURN,etc) which require a relay server to setup direct ...
CommunityBot
- 1
0
votes
2
answers
259
views
Why do we need L7 reverse proxy for increasing the limit of max TCP connection to the backend?
I stumbled upon a YT video- 5 mins which explains that there's technically no limit to the number of connections that can be opened between the clients and servers even if there's a reverse proxy ...
- 481k
1
vote
0
answers
28
views
Windows8 drops network connection shortly after boot (but works if I wait)
I have a test lab which runs tests against Windows8 machine, more specifically a Pytest project which generates TCP traffic from my Ubuntu machine to Windows8 machine, and from the Windows8 machine ...
- 111
2
votes
1
answer
2k
views
How to force `telnet` (in TCP mode) to send bytes immediately?
In Linux, when I run telnet <address> <port> and then type things, it buffers data and only sends collected line when I hit Enter. Furthermore, it buffers up to 4096 characters and ...
- 454k
0
votes
0
answers
28
views
File service latency is high, How to troubleshoot?
This service is a file upload service and the request packet capture in the live network is as follows:
The data uploaded by the client is halfway through, and then it will not be sent
The server ...
- 6,805
0
votes
1
answer
278
views
How to send back TCP packets using iptables
I am trying to demonstrate TCP communication with a Ubuntu 18.04 box (which mocks a QNX setup) that does not have a listener installed. Consider that due to some license issues it might not be ...
- 7,756
1
vote
1
answer
2k
views
Trying to stream a video loop using FFMPEG. However, I keep getting the error "Cannot Write the Headers Server returned 400 Bad Request"
I am using mediamtx for starting RTSP server. The command that I am using for ffmpeg is as follows:
ffmpeg -re -stream_loop -1 -i ./clouds.mp4 -f rtsp -rtsp_transport tcp rtsp://localhost:8554
The ...
- 111
0
votes
0
answers
478
views
Termux ssh connection over usb-c result in connection closed by remote host
I got an Oneplus 8 with Kali NetHunter.
I want to ssh to Termux and I can, but only if the device connect to my LAN at least once.
If I restart the phone and I jump the connection with WiFi/internet ...
- 1
9
votes
1
answer
2k
views
What prevents unsolicited internet packets from using up my monthly data limit?
My home router can use port-forwarding to act as a server, so I assume all internet packets
sent with my public IP address as a destination are hitting it (and just not getting any
response from my ...
- 454k
0
votes
1
answer
52
views
Download so many tiny files without archiving? [closed]
I want to implement a file server for a mobile app. This app requires so many tiny files to be downloaded from the server before it begins it's work And with updates from version to version some files ...
- 454k
4
votes
1
answer
13k
views
Is it possible to check whether there is a firewall blocking a port?
Can netstat be used to check if my path to a particular port on a remote computer is blocked by a firewall or simply there is nothing listening on it?
If not, is there a suitable utility for this?
CommunityBot
- 1
1
vote
2
answers
553
views
TCP window probe
I was referred to this site when originally asking in the Networking SE.
I have a few questions about rwnd advertisements in TCP. I have read the RFC but was left with unanswered thoughts (or maybe I ...
- 461
5
votes
3
answers
15k
views
TCP vs UDP. Sending data on a closed port
I try to understand differences between TCP and UDP packet on the error-checking. I know that UDP packets are connectionless and doesn't care that the packet will arrive the destination safely. And ...
- 268
1
vote
1
answer
53
views
Is it normal to get no retransmissions using TCP on Nordic Boards?
For a Projekt I am connecting 2 Nordic Boards together over IEEE 802.15.4 and measure their bandwidth using TCP. The two nrf52840dk Boards are 1m apart (one acting as a border router for my PC).
...
- 11
2
votes
1
answer
2k
views
Why are DHCP messages broadcast?
I am learning DHCP in my networking class and as a part of my research, I was watching the following video:
https://www.youtube.com/watch?v=0UvLRVlPx6A
In the Wireshark capture in the above video (at ...
- 1,292
1
vote
3
answers
1k
views
How does a Router/Modem obtain the Port Number from an IP Datagram?
The IP datagram header is a layer below the TCP segment which contains information on the port.
Therefore before a firewall can inspect a port number, must the IP datagrams be rebuilt into the TCP ...
- 111
1
vote
1
answer
84
views
Low Windows bandwidth in google cloud platform
I have an on-premise site with mainly Windows resources and an up-to-date Forti firewall as the central communication device. This site is connected through a partner interconnect created according to ...
1
vote
1
answer
1k
views
What is stored in the "Winsock Catalog"?
Another user's question prompted me to write this one.
I have no purpose for the question other than curiosity.
Does anyone actually KNOW what is stored in what is called the Winsock Catalog? At the ...
- 157k
2
votes
1
answer
5k
views
Man in the middle using iptables
I wish to test a subsystems which communicates with another subsystems via tcp. I have used the following:
"iptables -A OUTPUT -p tcp --dport "+port_number" -j DROP"
to stop the traffic on a port so ...
