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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.

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How to improve reliability of RADIUS (FreeRADIUS) when used for TOTP (LinOTP) authentication with possible packet loss?

We're using AWS SSO with TOTP over RADIUS. Our RADIUS server is a FreeRADIUS with linotp-auth-freeradius-perl. The problem is the connection between AWS SSO and FreeRADIUS is not completely reliable - ...
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UDP broadcast with nc not received (Ubuntu)

I'm trying to understand UDP broadcasting, and running into some trouble. 1 - Running a server like this nc.traditional -l -u 10.0.0.253 -p 65001 2 - Sending stuff from the client like this - on the ...
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How to limit UDP port range with K8s + Calico + Wireguard

We have several Kubernetes clusters at Hetzner using Calico (vxlan) with security enabled (Wireguard tunnels). The recent Hetzner outages knocked everything offline: Due to always different ...
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Dynamic tunneling of mosh via a DMZ/corporate firewall

I've read this: mosh tunnel via proxy, but want to beyond the solutions offered there. Scenario public internet private intranet [Client] <----------------> [Proxy] <----...
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Could someone please explain the difference between these expressions

drop proto tcp and not (dst port 80) pass proto tcp and dst port 80 Is there a difference between them?
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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....
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UDP packet won't send if it is too small

I am in an incredibly odd situation. Basically if I try to send UDP packets smaller than 1445 in size they never end up reaching their destination. I have a pretty ordinary router and a pretty ...
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Forward UDP ipv6 port in a VPS to UDP ipv4 port in another VPS

I have VPS let's say VPS X that doesn't have IPv4 but only has IPv6. and I have VPS let's say VPS Y that doesn't have IPv6 but only has IPv4. Since IPv4 is still common used today, and some device ...
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Duplicated UDP packets sent

We have a few applications that we develop in my company that talk to some hardware via UDP. Recently, we started having issues using these applications on some of our machines (hardware basically ...
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UDP Packets Lost (Ubuntu 18.04 into Windows 10)

I am trying to send UDP packets from Linux machine (Ubuntu 18.04 ) to a windows 10 machine. But the packets are not received at the Windows machine. I have already send UDP packets from Windows 10 to ...
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KeepAlived UDP Load Balancer with DTLS

I have a cluster of servers that rely on UDP for client communications. Among the few LBs that support UDP there is KeepAlived which however operates at layer 4: I have a minimum of experience with LB ...
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Rolling updates of backend with udp server sockets

I have a backend system used for IOT devices which use UDP protocol for communications. And there are certain TCP (HTTP2) based APIs for mobile apps from the same backend. I am trying to build a ...
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rsyslog - Lower throughput when using omfwd with TCP vs UDP

TLDR; I'm getting significantly lower throughput when forwarding syslog messages with rsyslog on a Redhat server with 32 cores and 128Gi RAM to a remote server using TCP instead of UDP syslog in the ...
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how can i fix this udp error when using nginx

0 I have a problem for which I have not found a solution anywhere. The problem is that we have deployed proxy servers in front of our game services and here we use haproxy for tcp traffic and nginx ...
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netstat reports UDP ports with no owning process

When I run netstat -avp udp I get a slowly growing number of ports. It grows about 100 an hour but the rate varies considerably. When I close the process, the ports do not disappear from the list. ...
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How can I forward TPROXY and its UDP port to a sub-net?

