UDP message it's ok only with 127.0.0.1 local syslog server

[marcomoret]

Hi, I have a simple problem but is not possibile for me solve it
I start a little test to send a syslog message via UDP on 127.0.0.1:514 local syslog server and the test is ok. If I change 127.0.0.1 IP with real local server IP (10.250.60.50) the syslog message doesn't arrive on local syslog server

The C# test code is simple

private static async Task Main(string[] args)
{
try
{
string system = ConfigurationManager.AppSettings["system"];
int port = Convert.ToInt32(ConfigurationManager.AppSettings["port"]);
var log = new LoggerConfiguration()
.WriteTo.UdpSyslog(host: system, port: port, appName: "my-app", format: SyslogFormat.RFC5424, facility: Facility.Local2, outputTemplate: "{Message}")
.CreateLogger();

    Console.Write("SEND: This is test message - information");

    //SelfLog.Enable(Console.Error);
    await WriteLogs(log);
}
catch (Exception ex)
{
    Console.Write(ex.ToString());
}

}

private static async Task WriteLogs(ILogger log)
{
try
{
log.Information("This is test message - information");
log.Error("This is test message - error");
//log.Verbose("This is test message - verbose");
log.Warning("This is test message - warning");
log.Fatal("This is test message - emergency");

    await Task.Delay(1000);
}
catch (Exception ex)
{
    Console.Write(ex.ToString());
}

}

[cocowalla]

Did you check the firewall on the target machine has UDP/514 open for incoming connections?

[marcomoret]

yes, the firewall is stopped

[cocowalla]

Oh, I just realised you still want to hit the local server, just by IP instead of loopback.

You should check which NICs your syslog server is bound to - it might only be bound to the loop back adapter.

Also, is your C# app running in a container, or directly on the host?

[marcomoret]

host

[marcomoret]

sorry, the syslog server was configured to receive only from 127.0.0.1
thanks for all

[cocowalla]

No worries, it's an easy thing to miss, and this issue is bound to help others in the future 👍

[marcomoret]

my error on server syslog configuration