Another thing to keep in mind, udp is unreliable so different outbound
interfaces will most likely take different paths and many under stress will
drop udp traffic - some always, especially on unknown ports - which is not
correct behavior but it happens over the internet. You shouldn’t see this on a
local network. Also, when you send out over a different interface than how it
arrived the destination may not be able to route due to nat translations -
which is why as you’ve found that you best bet is to send using the same
interface it arrived on - but strictly speaking this should not be required -
this is the underlying principle of internet routing.
> On Aug 26, 2019, at 7:38 PM, Robert Engels <reng...@ix.netcom.com> wrote:
>
> If the network is set up properly the kernel should chose the correct network
> interface based on the destination IP address.
>
> The only time this doesn’t apply is with multicast packets so as to not flood
> the network. In this case you set the interface you want to send on.
>
>> On Aug 26, 2019, at 3:47 PM, 'Tanner Ryan' via golang-nuts
>> <golang-nuts@googlegroups.com> wrote:
>>
>> Hi,
>>
>> I was hoping someone could help me with an issue. I have a simple UDP server
>> that listens on a specific port, responding with a message back.
>>
>> conn, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4(0, 0, 0, 0),
>> Port: *port})
>>
>> When reading messages, I use the source address for sending a response back.
>>
>> n, sourceAddr, err := conn.ReadFromUDP(buff)
>> conn.WriteToUDP(reply, sourceAddr)
>>
>> When my WAN interface has a single IPv4 address, the server can read and
>> respond properly. When there's an additional IPv4 address on the WAN,
>> requests to the second IP are successful received, but the response is not
>> received by the original sender.
>>
>> Is there another way to fix this other than explicitly calling ListenUDP on
>> the two addresses?
>>
>>
>> Best,
>> Tanner
>> --
>> You received this message because you are subscribed to the Google Groups
>> "golang-nuts" group.
>> To unsubscribe from this group and stop receiving emails from it, send an
>> email to golang-nuts+unsubscr...@googlegroups.com.
>> To view this discussion on the web visit
>> https://groups.google.com/d/msgid/golang-nuts/accf321d-75ad-4afb-9709-54ced8b37c5e%40googlegroups.com.
--
You received this message because you are subscribed to the Google Groups
"golang-nuts" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to golang-nuts+unsubscr...@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/golang-nuts/C721BC6E-5E6A-478E-8294-61940FE9E098%40ix.netcom.com.
