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.
915
questions
-1
votes
0
answers
17
views
I need assistance with the default credentials of the YIIOT T-27 camera (Necesito ayuda con las credenciales predeterminadas de la cámara YIIOT T-27) [closed]
English Translation (via Apple Translate):
I have a YIOT IP camera model T-27 and I can't find the default credentials to access it. I have tried common combinations such as admin/admin, admin/12345, ...
1
vote
1
answer
37
views
Capture TCP stream with tcpdump/netcat
I have a hardware device that hosts two separate TCP modules. One is for receiving commands from other machines, while the other is a TCP stream server that sends data based on the commands received. (...
0
votes
1
answer
30
views
How to simulate Hercules on local IP address?
I would like to simulate a TCP server, using Hercules (by HW-Group).
When I configure the port (12714), netstat -aon | findstr "12714" shows me this result:
DOS Prompt>netstat -aon | ...
- 2,281
0
votes
1
answer
51
views
How do we reach an IP address?
How does the following work in TCP/IP protocol?
There are two subnets:
subnet A is 10.0.0.0/8
subnet B is 10.20.0.0/16
A host in Network A with an IP address of 10.20.3.4 wants to access a host 10....
0
votes
0
answers
306
views
Minecraft server using ngrok for port forwarding stopped working
So I built a PC using pieces I had laying around to make into a Minecraft server. I installed Ubuntu on it (I think it's the latest version because I installed it like a week ago. I didn't manage to ...
0
votes
0
answers
70
views
ARP request is successful, but TCP SYN is not visible in output of Wireshark
I was redirected from Network Engineering, hopefully below is in scope of on-topics.
I have a TCP server, its properties are the following:
It runs within a virtual machine (VMware).
The host OS is ...
0
votes
0
answers
106
views
Linux netfilter: How to capture, modify and retransmit packets that my host is sending to a specific destination?
I am trying to write a linux service that captures the packets that go from my personal server to a specific destination and performs necessary changes to them. More specifically, i want to find all ...
2
votes
1
answer
183
views
Are extra flags discarded in TCP exchanges?
A "normal" TCP handshake looks like this:
MachineA �� SYN → MachineB
Machine B → SYN,ACK → MachineA
MachineA → ACK → MachineB
This means that for each step, a flag (or set of flags) is ...
- 3,253
2
votes
1
answer
671
views
How to explain sequences of FIN,ACK instead of FIN - FIN,ACK?
Context: newly installed Debian 12, I get a bunch of strange logs related to ssh:
root@square:~# journalctl -u ssh -f
May 07 11:13:00 yop-square sshd[766]: error: kex_exchange_identification: ...
- 3,253
0
votes
0
answers
229
views
PowerShell: Diagnose timeout vs. connection refused on TCP port with Test-NetConnection
I frequently need to diagnose network connectivity issues and I'm currently using Test-NetConnection in PowerShell (Version 5.1). The output tells me if a port is reachable. In case it's not, I would ...
- 56
0
votes
0
answers
23
views
Delivery of packets to the correct web servers when they run in same machines
For example, I run two web servers in a single machine (only a single NIC available).
They use different ports (let us say: 1200 and 1201)
Now when a client (say from a mobile device or a browser from ...
- 111
3
votes
3
answers
1k
views
How does HTTP Keepalive handle multiple requests along with EOF from same origin?
says a client has multiple files to post to a server via HTTP Post method, there will be two api calls. since I don't want to create two TCP connections and I want to reuse TCP connection, so I use ...
- 135
0
votes
0
answers
73
views
Linux 6.5 netfilter NAT reuses TCP ports in TIME_WAIT status?
In my understanding, Linux (netfilter)'s NAT doesn't reuse TCP ports in TIME_WAIT status, but seemingly Linux >= 6.5 reuses TCP ports in TIME_WAIT, even if the destination is the same.
For example, ...
- 41
0
votes
1
answer
46
views
How TCP handle mutiple concurrent requests from same host
Say there is a web server that exposes port 80 with two endpoints, one for returning datasetA, the other for returning datasetB.
I have an application that does multithreading so I might send two ...
- 135
0
votes
0
answers
499
views
How can I fix this? “XRAY: transport/internet/websocket: failed to serve http for WebSocket > accept tcp [::]:8443: use of closed network connection.”
Recently I bought a Germany based VPS server to create my own VPN using v2ray because I live in Iran and the internet is heavily censored here.
