Questions tagged [udp]

UDP stands for User Datagram Protocol. With UDP applications can send messages (datagrams) to other hosts on a network without requiring prior communications to set up special transmission channels or data paths.

Filter by
Sorted by
Tagged with
0 votes
2 answers
52 views

OpenVpn doesn't connect via TCP

I created a OpenVpn server with TCP but client can't connect and receive this error Server poll timeout, trying next remote entry... But UDP works perfectly. This is config of server: local a.b.c.d ...
0 votes
0 answers
22 views

Where could my packets be being blocked?

I am working on a video streaming project, I have issues when sending above a certain amount of traffic (something like 20 Mbs) I no longer receive any packets. Some quick facts: Windows task manager ...
  • 11
0 votes
0 answers
13 views

Multiple NIC on the same computer: the traffic on a NIC causes delay on the other NIC

I have a 1GB pci-express NIC peer-to-peer connected to an ethernet video camera. When there is ethernet traffic on the other integrated NIC (for example during a 4k streaming video from youtube), ...
  • 1
0 votes
1 answer
31 views

Strange limitation on single TCP/UDP connection with bandwidth limitation

I have a weird behaviour with connections from my house in Israel to my VPS or dedicated server in the EU. A single connection TCP/UDP is somehow limited to around 400kbps for some reason. When using ...
  • 11
1 vote
2 answers
71 views

Rsyslog: relay messages from UDP input only

Considering a docker container which receives logs on UDP and forwards to a central logging server using TLS, I was wondering if I could be satisfied with one queue or if I needed several. Indeed, ...
0 votes
0 answers
152 views

FFmpeg doesn't write to HLS output (udp multicast input)

This is the output from ffprobe. Input #0, mpegts, from 'udp://239.0.0.80:2345?localaddr=192.168.2.127': Duration: N/A, start: 39580.799967, bitrate: N/A Program 60 Metadata: ...
0 votes
0 answers
32 views

tunneling vpn through proxy

I am connected to internet through a college network through a proxy I want to connect to Network through openvpn but my college proxy is dropping it as it is a udp how do I connect to the network ...
0 votes
0 answers
57 views

Why am I seeing persistent write IO when sending large UDP traffic on a virtual switch?

I have a virtual switch in Hyper-V: That switch has a network configuration giving it an IP network. The intent is to use it as a "host-only" network between the host and a guest I have ...
  • 281
0 votes
0 answers
104 views

How to allow my C Server access from outside localhost

I'm trying to run an UDP Client-Server message exchange program for a university course, when I try it in a local network even with different PCs works really fine. But the moment I try to run it on ...
1 vote
1 answer
66 views

Change UDP traffic on the fly. Searching for Network device

I have one specific hardware which generates UDP traffic but due to one single issue inside the UDP data part, another device can't correctly work and skip UDP packets. Please, can you suggest to me ...
  • 111
1 vote
1 answer
221 views

Why does my internet connection only work properly with a UDP-based VPN?

My house is connected to the main router in another building via a single LAN cable that is run partially underground, partially outside (along the wall of the house). There is one switch on the route,...
  • 11
0 votes
0 answers
895 views

VPN Server behind CGNAT

I have 2 homes: home1 is using an ISP with CGNAT, home2 has a public ip address. I'd like to be able to connect from anywhere to a Wireguard VPN server from home1 (SH1) and use that connection to ...
  • 101
0 votes
0 answers
64 views

Achieving high DNS QPS throughput

I'm trying to find the maximum QPS (Query Per Second) of the DNS Resolver VM. We have our infrastructure hosted on Azure, having a VM (bind based) acting as a resolver querying Azure native DNS (168....
  • 121
0 votes
0 answers
157 views

UDP packets dropped with `ctstate=INVALID`, but meanwhile its connection `[ASSURED]` in conntrack list

I have my router connecting to a remote VPS as so-called 'VPN' that is based on UDP protocol, then the VPS traffic slows down in few seconds after a new reboot. I can see a huge amount of incoming ...
  • 1
0 votes
1 answer
340 views

iptables SNAT for UDP rule is only applied to some traffic

I want to use Source NAT to change the local IP address of UDP traffic. However, only locally-generated traffic has the NAT rule applied, replies to traffic generated from remote sources do not have ...
  • 13
1 vote
1 answer
705 views

wireshark bad udp length > ip payload length

I have a custom made (not by me) imaging device here. It connects to a computer via ethernet cable. The companying application software guides the user in the process of acquiring an image. So far so ...
  • 544
0 votes
0 answers
35 views

forwarding subnet broadcasts in a small test environment

In my test lab I have a small, inexpensive, unnamed router to create two subnets, 12.1.1.0 and 172.17.2.0. The router is configured in Router mode (not Bridge), and I have a bridge defined that joins ...
  • 101
0 votes
2 answers
771 views

