# The loggen manual page ## Name `loggen` — Generate syslog messages at a specified rate Note: If you don’t have AxoSyslog installed and want to run `loggen` from a container, you can use: Terminal window ``` docker run --rm -ti --entrypoint "" ghcr.io/axoflow/axosyslog /usr/bin/loggen [options] target [port] ``` ## Synopsis `loggen [options] target [port]` ## Description Note The `loggen` application is distributed with the AxoSyslog system logging application, and is usually part of the AxoSyslog package. The `loggen` application is a tool to test and stress-test your syslog server and the connection to the server. It can send syslog messages to the server at a specified rate using a number of connection types and protocols, including TCP, UDP, and unix domain sockets. The messages can be generated automatically (repeating the `PADD`string over and over), or read from a file or the standard input. When `loggen` finishes sending the messages, it displays the following statistics: * `average rate`: The average rate of the sent messages in messages/second. * `count`: The total number of messages sent. * `time`: The time required to send the messages in seconds. * `average message size`: The average size of the sent messages in bytes. * `bandwidth`: The average bandwidth used for sending the messages in kilobytes/second. ## Options * `--active-connections ` Number of connections `loggen` will use to send messages to the destination. This option is usable only when using TCP or TLS connections to the destination. Default value: 1 The `loggen` utility waits until every connection is established before starting to send messages. See also the `--idle-connections` option. * `--csv` or `-C` Send the statistics of the sent messages to `stdout` as CSV. This can be used for plotting the message rate. * `--client-port` Available in AxoSyslog 4.14 and later. Use the specified outbound port to connect to the server. Usable only for a single connection (when `--active-connections` is 1 and `--idle-connections` is not set). * `--dgram` or `-D` Use datagram socket (`UDP` or `unix-dgram`) to send the messages to the target. Requires the `--inet` option as well. * `dont-parse` or `-d` Do not parse the lines read from the input files, send them as received. * `--help` or `-h` Display a brief help message. * `--idle-connection ` Number of idle connections `loggen` will establish to the destination. Note that `loggen` will not send any messages on idle connections, but the connection is kept open using keep-alive messages. This option is usable only when using TCP or TLS connections to the destination. See also the `--active-connections` option. Default value: 0 * `--inet` or `-i` Use the TCP (by default) or UDP (when used together with the `--dgram` option) protocol to send the messages to the target. * `--interval ` or `-I ` The number of seconds `loggen` will run. Default value: 10 Note Note that when the `--interval` and `--number` are used together, `loggen` will send messages until the period set in `--interval` expires or the amount of messages set in `--number` is reached, whichever happens first. * `--ipv6` or `-6` Specify the destination using its IPv6 address. Note that the destination must have a real IPv6 address. * `--loop-reading` or `-l` Read the file specified in `--read-file` option in loop: loggen will start reading from the beginning of the file when it reaches the end of the file. * `--number ` or `-n ` Number of messages to generate. Note Note that when the `--interval` and `--number` are used together, `loggen` will send messages until the period set in `--interval` expires or the amount of messages set in `--number` is reached, whichever happens first. * `--no-framing` or `-F` Do not use the framing of the IETF-syslog protocol style, even if the `--syslog-proto` option is set. * `--perf` Disables rate limiting to send as many messages as possible. * `--permanent` or `-T` Keep sending logs indefinitely, without time limit. * `--quiet` or `-Q` Display statistics only when `loggen` is finished. If not set, the statistics are displayed every second. * `--rate ` or `-r ` The number of messages generated per second for every active connection. Default value: 1000. To disable rate limiting, use the `--perf` flag. If you want to change the message rate while loggen is running, send SIGUSR1 to double the message rate, or SIGUSR2 to halve it: `kill -USR1 ``kill -USR2 ` * `--read-file ` or `-R ` Read the messages from a file and send them to the target. See also the `--skip-tokens` option. Specify `-` as the input file to read messages from the standard input (stdio). Note that when reading messages from the standard input, `loggen` can only use a single thread. The `-R -`parameters must be placed at end of command, like: `loggen 127.0.0.1 1061 --read-file -` * `--reconnect` Try to reconnect when destination connections are lost. * `--sdata ` or `-p ` Send the argument of the `--sdata` option as the SDATA part of IETF-syslog (RFC5424 formatted) messages. Use it together with the `--syslog-proto` option. For example: `--sdata "[test name=\\"value\\"]` * `--size ` or `-s ` The size of a syslog message in bytes. Default value: 256. Minimum value: 127 bytes, maximum value: 8192 bytes. * `--skip-tokens ` Skip the specified number of space-separated tokens (words) at the beginning of every line. For example, if the messages in the file look like `foo bar message`, `--skip-tokens 2` skips the `foo bar` part of the line, and sends only the `message` part. Works only when used together with the `--read-file` parameter. Default value: 0 * `--stream` or `-S` Use a stream socket (TCP or unix-stream) to send the messages to the target. * `--syslog-proto` or `-P` Use the new IETF-syslog message format as specified in RFC5424. By default, loggen uses the legacy BSD-syslog message format (as described in RFC3164). See also the `--no-framing` option. * `--unix ` or `-x ` Use a UNIX domain socket to send the messages to the target. * `--use-ssl` or `-U` Use an SSL-encrypted channel to send the messages to the target. Note that it is not possible to check the certificate of the target, or to perform mutual authentication. * `--version` or `-V` Display version number of `syslog-ng`. ## Examples The following command generates 100 messages per second for ten minutes, and sends them to port 2010 of the localhost via TCP. Each message is 300 bytes long. Terminal window ``` loggen --stream --size 300 --rate 100 --interval 600 127.0.0.1 2010 ``` The following command is similar to the one above, but uses the UDP protocol. Terminal window ``` loggen --inet --dgram --size 300 --rate 100 --interval 600 127.0.0.1 2010 ``` Send a single message on TCP6 to the `::1` IPv6 address, port `1061:` Terminal window ``` loggen --stream --ipv6 --number 1 ::1 1061 ``` Send a single message on UDP6 to the `::1` IPv6 address, port `1061:` Terminal window ``` loggen --ipv6 --dgram --number 1 ::1 1061 ``` Send a single message using a unix domain-socket: Terminal window ``` loggen --unix --stream --number 1 ``` Read messages from the standard input (`stdio`) and send them to the localhost: Terminal window ``` loggen 127.0.0.1 1061 --stream --read-file - ``` ## Files `/opt/syslog-ng/bin/loggen` ## See also [syslog-ng.conf.5]() ## Getting help * The up-to-date documentation of AxoSyslog is available on the [AxoSyslog documentation site](). * For news and notifications about AxoSyslog, visit the [Axoflow blog](). * If you want to contact the developers directly to help with problems or report issues, contact us on [Discord]() or [GitHub](). This manual page is maintained by [Axoflow]() Last modified May 20, 2026: [Start reusing inlined chunks, part 1 (5255035b)]()