I connected my domain to CloudFlare CDN to avoid my ...
- 1
1
vote
1
answer
137
views
Explicit Congestion Notification (ECN), Why isn't the notification done by the Router?
Quoting from Wikipedia:
"When both endpoints support ECN they mark their packets with ECT(0) or ECT(1). Routers treat the ECT(0) and ECT(1) codepoints as equivalent. If the packet traverses an ...
0
votes
1
answer
64
views
Connecting delay on local network (SYN RETRANSMISSION)
Somebody knows what could be the issue?
More often than not I can not connect instantly to my IP camera or local server and have a initial delay of around 10 seconds before it connects to the camera (...
user1888803
0
votes
0
answers
77
views
Ethernet connection loses upstream UDP and TCP packets but downstream UDP packets are fine
2 of my PCs are connected to my router like so:
Both PCs' ethernet cables -> Switch -> ethernet cable -> ethernet socket -> ethernet cable from socket -> switch -> ethernet cable to ...
- 398
0
votes
0
answers
118
views
Pgbouncer: Multiple Instances on same host receiving same TCP connection when using SO_REUSEPORT
I was able to setup two pgbouncer instances for database connection pooling, on a single VM (CentOS 7.0) listening to same port (6432) on two different TCP socket (I believe) using Linux Kernel ...
- 17
0
votes
0
answers
60
views
Linux Server - Bandwidth test doesn't change during TCP Tuning process
I'm new to network administration and have a question.
I am conducting research on whether it is possible to carry out TCP tuning using the genetic algorithm method. To do this, I wrote a Python ...
0
votes
1
answer
89
views
Proxy tunnel without ssh?
I've gone down a bit of a networking rabbit hole recently, and I've seen people make their own proxy with ssh. I was wondering if I could do the same with raw tcp?
0
votes
0
answers
88
views
VirtualBox internal network will allow ping and traceroute but not nc
Update: tcpdump shows only ARP traffic with nc generating ARP traffic who has 192.168.254 tell 192.168.1.64 but tracepath says tell Fedora who has 192.168.1.5. 192.168.1.5 is pingable but 264 is not. ...
0
votes
1
answer
77
views
Difference between 100Mbps 1000Mbps INITIALIZATION-state
What is the physical difference between 10Mpbs, 100Mbps and 1000Mbps (BASE-T) INITIALIZATION.
10Mbps and 100Mbps does not use all of the 8C8P(RJ45) pins. Does 1000Mbps utilize the full 8 pins for ...
- 1
0
votes
1
answer
43
views
What kind of data structure is used by TCP to keep track of received and missing bytes for purposes of forming correct SACK numbers?
Say I have a client that successfully receives packets from server in the following bytes ranges: 0-99, 100-199, 200-299. The next packet 300-399 gets lost but the final one 400-499 is successfully ...
- 237
0
votes
3
answers
396
views
Understanding how ports work and how are they different from processes?
I've been a part of a network operations team for quite some time now and was extracting a certificate using this command:
openssl s_client -connect <IP>:<PORT> </dev/null | sed -n -e '/...
0
votes
0
answers
68
views
Wireshark showing packet exchanges with unconnected IPs
Running Wireshark on a PC for network monitoring and I noticed something strange. Application data is being exchanged with websites that are not open in the browser, or on any other device on the ...
- 9
1
vote
0
answers
108
views
Gateway responding with ACK instead of server. Causes RST
I have a service running on my LAN which works very intermittently. It serves a webpage just fine right after I restart the server running macOS 14.1 (I noticed this happening on multiple versions of ...
- 11
0
votes
2
answers
95
views
Can two client browsers use the same port to talk to a web server? [duplicate]
When a socket is created between a client and host, it includes the IP address, protocol used and port number of both.
Suppose I have socket A (10.0.0.1, TCP, 50000) and (10.0.0.2, TCP, 50000) each ...
1
vote
0
answers
201
views
How to remove several Active Connections established by Firefox in the background to seemingly some local API server
When I checked active connection on my Windows with netstat -ab command, I found that Firefox has established several active connections to this seemingly local API. It had the name of a software ...
- 439
1
vote
1
answer
238
views
TCP Port 999 Garcon
I did an NMAP today on Desktops at different sites. Some of those Desktops show TCP port 999 being open with Garcon. I then ran wireshark (5-10 mins) and saw no traffic going to/from it. Does anyone ...
- 13