All Questions
Tagged with tcp networking
476
questions
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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
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1
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51
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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....
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106
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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
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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
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0
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229
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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
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73
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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
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1
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46
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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
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0
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499
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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
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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
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64
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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
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0
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77
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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
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60
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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
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0
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88
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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
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3
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396
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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 '/...
