Questions tagged [udp]
User Datagram Protocol (UDP) is defined to make available a datagram mode of packet-switched computer communication in the environment of an interconnected set of computer networks. This protocol assumes that the Internet Protocol (IP) is used as the underlying protocol.
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I can't block a port with ufw
This morning I received a report from Netscan:
Netscan detected from host 8X.19X.1X.1XX
time protocol src_ip src_port dest_ip dest_port
Fri Sep 15 05:21:59 2023 UDP 8X.19X.1X.1XX 5065 => 9.87.179....
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Is NFS proto=udp supported in RHEL 8 nfs-utils-2.3?
I can get vers=3 to happen, and I can get mountproto=udp to happen, but I cannot get a proto=udp to happen on the nfs client. I can only get proto=tcp on the nfs client.
Is proto=udp supported in nfs-...
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difference NFS proto and mountproto
in RHEL 8.8 when I am trying to test NFS tcp versus udp and versions 3 versus 4.0, 4.1 and 4.2, I observe on my nfs client a mountproto= in addition to proto= when typing mount. What is the ...
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How to send UDP broadcast datagrams to port below 1025?
Scenario
I'm trying to send a UDP datagram message with socat to a broadcast address.
On the receiving end this is how I'm running socat (with root privileges):
socat UDP-LISTEN:1011 -
I'm trying to ...
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openvpn client cannot connect via UDP, but TCP works fine
problem:
I've setup a new ubuntu 20 vm on esxi and installed openvpn. It can connect to multiple vpn servers, like protonvpn, but only through tcp, not udp.
troubleshooting:
Used netcat to verify ...
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Traceroute from VM guest does not go past Host PC to internet
I have created an Ubuntu virtual machine on my PC, and I was trying out the traceroute command, as I need it for a college project. However, when I ran "traceroute www.google.com", what I ...
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understand different UDP packet loss results: iperf3 vs nuttcp
I try to measure UDP [%packet loss] between two machines.
I'm getting different results while using two different tools:
iperf3:
machine 1: iperf3 -s
machine 2: iperf3 -c <machine_1_ip> -u -...
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Can i trust echo result of nc command for UDP?
Context :
I want to test UDP port with nc command
What happens :
nc command return nothing on output and 0 when i put echo $?
Which command :
nc -vzu <ip> <port>
echo $?
What is the ...
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Ncat very slow over UDP. Possible causes?
I've got three servers, "a", "b" and "c", all in same /24 subnet mask.
On all of the servers, to any of the two other servers, nc to TCP port 9999 consistently takes 0.01 ...
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Check whether SOCKS5 proxy server support UDP
Suppose I have UDP server that listen incoming message on 192.168.43.1:1234 and SOCKS5 proxy server that listen on 192.168.43.2:9999.
How do I check whether SOCKS5 proxy server support UDP when ...
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command that shows all online connections?
I used TCPView to see all TCP and UDP endpoints in Windows. Is there any linux command/gui that has similar functionality?
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facing isue in UDP multicasting after changing ip of the device
we have a requirement for UDP multicasting in our project using Linux 4.1 kernel with static ip address.
basic UDP multicasting using sendto function to send data is working fine with device static ip ...
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socat tunnel traffic drops after some time
I have two Linux machines, I want to create a tunnel between them using socat, this is my workaround:
Machine1:
socat -d -d UDP-LISTEN:4711,reuseaddr TUN:10.50.50.1/24,iff-up,iff-broadcast,iff-...
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Is there a good way to balance UDP packets over multiple ports?
I'm not really sure where to turn, so I'm hoping that someone can help me out.
My ISP is very aggressive with various types of throttling.
It throttles UDP traffic by port. With incoming UDP traffic ...
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Is it possible to make the softirq run on the core the user wants?
My system:
NIC: ConnectX5 MCX516A-CCAT (100GbE NIC)
OS: Ubuntu 22.04 LTS
CPU: Intel Xeon Silver 4314 (Dual CPU, 16Core + 16Core)
I'm doing UDP communication using a 100GbE NIC.
However, if the task ...
