SDP(3)SDP(3)NAMEsdp - secure datagram protocol
bind -a #Espec /net
The sdp device provides the interface to the Secure Datagram Protocol
(SDP). SDP (un)compresses and (de-)encrypts packets. Spec is an inte‐
ger from 0 to 15 identifying a stack. Each stack is independent of all
others: the only information transfer between them is via programs that
mount multiple stacks. Normally a system uses only one stack. However
multiple stacks can be used for debugging new networks or implementing
firewalls or proxy services.
The top level directory contains a clone file, a log file, and subdi‐
rectories numbered from zero to the number of connections opened for
Opening the clone file reserves a connection. The file descriptor
returned from the open(2) will point to the control file, ctl, of the
newly allocated connection. Reading ctl returns a text string repre‐
senting the number of the connection. Connections may be used either
to listen for incoming calls or to initiate calls to other machines.
A connection is controlled by writing text strings to the associated
ctl file. After a connection has been established data may be read
from and written to data. A connection can be actively established
using the connect message (see also dial(2)). A connection can be
established passively by first using an announce message (see dial(2))
to bind to a local port and then opening the listen file (see dial(2))
to receive incoming calls.
The following control messages are supported:
Accept an incoming encrypted connection on file, typically a
Initiate a new encrypted connection on file, typically a UDP
Randomly drop approximately one of every permil output packets,
thus simulating network errors.
Use ciphering algorithm; choices are and
Use authentication algorithm; choices are and
Use compression algorithm; choices are and
Use secret to decrypt incoming packets.
Use secret to encrypt outgoing packets.
SEE ALSOdial(2), ip(3)
Robust Data Compression of Network Packets, Sean Dorward and Sean
Quilan, Bell Labs, Lucent Technologies, http://plan9.bell-