I can forward a transparent proxy to a sub-net with: iptables -t nat -A PREROUTING -i eth2 -p tcp --syn -j DNAT --to-destination 127.0.0.1:10000 But how can I do the same with TPROXY? I want to ...
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UDP port forwarding between virtual machines and docker composed network

currently I'm deploying a virtualized system and having a problem with forwarding of an udp port. I tried many tutorials, but something must be wrong and I don't know why the connection is refused all ...
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Forward broadcast packets to dynamic / wildcard

I have set up a dynamic ppp service on a linux machine where clients will connect and get a private IP. The rules I have set up in iptables are currently: sysctl -w net.ipv4.ip_forward=1 sysctl -w ...
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UDP servers High Availability allow random source IP response

My system is composed by a NGINX configured as load balancer waiting for UDP datagrams. The client open an UDP socket, assigning a random source port, and sends a request, waiting for a response. Say ...
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iptables NAT REDIRECT

I have a server that is receiving syslog traffic. Many of my devices can only send to the default udp/514 port. My syslog server can't run on ports <1024 and is running on 5000. I have a nat ...
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3 votes
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nginx config for reverse proxying UDP traffic (minecraft app) - 90 message too long

Trying to proxy udp traffic. nginx doesn't throw any error about the configuration. The client connects until half-way (it says it could reach the end server) but the connection then gets stuck and ...
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hping3 in scan mode crafting UDP packets with bad length:

I'm attempting to scan UDP ports 1-1000 using HPing3 and so to this end enter the following: sudo hping3 -2 192.168.1.2 --scan 1-1000 -V I know that UDP port 1 is not closed and should be responding ...
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nmap not detecting clearly open udp port

I've opened port 4000 on my local machine as follows: nc -lvup 4000 and then attempted to connected to the same port as follows: nc -vu 127.0.0.1 4000 and was able to successfully connect and send ...
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Stopping UDP Attack

I am now getting support emails from OVH that there is unusual activity on my server. This is a simple server that I have RDP connections for students to access QuickBooks, Excel, and Word, and there ...
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Huge CPU usage when enable rsyslog TLS

We currently using rsyslog for gathering logs from ~1M IoT devices, we used to use plain-text UDP syslog and our server handling those just fine with minimal system load, but now because we need to ...
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How do online games send UDP packets across the internet?

How do online multiplayer games which use UDP get the packets delivered between networks over the internet? From what I understand, clients would have to enable port forwarding on their routers in ...
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UDP to Serial port

I look for some solution for connect serial/UART port by UDP connection to another PC. Now I use socat and have connection , but with lost packages, and slow transfer. Can I use netcat for this, maybe ...
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Udp punchhole between two instances behind two different cloud NAT on GCP

Hi I'm trying to achieve UDP punchhole concept between two compute instances (on different networks with no public IP) behind two different cloud NATs for their respective networks. It seems that in ...
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UDP packets received internally but not externally - Ubuntu 18.04

thanks in advance for taking a look at this... I'm confident that the solution is simple - it's just I don't know what it is. Running nc -l -u 9090 AND nc -uv 82.165.109.4 9090 command on the same ...
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How to identify source, destination ip using STUN and DTLS protocols?

enter image description here Given image i'm not able to identify which is source and destination ip address ( client or server). From STUN protocol 1st packet it's user request so i thought 131.202....
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Docker macvlan drops UDP (DNS) traffic, TCP works

I'm trying to use macvlan to create a container that is a first-class citizen on my lan. I'm using a static IP (although I understand that using some 'tricks' it's possible to use DHCP as well). I ...
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iptables redirect udp traffic from one interface to another, or from one host to another on the same interface

iptables -t nat -A PREROUTING -p udp -m udp --dport 1197 -j DNAT --to-destination 1.2.3.4:8081 On eth0 I am receiving udp packes destined for port 1197. I want to emit those packets on another ...
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Routing inbound and outbound udp traffic to the same port in kubernetes

This is a follow-up to a prior question I asked, but with a different ask/approach. In case it matters, I'm on GKE, but I'm hoping there's a cloud-agnostic answer. I'm trying to run the container ...
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Kubernetes managing many distinct UDP servers on GKE

I'm trying to set up a system that can automatically spin up and down video game servers as docker images. In this case, factoriotools/factorio-docker. Each game is a different, distinct single-pod ...
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WebRTC Turn (coturn) server UDP vs TCP vs DTLS ( UDP )

We've some situations were some clients with default ISP router firewall and router IDS system can't connect to our PBX ( Grandstream UCM6510 via WEBRTC ) , testing configurations we've found that if ...
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when router sends ICMP protocol error message how does it set it's own TTL?

when using (traceroute -q 1 serverAddress), we know that it starts with TTL(Time to Live) = 1. when it goes through router, the router decrements TTL by 1. If TTL becomes 0 at that router, it sends ...
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Debian udp port fowrding to another server does not work?