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Why do udp requests fail temporarily
I've a UDP web server, which bound to the port 10000. I just deployed it on the server 172.20.0.10. Then I tried to scan the port nc -v -z -w2 -u 172.20.0.10 10000, it seems that everyting is OK. The ...
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Is it possible to detect if a process is trying to create a socket connection but the remote server refused
Let's say that I have a process on my local Ubuntu. I want to know if it would use some socket connection(TCP or UDP) to connect some remote server, which has been turned off, meaning that any ...
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Check what service is running on a specific tcp/udp port
I'm looking for a command-line utility that allows me to check what service (eg: http/ftp/ssh) is running on a specific port of a remote machine.
An example of how I imagine a program like this would ...
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socat streaming UDP is slower than TCP
I'm currently using subprocess.run(["socat", f"udp-listen:{_to},fork,reuseaddr,bind=127.0.0.1", f"""exec:'sudo ip netns exec {netns} socat STDIO "UDP-connect:...
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socat does not honor sourceport option
I am trying to send a udp packet from a specific port:
$ echo hello | socat - UDP-DATAGRAM:192.168.1.255:11111,broadcast,sourceport=22222
But a random port is used instead:
# tcpdump -vvvv -ttttt -...
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Using UDP multicast in Linux, recvfrom() cannot get data
I have a task to get data from a sensor device. Through the Wireshark, I can capture information as below:
wich send information from 10.13.1.113 to 224.0.2.2 (Multicast Address). Src Port 42402, Dst ...
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Does the correctness of MAC address matter in UDP?
Here is the thing, I used tcpdump and created a UDP-only pcap file from production environment.
Then with the tool tcprewrite, I updated the UDP packets dst IP and MAC address as vm2, src IP as vm1 ...
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Blocking UDP port 140 from receiving packets from source port 8989 (active way to send signal to sender that is unreachable)
So my problem is that I want to block UPD port 140 from receiving packets from port 8989, but I want to block it actively, not just silently ignore it, but to send an active signal to the sender of ...
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TCPDUMP IP UNKNOWN
I am seeing this in the tcpdump output
21:32:51.580969 IP UNKNOWN.9998 > 255.255.255.255.9998: UDP, length 12
What does 'IP UNKNOWN' mean? Is something hiding the ip address?
Thanks
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Is there a tool to count the latency of UDP datagrams in Linux?
Now I want to test the network performance between two Linux systems.
The test scenario is as follows: one terminal sends UDP datagrams to the other terminal continuously at fixed intervals (the ...
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what does `IgnoredMulti` statistic for Udp in debian linux mean?
I have a Ubuntu machine that is receiving UDP packets by joining a multicast group, occasionally we are getting UDP packet drops.
when I am trying to monitor using netstat -s I get the following ...
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How can I send a UDP packet from my Linux ASUS router?
I have changed the firmware on my router, unanme -a yields:
Linux RT-AC86U-8458 4.1.27 #2 SMP PREEMPT Fri Aug 6 18:32:35 EDT 2021 aarch64 ASUSWRT-Merlin
I have logged in to ssh to this router, and I ...
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NFS client won't list files when using UDP
I have an NFS server (server1) that works fine with TCP, but when a client mounts it with UDP, while the mount point works, it can only list folder with no files in it. If there's a file in that ...
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How to get open connections statistics without ss or netstat
The question may sound silly but I'm trying to make a tool that uses ss data. Sadly I'm having some troubles regarding output format parsing (too much randomness depending on version and system).
So, ...
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How to drop all unnecessary UDP traffic on INPUT chain?
About 2 weeks ago, I started running a Tor relay, which itself operates solely on TCP.
So, I would like to drop all UDP packets, which are unneeded.
But I don't know, what is actually needed (if ...
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tcpdump, determine transport protocol
Is there a easy way to determine the transport protocol of a packet by looking at the output of a TCP dump trace?
I'd just like to be able to tell if a packet is UDP or TCP. I've tried using the -x ...
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Low-level tcp/udp proxy
Is it possible to set up a server which acts as a proxy that is able to delegate all incoming traffic (regardless of protocol) to the original destination?
What I am trying to do is to allow only a ...
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Iptables Accept All From Specific Ip And Port
I want to accept all traffic that is coming from an IP address and its specific port to any of my ports.
