All Questions
157
questions
0
votes
2
answers
1k
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,...
- 219
0
votes
1
answer
74
views
New LAN from Linux PC
I've got one Linux PC connected to the Internet but I want to connect more devices to the PC using TCP/IP but I don't want the router to act as a DHCP Server for them. I mean, I don't want the router ...
2
votes
1
answer
669
views
Why does my virtual machine (Debian on Proxmox) not respond to a TCP SYN of another VM even though it arrives?
I got a very strange problem and I am out of ideas to solve it. I hope anyone over here has a helpful idea.
Some info about the virtual machines:
VM0: Debian 10 - 192.168.10.102 [+ 2 more interfaces]
...
- 41
0
votes
1
answer
565
views
How can I assign an ephemeral port range to a specific linux service and not the entire IP stack
For example: If I want sshd to listen on 22 but use ephemeral ports of tcp 50-60 for communication.
0
votes
1
answer
1k
views
Meaning of IPTABLE duplicate values
I'm new to IPTABLES and when I execute the following command
/sbin/iptables --list -n | grep 16381
I could see multiple entries as shown below :
ACCEPT tcp -- a.b.c.d 0.0.0.0/0 ...
0
votes
0
answers
423
views
Can TCP implementation send several packets without waiting an ACK for the first one?
I basically know who TCP works from sockets point of view, but I can't figure out some thing.
Suppose I have now 1000 bytes to send, it comes for TCP-stack internal buffer and gets sent. These bytes ...
- 195
0
votes
1
answer
541
views
How can I identity which process is sending data to a certain host on Linux?
As per title, I want to figure out the process responsible for certain traffic. I can see the traffic in wireshark, but I don't know which process it is.
Is there any straightforward way to do it? I'm ...
2
votes
1
answer
6k
views
Prometheus Blackbox Exporter TCP probe returns value of 0, even when port is open (Iperf3 server)
I have a strange problem that I've been digging into the last couple of days.
The setup
I have an Iperf3 server running in Docker on this internal address and port: 10.10.2.2:5201
I also have ...
- 172
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 ...
- 63
0
votes
0
answers
94
views
Low-traffic network retransmissions and fails
I have an local network with generally very low traffic. On the network I have oscilloscope with LAN access, which I want to interrogate. When downloading samples (which come in blocks of a few ...
- 737
0
votes
1
answer
569
views
TCP Packet drops on application server
I have a monitoring application (Zabbix proxy) installed on RHEL 7.8 and since we have a very large environment, we have 2500+ agents connecting to this one server. We're seeing frequent errors while ...
- 101
0
votes
0
answers
229
views
How to allow only 100 half open SYN connections
I'm running Ubuntu and want to allow only 100 waiting SYN connections at a given time,
and drop the rest.
How can I configure iptables to implement this rule?
Or sysctl config to allow only 100, and ...
- 103
0
votes
1
answer
4k
views
Increase buffer size for a specific socket on Linux
I am using CentOS7 and I have to increase the send buffer size (SO_SNDBUF) on a socket listening on a specific port. The application that has the port opened does not natively support this.
Few things ...
2
votes
1
answer
1k
views
What would prevent a TCP server port (once closed), from being re-opened right away?
I have a server program that uses TCP.
Sometimes, I need to restart the program for updates, or any other reasons, but when I do, the program closes the server port, and then once it restarts, it ...
- 95
1
vote
0
answers
45
views
understand ss -to4 output for a jdbc connection
My application connects to a database over JDBC, and performs a lot of sequential inserts. There is only 1 JDBC connection opened by the application. As the performance is not as expected, I started ...
- 11