The udp-balancer() source allows you to use multiple CPU cores to process the incoming UDP messages at a very high message rate, depending on the available hardware resources, incoming message size, and your syslog-ng PE configuration. Note that this feature requires a Linux kernel that supports the SO_REUSEPORT kernel option, so it is supported only selected platforms.

The udp-balancer() source uses multiple CPU cores that listen on a single UDP port. This allows the source to scale to very high message rates. Using a single port is convenient, because you do not need to use load balancing on the client side. You can set the number of listeners using the listeners() option. For the best performance, the value of the listeners() option should be equal to the number of cores available on the host running syslog-ng PE.

When to use the udp-balancer() source

One Identity recommends using the udp-balancer() source if all of the following apply:

  • You are running syslog-ng PE in relay or server mode on a platform that supports the udp-balancer() source. For details, see Limitations.

  • You must receive UDP message at a high message rate, and for some reason you cannot use TCP connections instead.

  • It is not critical for you to store the incoming messages in the order they were sent.

Limitations

  • The udp-balancer() source is using eBPF, therefore it works only with kernels that support eBPF. From the platforms supported by syslog-ng PE, the following kernel versions have been tested:

    • Debian 10 (Debian Buster)

    • Oracle Linux 7.7, kernel version 4.14.35

    • Red Hat Enterprise Linux 7 is NOT supported, because its kernel version is too old.

    • Red Hat Enterprise Linux 8, kernel version 4.18.

    • SUSE Linux Enterprise Server 12.4, kernel version 4.12.14

    • SUSE Linux Enterprise Server 15, kernel version 5.3.18

    • Ubuntu 18.04 LTS (Bionic Beaver), kernel version 4.15

    • Ubuntu 16.04 LTS (Xenial Xerus), kernel version 4.15

  • Since the udp-balancer() source is multithreaded, there is no way to guarantee that the destination of the log path will receive the messages in the same order as the clients sent them. If you need to maintain the original order of the messages, make sure that the log messages contain a unique identifier (for example, a message ID or timestamp), and that your log processor (for example, a SIEM) can use this ID to reorder the messages.

Declaration
udp-balancer([options]);

By default, the udp-balancer() driver binds to 0.0.0.0, meaning that it listens on every available IPv4 interface on the UDP/514 port. To limit accepted connections to only one interface, use the localip() parameter. To listen on IPv6 addresses, use the ip-protocol(6) option.

Example: Using the udp-balancer() driver

Listening on 192.168.1.1 (the default port for UDP is 514):

source s_network {
    udp-balancer(
        ip("192.168.1.1")
    );
};

Listening on the IPv6 localhost, port 2222:

source s_network6 {
    udp-balancer(
        ip("::1")
        port(2222)
        ip-protocol(6)
    );
};

Listening for messages using the IETF-syslog message format. Note that for transferring IETF-syslog messages, generally you are recommended to use the syslog() driver on both the client and the server, as it uses both the IETF-syslog message format and the protocol. For details, see syslog: Collecting messages using the IETF syslog protocol (syslog() driver).

source s_network {
    udp-balancer(
        ip("127.0.0.1")
        flags(syslog-protocol)
    );
};

Using 8 listeners to receive logs on port 5514:

source s_net {
    udp-balancer(
        listeners(8)
        port(5514)
        log-fetch-limit(10000)
        log-iw-size(10000)
        );
};

For details on the options of the udp-balancer() source, see udp-balancer() source options.