npush and npoll are tools to quickly copy files over an IP LAN. npush
will send UDP multicast/broadcast packets to advertise that it is
willing to send files, npoll will look for these UDP packets and then
connect to the sending machine. The advantage is that you dont have to
type the name of the machine that you want to send data to, and you
dont have to type the name of the server.
Optionally, you can tell npoll the name of the server. This is useful
if the server is not in the same LAN.
If you do not give npush any arguments, it will copy stdin over the
network. npoll will in this case output the data to stdout. To make
this work in pipes, the diagnostic messages are now output on stderr.
npush will use TCP port 8002 for its connections and for the UDP
packets. npush will try to advertise using IPv6 multicast, but it will
fall back to IPv4 multicast and IPv4 broadcast (which was the only
option before version 1.0). Use the -b option to npush to make
sure that clients before version 1.0 can see the advertisements.
npush will call tar only after it has opened the connection. If you
forgot to specify and files or tried to send nonexistant files, tar
will spew out error messages. The peer will see no error messages!
No error detection, error recovery or even decent error messages.
The broadcast packets always go out over the network interface with the
default route. This means that your PPP dialin server will npush the
broadcast packets to the PPP interface. You can fix this by setting a
static route for destination 255.255.255.255 to the LAN interface.
Some routers are stupid enough to forward the broadcast packets.