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1 vote
1 answer
54 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
7k views

Connection timed out when connecting to a remote tcp port

I have deployed my application on Linux CentOS. The app connects to a remote TCP port but it throws a connect timed out exception. I tried to connect it via telnet but the port doesn't respond. I am ...
0 votes
0 answers
355 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 ...
1 vote
2 answers
9k views

TCP to virtual serial port with socat

I have a program (program 1) that has a TCP server listening on port 1234. I have confirmed that the server accepts connections and sends data with a utility str2str. Program 2, on the same machine, ...
2 votes
1 answer
769 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: ...
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, ...
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 ...
4 votes
3 answers
23k views

ping works but iperf3 doesn't show any traffic for TCP

machine A has IP (eth0: 192.168.1.1, eth1: 10.10.xxx.yy) machine B has IP (eth0: 192.168.1.2) A and B are connected through RJ5 on eth0, both sides. ping works fine on both side, but when running ...
0 votes
1 answer
873 views

How do I run a permanent tunnel in localxpose?

I am able to create a localxpose tunnel in ubuntu with this command: :loclx tunnel tcp but when I close my local connection to my server, the tunnel closes with it. Is there a way to keep a tunnel ...
0 votes
1 answer
780 views

is it possible to OpenVPN connection UDP through SSH tunnel?

Hi i search a lot on the Internet, especially in this site and read more post and articles about using OpenVPN connection through SSH tunnel but all tutorials about using TCP protocol to do that. in ...
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 ...
4 votes
2 answers
245 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 ...
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 ...
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 ...
2 votes
1 answer
3k 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 ...

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