All Questions
Tagged with tcp networking
477
questions
-1
votes
0
answers
16
views
My download speed is decreased on the browsers after these changes
I watched a network optimization video for Windows OS's on the internet and did some changings on my PC according to video. After what I did, I realized when downloading something via Brave it took ...
0
votes
1
answer
37
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 | ...
- 2,283
0
votes
1
answer
52
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
115
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
184
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 ...
- 3,263
2
votes
1
answer
768
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: ...
- 3,263
0
votes
0
answers
262
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
74
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
48
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
531
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
143
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
65
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
79
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
62
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
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
3
answers
442
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
113
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
1
vote
0
answers
211
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 ...
- 449
0
votes
3
answers
808
views
What happens between a TCP handshake and HTTP CONNECT?
When you have a system making HTTPS requests through a web proxy, my understanding is that there is the TCP handshake between the client and the proxy, then the client sends a HTTP CONNECT to ...
- 11
1
vote
1
answer
589
views
Retransmission of TCP packets
I have device A (10.10.25.1), which is connected to device B(10.10.25.52) via unmanaged switch. Device A is a computer. Device B is measurement instrument. Device A is continuously(every 1sec) sending ...
- 4,683
0
votes
0
answers
187
views
Windows can't connect more than 64k concurrency outgoing connection
I'm trying to make 100k concurrency outgoing connection from one pc to my local server.
My program can use specific ip on each connection.
Goal : 1 pc have around 100k concurrency outgoing connection.
...
0
votes
0
answers
2k
views
How to enable Windows 10 TCP keepalive?
As per this answer TCP keepalive can be enabled by three registry values. However, setting KeepAliveInterval=KeepAliveInterval=30000 miliseconds and TCPMaxDataRetransmissions=5 definitely does not ...
1
vote
1
answer
2k
views
Print Related Communication - RPC over TCP vs RPC over Named Pipes
In Windows 11, version 22H2. Microsoft made some changes to enhance security, one of those is the change in the communication of print related operations. Making RPC over TCP the default for client – ...
- 25
0
votes
0
answers
56
views
Miktrotik: disconnect TCP connection
I am working on a mobile device project. I have the mobile device connected on a local USB Wifi hotspot on an Ubuntu PC and I can WireShark the TLS connections which the mobile device creates towards ...
- 101
0
votes
0
answers
74
views
TCP Receiver's Window stop increasing
I'm debugging a high-bandwidth TCP connection whose throughput is significantly lower than the capability of the device and the network. The network between these 2 hosts is expected to be high ...
- 101
0
votes
0
answers
37
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 ...
1
vote
1
answer
3k
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. ...
- 121
5
votes
1
answer
812
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 ...
- 303
0
votes
0
answers
43
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