@node Use cases
@unnumbered Use cases
+See also this page @ref{Сценарии, on russian}.
+
@menu
* Occasional connection to mail server: UsecaseMail.
* Lightweight fast POP3/IMAP4 replacement: UsecasePOP.
* Unreliable/expensive communication link: UsecaseUnreliable.
* Slow/expensive link for high-volume data, bad QoS: UsecaseQoS.
* Extreme terrestrial environments, no link: UsecaseNoLink.
+* One-way broadcasting communications: UsecaseBroadcast.
* Private, isolated MitM/Sybil-resistant networks: UsecaseF2F.
* Highly secure isolated air-gap computers: UsecaseAirgap.
* Network censorship bypassing, health: UsecaseCensor.
@url{https://en.wikipedia.org/wiki/KISS_principle, KISS}!
Just tell both of your Postfixes (on the server and notebook) to drop
-email as a mail via NNCP (@ref{nncp-mail}) to specified node. This is
+email as a mail via NNCP (@ref{nncp-exec}) to specified node. This is
done similarly as with UUCP and as written in
@url{http://www.postfix.org/UUCP_README.html, Postfix documentation}.
@ref{nncp-daemon} can be connected with @ref{nncp-caller} for a long
time -- it can create TCP connection that lasts for many hours. When
-SMTP server receives mail, it will call @ref{nncp-mail} creating an
+SMTP server receives mail, it will call @ref{nncp-exec} creating an
outbound encrypted packet. Daemon checks outbound directory each second
and immediately sends notification about undelivered packets to remote
side, that also downloads it at once.
messages is problematic to retrieve. Moreover, each disconnect leads to
the same data retransmission again, that can not be afforded sometimes.
-Just send your @ref{nncp-mail, mail} and @ref{nncp-file, files} through
+Just send your @ref{nncp-exec, mail} and @ref{nncp-file, files} through
NNCP. You can use either offline delivery methods -- read about them in
the next section, or you can use included NNCP @ref{nncp-daemon, TCP
daemon}.
possibility to transfer virtually any volumes using small capacity
storages.
+You can also use CD-ROM and tape drives:
+
+@verbatim
+% nncp-bundle -tx bob | cdrecord -tao -
+% nncp-bundle -tx bob | dd of=/dev/sa0 bs=10240
+@end verbatim
+
@node UsecaseNoLink
@section Extreme terrestrial environments, no link
media for transferring packets to other nodes.
Assume that you send two files to @emph{bob} node. Insert USB storage
-device, mount it and run @ref{nncp-xfer}:
+device (SD is preferable!), mount it and run @ref{nncp-xfer}:
@verbatim
% nncp-xfer -node bob /media/usbstick
@end verbatim
to copy all outbound packets related to @emph{bob}. Use @option{-mkdir}
-option to create related directory on USB storage if they are missing
+option to create related directory on USB/SD storage if they are missing
(for example when running for the first time).
If you use single storage device to transfer data both to @emph{bob} and
further processing. @command{nncp-xfer} is the only command used with
removable devices.
+@node UsecaseBroadcast
+@section One-way broadcasting communications
+
+Sometimes you have got high-bandwidth but unidirectional link, for
+example, satellite's broadcasting signal. You are not able to use online
+@ref{Sync, synchronization protocol} because it requires mutual interaction.
+
+You can use @ref{Bundles, bundles} and stream them above. They are just
+a sequence of @ref{Encrypted, encrypted packets} you can catch on.
+
+@verbatim
+% nncp-bundle -tx alice bob eve ... | command to send broadcast
+% command to receive broadcast | nncp-bundle -rx
+@end verbatim
+
+With built-in packet duplicates detection ability, you can retransmit
+your broadcasts from time to time, to increase chances the recipient
+will catch them by regular stream listening.
+
@node UsecaseF2F
@section Private, isolated MitM/Sybil-resistant networks
only choice you can afford. Computer without any modems, wired and
wireless networks. Obviously the only possibility to exchange mail and
files is to use physically removable storage devices like CD-ROM, hard
-drive, tape and USB flash drives (worst choice, due to those devices
-complexity).
+drive, SD, tape and USB flash drives (@strong{worst} choice, due to
+those devices complexity).
Presumably you have got another own hop before that computer: another
intermediate node which performs basic verification of retrieved storage