NAME

sdp − secure datagram protocol

SYNOPSIS

­bind -a #Espec /net
­/net/sdp/clone
­/net/sdp/log
/net/sdp/n
/net/sdp/n/data
/net/sdp/n/control
/net/sdp/n/ctl
/net/sdp/n/rstats
/net/sdp/n/stats
/net/sdp/n/status
...

DESCRIPTION

The ­sdp device provides the interface to the Secure Datagram Protocol (SDP).  SDP (un)compresses and (de-)encrypts packets.  ­Spec is an integer 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 subdirectories numbered from zero to the number of connections opened for this protocol. 

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 representing 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 file Accept an incoming encrypted connection on file, typically a ­data file. 

dial file Initiate a new encrypted connection on file, typically a UDP ­data file. 

drop permil Randomly drop approximately one of every ­permil output packets, thus simulating network errors. 

cipher algorithm Use ciphering algorithm; choices are null, des_56_cbc, rc4_128, and rc4_256. 

auth algorithm Use authentication algorithm; choices are null, hmac_sha1_96, and hmac_md5_96. 

comp algorithm Use compression algorithm; choices are ­null and thwack. 

insecret secret Use ­secret to decrypt incoming packets. 

outsecret secret Use ­secret to encrypt outgoing packets. 

SEE ALSO

dial(2), ip(3)
Robust Data Compression of Network Packets, Sean Dorward and Sean Quilan, Bell Labs, Lucent Technologies, http://plan9.bell-labs.com/who/seanq/networkcomp.pdf. 

SOURCE

­/sys/src/9/port/devsdp.c

Plan 9  —  October 02, 2013