duplicate

duplicate is a small utility tool that listen for an incoming udp stream and duplicates this stream to multiple remote destination. Optionally, duplicate can wait for a configured delay before starting duplicating the received packets.

usage:

$ duplicate config.toml

configuration

table [default]

• remote: tell duplicate to listen for UDP packets coming from remote address.
• nic: when duplicate subscribe to a multicast group for its incoming packets and that multiple interface are avaible on the server, the nic (network interface controller) tells duplicate the interface with the specified identifier. This option is not mandatory. Duplicate will chose the default network interface if the option is not set or let empty.

table [[route]]

• address: address (ip:port) of the remote host where duplicate has to forward the incoming stream.
• delay: delay (in millisecond) to wait before starting to forward the incoming stream. If the option is not set or set to 0, duplicate will not introduce any delay and will start to forward the incoming stream as soon as the first packet come in.
• buffer: size of the buffer to use when duplicate has to wait before forwarding the incoming stream. If the option is not set or set to 0, duplicate uses a default value of 8MB

⚠️ The value of the buffer option should be choosen carefully. Indeed, if the buffer size is too short and because it is implemented as ring buffer, it could seems that the delay option has no effect.

The best way to compute the "ideal" size for the buffer is:

buffer = (packet size * delay in seconds * number of packets per second) + extra margin

eg:
packet size       = 1316
delay             = 60s
number of packets = 100

buffer = 1316 * 60 * 100 = 7896000 bytes (~8MB)

example

# listen for UDP packets coming from remote address
remote = "127.0.0.1:11111"
nic    = "eth0"

[[route]]
# delay of 5s with buffer size of ~8KB
address = "239.192.0.1:22222"
delay   = 5000
buffer  = 8192

[[route]]
# delay of 1s with buffer size of ~1KB
address = "239.192.0.1:33333"
buffer  = 1024
delay   = 1000