--- title: "The loggen manual page" url: "https://axoflow.com/docs/axosyslog-core/4.28/app-man-syslog-ng/loggen.1/" last_modified: "2026-09-23T14:09:57+02:00" --- > For the complete documentation index, see [llms.txt](https://axoflow.com/docs/axosyslog-core/4.28/llms.txt). # 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: ```shell 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. - `--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). - `--debug` Enable debug messages of `loggen`. - `--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-connections ` 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. - `--proxied []` or `-H []` Prepend a PROXY protocol header to the generated messages. The optional argument selects the version of the PROXY protocol: `1` or `2`. Default value: `1` Use the `--proxy-src-ip`, `--proxy-dst-ip`, `--proxy-src-port`, and `--proxy-dst-port` options to set the addresses in the header. - `--proxied-tls-passthrough` Send the PROXY protocol header before the encrypted payload. Use it together with the `--proxied` and `--use-ssl` options. - `--proxy-dst-ip ` The destination IP address to set in the PROXY protocol header. - `--proxy-dst-port ` The destination port to set in the PROXY protocol header. - `--proxy-src-ip ` The source IP address to set in the PROXY protocol header. - `--proxy-src-port ` The source port to set in the PROXY protocol header. - `--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 ` - `--rate-burst-start` Start sending messages at the full rate set in the `--rate` option, instead of ramping the rate up gradually. Useful for testing rate limiting. - `--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. ## 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. ```shell 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. ```shell 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:` ```shell loggen --stream --ipv6 --number 1 ::1 1061 ``` Send a single message on UDP6 to the `::1` IPv6 address, port `1061:` ```shell loggen --ipv6 --dgram --number 1 ::1 1061 ``` Send a single message using a unix domain-socket: ```shell loggen --unix --stream --number 1 ``` Read messages from the standard input (`stdio`) and send them to the localhost: ```shell loggen 127.0.0.1 1061 --stream --read-file - ``` ## Files `/opt/syslog-ng/bin/loggen` ## See also [syslog-ng.conf.5](https://axoflow.com/docs/axosyslog-core/app-man-syslog-ng/syslog-ng.conf.5/) ## Getting help - The up-to-date documentation of AxoSyslog is available on the [AxoSyslog documentation site](https://axoflow.com/docs/axosyslog-core/). - For news and notifications about AxoSyslog, visit the [Axoflow blog](https://axoflow.com/blog/). - If you want to contact the developers directly to help with problems or report issues, contact us on [Discord](https://discord.gg/583Z4wjem2) or [GitHub](https://github.com/axoflow/axosyslog/issues/). This manual page is maintained by [Axoflow](https://axoflow.com/) Last modified September 23, 2026: [Typo fixes (f8ce1864)](https://github.com/axoflow/axosyslog-core-docs/commit/f8ce1864cd0b21cc012d57c7dde41b8e37d8a58a)