Multiple default gateways on Windows

I have a custom made imaging instrument to which I connect using ethernet cable and to make it work I have to set static IP and gateway on my laptop's network interface connected to the device. ...
  • 544
0 votes
0 answers
43 views

Curl Commands parallel on two seperate shells

I am testing the download speed of a website with curl and want to run one with TCP and the other with UDP on two different VM´s. But I want to measure both of them at the same time so that I know how ...
user avatar
0 votes
2 answers
711 views

The maximum length of a Datagram Packet is 65,536 or 65,535?

I found both answers on the internet. I think it should be 2 bytes = 2^16 = 65,536, but on Wikipedia it is written that it is 65,535 : The field size sets a theoretical limit of 65,535 bytes (8-byte ...
  • 633
0 votes
0 answers
60 views

fwknop does not work from Windows

I am trying to gain access to a server which runs fwknop from a Windows 10 laptop which runs WSL. If I copy the .fwknoprc file to a remote Ubuntu server let's call it 1.2.3.4, I see that SSH is ...
  • 3,513
0 votes
1 answer
107 views

No connectivity between hosts on UDP port

Host with IP address 192.168.212.49 is not able to reach host with IP address 10.50.140.179 via UDP 4501 port. ICMP (ping) communication is possible. There are two routers between these hosts. Note: ...
1 vote
0 answers
255 views

Change UDP IP address

I'm trying to hide my WebRTC IP to a proxy server(x.x.x.x:yy) that I use to hide my identity, when I go to Ipleak I can see that my real IP is revealed. when I use common VPN services out there, not ...
  • 11
1 vote
1 answer
799 views

Does port forwarding 9 for Wake On Lan expose my network to attackers?

I'm trying to set up Wake on WAN so that I can turn on my computer when I'm not home. By port forwarding UDP 9 everything works flawlessly, but I'm concerned of the security risks.
0 votes
0 answers
263 views

Why is dig failing but tcpdump showing a response?

I have a situation where my dig command is failing with a timeout error when querying DNS over UDP, but when I check the packets with tcpdump it shows a valid response. I have a working server to ...
0 votes
0 answers
61 views

Returning tcp/udp packets to sender

I'm using a Linux machine with WiFi hotspot to test the WiFi stack of an embedded device. For context, the embedded device is designed to send and receive encrypted packets to/from a remote server. To ...
1 vote
1 answer
1k views

How to check if my network is blocking UDP traffic?

I have noticed that some applications on my phone are unable to connect when my phone is connected to my home WiFi, while they do work over 4G, even though my WiFi connection is fast and stable. I ...
  • 121
0 votes
0 answers
282 views

How do I intercept all udp packets and redirect them to a proxy?

System: win10 64bit . I want to positively intercept all UDP packets and then tunnel them through a proxy 127.0.0.1:29918, so they will all have to go through this proxy in order to reach the outside ...
0 votes
0 answers
63 views

A datagram of 2020 bytes is being sent and the MTU is 1020 bytes. The headers have 20 bytes. How many fragments are created, and what is the offset?

A datagram with a total of 2020 bytes is being sent. The MTU is 1020 bytes. Assume the headers have 20 bytes. a) How many fragments are created and what are their sizes? b) What is the offset and the ...
0 votes
1 answer
152 views

Why should one expect a ~30% drop in speed when using OpenVPN UDP with NordVPN? [closed]

https://support.nordvpn.com/Connectivity/1047408902/Speed-and-bandwidth.htm (mirror) mentions: If you are connected to the closest available server through OpenVPN UDP, you can expect around a 30% ...
0 votes
1 answer
3k views

How to run wireguard over tcp with udptunnel?

I'd like to run wireguard over tcp. I wanted to use udptunnel for sending udp packets over tcp. However, when I run wireguard and then try to run udptunnel, the udptunnel fails with the following ...
  • 101
0 votes
0 answers
1k views

How to port forward UDP though SSH

I have a setup where I'm forwarding port 5000 to a remote server with ssh -NR 5000:localhost:5000 root@server This only forwards TCP packets through the SSH tunnel, Due to new software which is picky ...
0 votes
1 answer
37 views

Sending a UDP message stream - listener hanging after first receive

I'm attempting to use nc to send a stream of messages from one server to another using UDP. On the sending side, Centos 7.5, I'm doing the following: for s in $( seq 1 20 ) do echo "$(date +'%...
2 votes
1 answer
1k views

