In case of IPv6 and NON Windows make sure to not listen on dualstack,

for that we need to create a socket2 socket and set_only_v6 to true.
We need to privude set_nonblocking for tokio to work and we need to set reuseaddr for it to work on linux systems

Cargo.lock

@@ -2893,9 +2893,9 @@ dependencies = [
 
 [[package]]
 name = "libc"
-version = "0.2.107"
+version = "0.2.116"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fbe5e23404da5b4f555ef85ebed98fb4083e55a00c317800bc2a50ede9f3d219"
+checksum = "565dbd88872dbe4cc8a46e527f26483c1d1f7afa6b884a3bd6cd893d4f98da74"
 
 [[package]]
 name = "libgit2-sys"
@@ -5383,9 +5383,9 @@ dependencies = [
 
 [[package]]
 name = "socket2"
-version = "0.4.2"
+version = "0.4.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5dc90fe6c7be1a323296982db1836d1ea9e47b6839496dde9a541bc496df3516"
+checksum = "66d72b759436ae32898a2af0a14218dbf55efde3feeb170eb623637db85ee1e0"
 dependencies = [
  "libc",
  "winapi 0.3.9",
@@ -6374,6 +6374,7 @@ dependencies = [
  "rustls 0.20.1",
  "serde",
  "shellexpand",
+ "socket2",
  "tokio",
  "tokio-stream",
  "tracing",

network/Cargo.toml

@@ -20,6 +20,8 @@ network-protocol = { package = "veloren-network-protocol", path = "protocol" }
 #serialisation
 bincode = "1.3.2"
 serde = { version = "1.0" }
+#ipv4/ipv6 behavior
+socket2 = "0.4.4"
 #sending
 crossbeam-channel = "0.5"
 tokio = { version = "1.14", default-features = false, features = ["io-util", "macros", "rt", "net", "time"] }

network/src/channel.rs

@@ -94,7 +94,20 @@ impl Protocols {
         s2s_stop_listening_r: oneshot::Receiver<()>,
         c2s_protocol_s: mpsc::UnboundedSender<(Self, Cid)>,
     ) -> std::io::Result<()> {
-        let listener = net::TcpListener::bind(addr).await?;
+        use socket2::{Domain, Socket, Type};
+        use tokio::net::TcpSocket;
+        let domain = Domain::for_address(addr);
+        let socket2_socket = Socket::new(domain, Type::STREAM, None)?;
+        if domain == Domain::IPV6 {
+            socket2_socket.set_only_v6(true)?
+        }
+        socket2_socket.set_nonblocking(true)?; //needed by tokio
+        let socket = TcpSocket::from_std_stream(socket2_socket.into());
+        // See https://docs.rs/tokio/latest/tokio/net/struct.TcpSocket.html
+        #[cfg(not(windows))]
+        socket.set_reuseaddr(true)?;
+        socket.bind(addr)?;
+        let listener = socket.listen(1024)?;
         trace!(?addr, "Tcp Listener bound");
         let mut end_receiver = s2s_stop_listening_r.fuse();
         tokio::spawn(async move {