ref: a078bdb66a95b9d604cfc0ba4122feec2e040c68
dir: /sys/man/3/sdp/
.TH SDP 3 .SH NAME sdp \- secure datagram protocol .SH SYNOPSIS .nf .B bind -a #E\fIspec\fP /net .sp 0.3v .B /net/sdp/clone .B /net/sdp/log .BI /net/sdp/ n .BI /net/sdp/ n /data .BI /net/sdp/ n /control .BI /net/sdp/ n /ctl .BI /net/sdp/ n /rstats .BI /net/sdp/ n /stats .BI /net/sdp/ n /status \&... .fi .SH DESCRIPTION The .I sdp device provides the interface to the Secure Datagram Protocol (SDP). SDP (un)compresses and (de-)encrypts packets. .I 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. .PP The top level directory contains a .B clone file, a .B log file, and subdirectories numbered from zero to the number of connections opened for this protocol. .PP Opening the .B clone file reserves a connection. The file descriptor returned from the .IR open (2) will point to the control file, .BR ctl , of the newly allocated connection. Reading .B 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. .PP A connection is controlled by writing text strings to the associated .B ctl file. After a connection has been established data may be read from and written to .BR data . A connection can be actively established using the .B connect message (see also .IR dial (2)). A connection can be established passively by first using an .B announce message (see .IR dial (2)) to bind to a local port and then opening the .B listen file (see .IR dial (2)) to receive incoming calls. .PP The following control messages are supported: .TF "outsecret \fIsecret .PD .TP .BI accept " file" Accept an incoming encrypted connection on .IR file , typically a .B data file. .TP .BI dial " file" Initiate a new encrypted connection on .IR file , typically a UDP .B data file. .TP .BI drop " permil" Randomly drop approximately one of every .I permil output packets, thus simulating network errors. .TP .BI cipher " algorithm" Use ciphering .IR algorithm ; choices are .LR null , .LR des_56_cbc , .LR rc4_128 , and .LR rc4_256 . .TP .BI auth " algorithm" Use authentication .IR algorithm ; choices are .LR null , .LR hmac_sha1_96 , and .LR hmac_md5_96 . .TP .BI comp " algorithm" Use compression .IR algorithm ; choices are .L null and .LR thwack . .TP .BI insecret " secret" Use .I secret to decrypt incoming packets. .TP .BI outsecret " secret" Use .I secret to encrypt outgoing packets. . .SH "SEE ALSO" .IR dial (2), .IR ip (3) .br .IR "Robust Data Compression of Network Packets" , Sean Dorward and Sean Quilan, Bell Labs, Lucent Technologies, .BR http://plan9.bell-labs.com/who/seanq/networkcomp.pdf . .SH SOURCE .B /sys/src/9/port/devsdp.c