I have PC A (192.168.255.126, eth1) and it will receive some UDP packets, port: 51000. Now I wish the PC A will automatically forward the UDP packets to PC B (192.168.255.127) I have found many ...
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NGINX UDP Proxy Pass to HTTP

I built a NGINX reverse proxy where I listen for UDP traffic on port 53 and pass it on to an HTTP endpoint with modified headers. Once the headers are modified, I send the packet to the target. http....
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How 2 dynamic (external) IP devices can talk to each other via 1 static (external) IP [closed]

I have 3 devices: Device 1 (Dynamic IP): A raspberry Pi sending UDP packets to Device 2 via 4G modem via Internet Device 2 (Static IP): My Ubuntu/Windows PC with static IP, successfully receives ...
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Forwarding UDP traffic from one host to another

I have two hosts, each with 2 network interfaces: host1: eth0:172.16.125.5 eth1:172.165.8.55 host2: eth0:172.16.125.6 eth1:172.165.8.56 I want to forward all UDP traffic to host1:eth1 port 1234 to ...
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WCF Discovery on Windows Server 2019 getting ICMP Typ 3 Code 3

The problem: I've installed Windows Server 2019 and I am trying to discover my WCF services running on a Windows Server 2012R2. But that's not working and in Wireshark I see a ICMP Destination ...
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Are there STUN implementations that can sometimes handle symmetric NATs?

I've been working on connecting two devices that are each behind a symmetric NAT and managed to make it work quite consistently. However, it takes quite some time for the connection to happen (...
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huge difference in RX bytes vs TX bytes (ifconfig) on Syslog-NG server

we have a syslog-ng server acting as an intermediary logger. the server receives data from all devices on the network (from many different sources, on both UDP & TCP ports), filters them a bit, ...
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Fix UDP issues on subnet

I currently have a network with the following topography: topography Networking is fine and all works well, except for one thing: UDP seems to be unstable/not working on the subnets 192.168.3 and 192....
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Increased CPU interrupts, degraded performance on upgrade to Symfony flex

We're upgrading our Symfony 3.4 app (LAMP w/ opcache/php-fpm) to flex (as per https://symfony.com/doc/current/setup/flex.html). In load testing, we're seeing increased CPU usage, particularly system ...
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Forward incoming UDP Packets on Windows Server to client on different interface

I have the following setup with 2 networks and 3 clients: Network A: 192.168.0.0/16 Network B: 172.16.0.0/12 Client 1 is connected to Network A (192.168.0.1) Client 2 (Windows Server) is connected ...
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Video streaming via UDP on gigabit ethernet = packet lost

We are observing a strange behavior on a video streaming application over UDP on the same LAN. The sender send an H264 video via UDP through ethernet configured as 1000BaseT-FD, the receiver receive ...
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ncat script to test source IP addresses with UDP load balancer

I have two Ubuntu Virtual Machines behind an Azure Load Balancer. I'm observing some inconsistencies with the source IP addresses set in outgoing UDP packets from the VM's. I'm trying to come up with ...
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upstream timed out (110: Connection timed out) while proxying connection - Nginx/Raspberry Pi/Ubuntu 20.04

I cannot find any help with UDP, so I have come here to ask. I have a DNS cluster set up on Raspberry Pis running Ubuntu 20.04 and Nginx. The proxy is used for UDP on port 53. I am needing to put this ...
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Enable GRO for UDP port explicitly

I am implementing a simple socket application in python and I need it to receive UDP packets with GRO enabled. I have checked that only the Python service is running and that GRO is enabled via ...
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