# UDP in/out broadcast issue

**URL:** <https://discourse.nodered.org/t/udp-in-out-broadcast-issue/18044>\
**Category:** General\
**Created:** [16 November 2019 17:43 UTC](https://discourse.nodered.org/t/udp-in-out-broadcast-issue/18044 "2019-11-16T17:43:53Z")\
**Posts on this page:** 8\
**Page:** 1

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**Author:** ![binks](https://avatars.discourse-cdn.com/v4/letter/b/f1d935/32.png) [@binks](https://discourse.nodered.org/u/binks)\
**Post date:** [16 November 2019 17:43 UTC](https://discourse.nodered.org/t/udp-in-out-broadcast-issue/18044/1 "2019-11-16T17:43:53Z")

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Hello,

I've found an issue while using UDP in/out with broadcasting.  
The scenario:

- **udp in** listening on port 57066
- **udp out** sending a broadcast packet and binding to local port 57066

(the goal is to discover another device IP address, and this device will reply when receiving a specific packet on a specific port).

When the **udp out** tries to send the message, it throws an EACCES error. This is because the SO\_BROADCAST flag is not set.  
Looking at the code, I see that **udp out** will reuse the socket of **udp in** if it already exists. But this socket will not have the broadcast flag.

If I change the code in the UDPout function by updating the code below, it works:

```auto
 node.tout = setTimeout(function() {
            if (udpInputPortsInUse[p]) {
                sock = udpInputPortsInUse[p];
                
                // start of modification:
                if (node.multicast == "broad") {
                      sock.setBroadcast(true);
                      sock.setMulticastLoopback(false);
                 }
                 // end of modification
                node.log(RED._("udp.status.re-use",{outport:node.outport,host:node.addr,port:node.port}));
                if (node.iface) { node.status({text:n.iface+" : "+node.iface}); }
            }

```

What do you guys think? Is it bug that could be corrected, or am I missing something?

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<div class="post-metadata">

**Author:** ![zwily](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/zwily/32/19807_2.png) [@zwily](https://discourse.nodered.org/u/zwily)\
**Post date:** [11 April 2020 21:11 UTC](https://discourse.nodered.org/t/udp-in-out-broadcast-issue/18044/2 "2020-04-11T21:11:04Z")

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I'm seeing the same behavior. Have you submitted a pull request?

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**Author:** ![dceejay](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/dceejay/32/38_2.png) [@dceejay](https://discourse.nodered.org/u/dceejay)\
**Post date:** [11 April 2020 21:30 UTC](https://discourse.nodered.org/t/udp-in-out-broadcast-issue/18044/3 "2020-04-11T21:30:31Z")

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not seen one - but happy to patch it anyway.  
can see that it would help

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**Author:** ![Larspalmqvistdk](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/larspalmqvistdk/32/39282_2.png) [@Larspalmqvistdk](https://discourse.nodered.org/u/Larspalmqvistdk)\
**Post date:** [27 April 2021 04:53 UTC](https://discourse.nodered.org/t/udp-in-out-broadcast-issue/18044/4 "2021-04-27T04:53:13Z")

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I have the same issue now one yar later, what do i do to get it fixed and what is the new release number, or how do i patch.

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**Author:** ![dceejay](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/dceejay/32/38_2.png) [@dceejay](https://discourse.nodered.org/u/dceejay)\
**Post date:** [27 April 2021 07:47 UTC](https://discourse.nodered.org/t/udp-in-out-broadcast-issue/18044/5 "2021-04-27T07:47:14Z")

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It was fixed at that time so has been in every release since then.

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**Author:** ![Larspalmqvistdk](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/larspalmqvistdk/32/39282_2.png) [@Larspalmqvistdk](https://discourse.nodered.org/u/Larspalmqvistdk)\
**Post date:** [27 April 2021 11:34 UTC](https://discourse.nodered.org/t/udp-in-out-broadcast-issue/18044/6 "2021-04-27T11:34:17Z")

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hmhm cant get it to work. i can listen for udp messages thats working , but cannot send, it is sending but dont think it gets oustide the container network. if i run it in host mode i cant get the ui, like the port is not mapped in host mode..

se boot up log looks fine  
27 Apr 11:29:55 - [info] Node-RED version: v1.3.2

27 Apr 11:29:55 - [info] Node.js version: v12.22.1

27 Apr 11:29:55 - [info] Linux 5.10.25-linuxkit x64 LE

27 Apr 11:29:55 - [info] Loading palette nodes

27 Apr 11:29:57 - [info] Dashboard version 2.28.2 started at /ui

27 Apr 11:29:57 - [info] Settings file : /data/settings.js

27 Apr 11:29:57 - [info] Context store : 'default' [module=memory]

27 Apr 11:29:57 - [info] User directory : /data

27 Apr 11:29:57 - [info] Projects directory: /data/projects

27 Apr 11:29:57 - [info] Server now running at [http://127.0.0.1:1880/](http://127.0.0.1:1880/)

27 Apr 11:29:57 - [info] Active project : node-red-docker

27 Apr 11:29:57 - [info] Flows file : /data/projects/node-red-docker/docker-custom/flows.json

27 Apr 11:29:57 - [info] Starting flows

MongoDB URL: mongodb://172.17.0.1:27017/Neets

27 Apr 11:29:57 - [info] Started flows

27 Apr 11:29:57 - [info] [udp in:NeetsDiscovery] udp listener at 0.0.0.0:8000

27 Apr 11:29:57 - [info] [udp in:Key changes] udp listener at 0.0.0.0:8001

27 Apr 11:29:57 - [info] [udp out:broadcast] udp broadcast ready: 2800 -\> localhost:8000

27 Apr 11:29:57 - [info] [udp out:Send from port 3000] udp ready: 3000 -\> :

27 Apr 11:29:57 - [info] [udp out:Send from port 3001] udp ready: 3001 -\> 🙂

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<div class="post-metadata">

**Author:** ![dceejay](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/dceejay/32/38_2.png) [@dceejay](https://discourse.nodered.org/u/dceejay)\
**Post date:** [27 April 2021 14:04 UTC](https://discourse.nodered.org/t/udp-in-out-broadcast-issue/18044/7 "2021-04-27T14:04:08Z")

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and you have exposed that udp port via docker ?

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<div class="post-metadata">

**Author:** ![Larspalmqvistdk](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/larspalmqvistdk/32/39282_2.png) [@Larspalmqvistdk](https://discourse.nodered.org/u/Larspalmqvistdk)\
**Post date:** [6 June 2021 14:23 UTC](https://discourse.nodered.org/t/udp-in-out-broadcast-issue/18044/8 "2021-06-06T14:23:16Z")

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Yep  
I Think i found out why, it's because i am on a mac where there is a layer in between.  
so it is not broadcasting om my house network only listening.

can this be true.

Lars