Can't receive UDP data unless Wireshark is running

We have a computer system (Win10) that receives a variety of UDP data from a remote host at various rates (2-50Hz). The remote system is provided by our customer. While we're waiting for the customer ...
  • 269
2 votes
1 answer
128 views

how to protect udp packets from packets loss?

when i tried to ping with mtr using udp pinging i gets packets loss from outside wan the result of (mtr 8.8.8.8 -s 576 -n -u): 5. 149.6.154.169 ...
  • 23
0 votes
1 answer
48 views

Impact of Enabling UDP Checksum (IPv4) on the System

AFAIK, UDP checksum is an optional feature on IPv4. I want to enable it on a gateway (IPv4), but I want to know if it has any negative impact on the system, e.g., increasing CPU utilization or ...
0 votes
0 answers
310 views

What does it mean for a SOCKS5 proxy to have UDP enabled?

v2ray has options for enabling UDP for a socks5 server. What does this mean? How is it usable? How can I test the server to see if it is working correctly?
  • 860
0 votes
1 answer
987 views

Configure openvpn for ExpressVPN TCP ports

I want to use the openvpn client on my Ubuntu 20.10 to connect to ExpressVPN's VPN. Unfortunately I have to use the TCP ports, as the UDP ports are blocked. ExpressVPN's website only allows to ...
0 votes
0 answers
88 views

how to get udp unicast to two hosts?

The two hosts need to have to same ip. My solution at the moment is a port mirror, but the problem is as mentioned the duplicate of the ip address, I think. I couldn't find a way to disable the IP-...
1 vote
0 answers
199 views

Why is my wifi router delaying broadcast UDP packets?

I have a Python program running on my raspberry pi that opens a socket to receive broadcast packets (actually ArtNet lighting protocol). The pi uses its built-in wifi to connect to a D-link wireless ...
  • 11
1 vote
1 answer
1k views

What is this UDP traffic to 230.0.0.1? And how can I block it?

My VM is of IP 192.168.3.20 in the network of 192.168.3.0/24. While running iptraf command on my machine, I am getting the response as shown in the attached image. I can't understand what kind of ...
0 votes
0 answers
83 views

UDP packets sent to wrong IP?

I have an IPTV box connected to my only router that assigned it a local IP 192.168.1.165. I tapped the LAN cable right next to tv box and recorded traffic in Wireshark. There I saw a remote IP from my ...
  • 183
0 votes
0 answers
18 views

How to set different TTLHOP for TCP ports

We want to set sensitive TCP/UDP Ports at low TTL/HOP Leaving other ttl/hop at 128 default data center = 3 Priv net = 8 Internet = 128 default Ssh 22 = 8 (internal hop max) Rdp 3389 = 8 Http 80 = 128 (...
0 votes
0 answers
54 views

Constant receiving UDP packets from other local PC and firewall failed to block that specific IP address [duplicate]

Is it normal for a PC to keep sending out UDP packets to other local devices using random source ports? In my case, I'm using Wireshark to monitor my own Windows PC network and I found there is one IP ...
0 votes
0 answers
117 views

How to route all Ethernet traffic to a Serial port on a Linux system?

How can I route all Ethernet traffic on a Linux system to a Serial port and the opposite? I want to convert from the first architecture to the second one, as shown in the picture: picture I monitored ...
0 votes
0 answers
32 views

Routing from via remote bridge

Below is a diagram of my server and laptop, both inside the same LAN. On the left, I have a server with a bridge ip (.128). The server also allocate another ip (.118) from the router but only ...
  • 1
0 votes
2 answers
628 views

Protocol on Wireshark says LLC

enter image description here A theoretical question may be. I have created UDP traffic across my network involving client and Server. When i ping the server and monitor the data using wireshark, it ...
0 votes
0 answers
235 views

Chrome reports UDP port blocked but netcat can connect

I am using Chrome browser 84.0.4147.89 (64-bit) and when I run the Chrome Connectivity Diagnostics I get the following error log for UDP port 19302-19309. SUMMARY Test Name: Hangouts Connectivity ...
  • 173
0 votes
0 answers
603 views

WireGuard blocked - apparently a wider UDP issue

WireGuard is refusing to connect, I've tried running it on 2 different VPS providers (with my PC as the client) and it just doesn't work. There are some commonalities which I noticed: On both ...
0 votes
0 answers
3k views

buffer deadlock prevented error from RTSP streaming over UDP

I have an issue to view RTSP streaming over UDP in the open VPN connection. Our project is to integrate 360 degree IP camera in unity system. And we want to get the UDP streaming rather than TCP to ...

1
2 3 4 5
7