CommunityBot
- 1
0
votes
2
answers
576
views
socat TCP server bidirectional using sleep, non-interactive client returns without response. Server reports: I/O error
I have the following TCP server:
socat TCP-LISTEN:10000,fork,reuseaddr SYSTEM:'read -r msg && sleep 3 && echo "OK"'
When I execute (interactive mode):
socat - TCP:localhost:...
- 161
0
votes
0
answers
2k
views
TCP Retransmission (TCP Port numbers reused) issues
I developed a web server and this is running on GKE.
Whenever I send any request to this server from my local pc, it occurs TCP retransmission.
Following is captured packets with Wireshark. The red ...
- 111
0
votes
0
answers
159
views
What cause client not to sent [ChangeCipherSpec] package
I face a problem. i have a device when doing TLS handshake, Client fail to send [ChangeCipherSpec], currently all https website is failed but http is working.
i check it from wireshark, it show as ...
- 5,832
1
vote
2
answers
1k
views
why TCP window scale values (scaling factor) are different in different hosts?
why TCP window scale values (scaling factor) are different in different hosts?
why not make this value the same on all hosts?
in theory, this value is between 0-14. what is the practical range for ...
- 198
0
votes
0
answers
339
views
Why does my LAN NIC get a lot of TCP retransmissions and timeouts?
yesterday I recognized that git cloneing repositories from my private GitLab instance wasn't working consistently. My internet connection is fine and I can also visit GitLab's web interface without ...
- 41
0
votes
2
answers
401
views
tls wrapper over plaintext tcp
is there any tool I can make tls forwarder over raw tcp?
I have a server which has no encryptions, purely plaintext tcp comunications.
I wanna connect to it over tls but cannot change the server code.
...
- 23
1
vote
1
answer
160
views
How can I get connection attempts behind a NAT router?
I've been playing with nftables recently and set up logging every incoming TCP SYN packet to my local machine. I noticed every minute I get a couple of random connection attempts on various ports (...
- 454k
2
votes
1
answer
527
views
Python TCP socket connection between Linux and Windows10 not working as expected
I am trying to establish a TCP connection and sending packets over a python socket server-client. I am using Windows 10 as my main system and VM Kali-Linux on the other side
I used Windows as a client ...
- 55.6k
13
votes
4
answers
39k
views
How to send binary data in netcat to an already established connection?
I can do the following to send binary data in netcat:
echo -e '\x80' | nc host port
But I don't want to do it like this, what I want is to connect to a server:
nc 192.168.1.115 12345
And then send ...
- 74.3k
11
votes
3
answers
27k
views
Examine open TCP connections on Mac
What is the Mac equivalent of TCPView or CurrPorts? I've never used Mac before, so I'm clueless.
- 21
0
votes
2
answers
529
views
How to run a program as administrator
Is this a joke?
Nothing as simple as running a program as administrator: click-right on the name of the program in Windows explorer, choose "Run as administrator" from the context menu and ...
- 2,251
12
votes
2
answers
2k
views
Is it possible to force TCP to find another path to the host?
I have two operating systems on my computer, in one TCP normally finds the path to the host, and in the other traceroute breaks off halfway. Is it possible that the route is somehow cached? If so, is ...
- 186
7
votes
1
answer
3k
views
ICMP packet with TCP?
For some time now I have found myself interested in packet analyzing and I try to figure out all kinds of stuff that I see in network captures. I hope you guys might want to help me find out this one.
...
- 454k
37
votes
5
answers
102k
views
How can I see 127.0.0.1 traffic on Windows 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 ...
- 101
1
vote
1
answer
201
views
Possible to use shell script that does loopback to localhost when receiving a packet?
I want to run a shell script, that sends a packet to localhost (loopback) when it receives a packet from anywhere.
I am using netcat.
nc -lp $port, and then echo test | nc localhost $port works.
But, ...
- 21
1
vote
0
answers
274
views
Port Forwarding not working on cellular data but working on wifi
I recently developed a web app using Express and Node.js and I am hosting it locally on my PC. I set up my router to port forward HTTP requests to the web app to my PC. It works fine whenever the ...
- 104k
0
votes
0
answers
953
views
ModuleNotFoundError: No module named 'pyModbusTCP'
I am trying to run a python file on bootup which will collect some data from another device.
I created a service in the /etc/systemd/system directory
[Unit]
Description = File which requests data from ...
- 33
0
votes
2
answers
790
views
How to measure the latency to a webserver?
I wish to measure the TCP network latency from my Linux server, to a websocket URL.
I am using netperf like this:
netperf -H ws.the_websocket_url.com -l 5 -t TCP_STREAM -v 2 -- -o min_latency,...
- 481k
2
votes
1
answer
7k
views
What does Firefox's PR_CONNECT_RESET_ERROR mean?
When I browse to https://unesco.org from Firefox, I get the error PR_CONNECT_RESET_ERROR. But https://www.unesco.org works.
I couldn't find Firefox's documentation on this error despite several Google ...
- 1,038