Here is the configuration:
Details:
I am using Jitsi in a server, and I want to reach Jitsi ...
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How to setup veth with 9000 MTU to simulate sending and receiving large UDP multicast packets on the same host?
The sender needs to transmit large data packets to the receiver (which is on the same host with 1500 MTU) and I think this can be simulated using veth with 9000 MTU, from my reading on it. But I'm not ...
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Only Flatpak apps can open all websites after connecting to VPN
I'm using PureVPN app (openvpn/udp). Installed via rpm file. After connecting, If I ping youtbue.com it shows:
--- youtube.com ping statistics ---
7 packets transmitted, 0 received, 100% packet loss, ...
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reordered and duplicated packets when using UDP over loopback interface
We are seeing UDP packets being reordered and duplicated when being sent over lo. We can see this because we're sending MPEG transport streams, which have their own sequence number in their headers, ...
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linux bridge interrupts udp packet flow
I am having a UDP issue with the following bridging setup (Linux 5.11.6):
(let ns${i} denote namespaces and left${i}/right${i} be veth pairs)
ns1{right1(x.x.x.1)---}---ns2{---left1::bridge(x.x.x.2)::...
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Script that performs an action based on the contents of a UDP packet?
I'm trying to write a script that listens for broadcasted UDP packets on port 2088, read the data, and then POST to an URL. Specifically, I'm trying to make a LIFX light turn red when I'm on the ...
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Netcat listener: Line break between syslog messages
I am playing with netcat command. On this linux system, I have set up a netcat listener on UDP 514, so that I get to see syslog messages from remote systems.
$ sudo nc -v -ulp 514
listening on [::]:...
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Any way to block UDP for a specific applcation
Is there any way on Linux to block UDP traffic for a specific process. I tried using AppArmor deny of certain traffic, but it only supports total denial of all network access, not a specific protocol. ...
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How to convert stream data which come over udp to video device?
I'm trying to share my computer's camera with the remote computer. In order to do this, I wanted to share my own computer's camera with the udp port(stream), take the stream on the remote computer and ...
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incoming UDP multicast stream stops after fixed time on macOS
My ISP provides IPTV feature, stream example: udp://@239.255.2.97:5500. I'd like to watch IPTV on macOS, so I used VLC.
Initially, IPTV didn't work at all. At first I thought that it's locked to ISP's ...
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Linux: UDP "multiplexer" inside kernel
I have an application with very high performance requirements and the following job: There is incoming UDP traffic on port 1234. The packets have as fast as possible to be sent to hosts H1, H2, ... Hn ...
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Sending multiple packets of hex data with UDP
I'm trying to reverse engineer a wifi webcam that connects to an Android app. I sniffed the traffic and found that the transaction is initiated when the app sends a series of 8 UDP packets, at which ...
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state of tcp/udp source ports when waiting for answer from target
i have a quick question about tcp port states: suppose i am establishing a tcp connection to a server: source address/port should be 44.44.44.44:33456 destination address/port is 55:55:55.55:443. in ...
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Socat: send a UDP broadcast from stdin, but handling responses with SYSTEM
I'm trying to implement a simple proprietary discovery protocol using socat. The discovery is done by sending a UDP broadcast to a well-defined port with a small payload, then listening to "...
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UDP Packet drops
I understand that the receive flow for a UDP packet is
Check udp header for errors
Match destination to socket
Send an error message back if no such socket
Put packet into appropriate socket receive ...
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Why is it that TCP packets can be modified to block invalid packets, but not UDP packets
On a random day I was googling iptables rules to harden my desktop, and came across this post[1]. At some point the guide mentions blocking invalid TCP packets using tcp-modules with these rules;
...
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Bridge / Tunnel using netcat and named pipes
I have two devices (A and B) that should communicate with each other - indirectly via a server (S):
/---\ /---\ /---\
| A | <===> | S | <===> | B |
\---/ \---/ \---/...
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Why did iperf3 show thunderbolt speed 3 Gbit in one direction, and just 500 Mbit in the other direction?
I connected two MBPs via thunderbolt, via thunderbolt bridge which should provide 10Gbit/s bidirectional connection on one of its channels.
I have them connected over a thunderbolt 2 male male cable ...
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