Table of Contents

Introduction #

This is a simple server for syslog.

It supports incoming connection via udp (514) or tcp (601) without tls.

It listens on all interfaces but can’t use both protocols at the same time (you should run 2 servers).

Build #

cargo build --release

If you don’t want or can’t build the executable, you can download it in the release tab.

Run #

If builded with cargo:

sudo target/release/syslogd-rust --help

If downloaded:

sudo syslogd-rust --help

Log to file #

If you want to log to a file you can redirect the output or use a command like tee:

sudo syslogd-rust | tee -a log.txt

Send a log message #

In linux you can use the logger command:

logger -is -n 127.0.0.1 this message is sent with udp

logger -is --tcp -n 127.0.0.1 this message is sent with tcp

“The Flow” #

Depending on the flag used, the port is bound and the process waits for connections. For udp it defines the socket (with the bind of the port) and enters an infinite loop in which every incoming connection is accepted. After which the transmitted content is passed to the print_message() function, which takes care of parsing and printing the payload.

For tcp instead a listener is created, which is an infinite iterator. A for loop loops through all incoming connections. Each connection is then accepted and read to extract its payload. As before it is passed to print_message().

print_message() uses syslog_loose for parsing and then has a series of conditional prints (only print if the value is present).

Using the --raw flag you can see the original payload.

Clap is used for parsing command line arguments.

I don’t know why yet, but using tcp appends a \n to the end. This doesn’t happen with udp. To make the outputs equal I trim the last character if it’s a \n or \r.

All the connections should stop after sending a single packet (both udp and tcp), because the tcp listener, in its current implementation (done by me) can’t handle multiple reads on the same stream. This theoretically shouldn’t be a problem.

Syslogd server in Rust