NAME

       tcprules - compiles rules for tcpserver(1).

SYNOPSIS

       tcprules cdb tmp

DESCRIPTION

       tcpserver(1)  optionally  follows  rules to decide whether a TCP connection is acceptable.
       For example, the rule

              18.23.0.32:deny

       prohibits connections from IP address 18.23.0.32.

       tcprules reads rules from its standard input and writes them into cdb in a  binary  format
       suited for quick access by tcpserver(1).

       tcprules  can  be  used  while  tcpserver(1)  is  running.  It ensures that cdb is updated
       atomically. It does this by first writing the rules to tmp and then moving tmp on  top  of
       cdb.   If tmp already exists, it is destroyed. The directories containing cdb and tmp must
       be writable to tcprules; they must also be on the same filesystem.

       If there is a problem with the input or with tmp, tcprules complains and leaves cdb alone.

       The binary cdb format is portable across machines.

RULE FORMAT

       A rule is one line. A file containing rules may also  contain  comments:  lines  beginning
       with # are ignored.

       Each  rule contains an address, a colon, and a list of instructions, with no extra spaces.
       When tcpserver(1) receives a connection from that address, it follows the instructions.

ADDRESSES

       tcpserver(1) looks for rules with various addresses:

       1.     $TCPREMOTEINFO@$TCPREMOTEIP, if $TCPREMOTEINFO is set;

       2.     $TCPREMOTEINFO@=$TCPREMOTEHOST, if $TCPREMOTEINFO is set and $TCPREMOTEHOST is set;

       3.     $TCPREMOTEIP;

       4.     =$TCPREMOTEHOST, if $TCPREMOTEHOST is set;

       5.     shorter and shorter prefixes of $TCPREMOTEIP ending with a dot;

       6.     shorter and shorter suffixes of $TCPREMOTEHOST starting with a dot, preceded by  =,
              if $TCPREMOTEHOST is set;

       7.     =, if $TCPREMOTEHOST is set; and finally

       8.     the empty string.

       tcpserver(1) uses the first rule it finds. You should use the -p option to tcpserver(1) if
       you rely on $TCPREMOTEHOST here.

       For example, here are some rules:

            joe@127.0.0.1:first
            18.23.0.32:second
            :third
            127.:fourth

       If $TCPREMOTEIP is 10.119.75.38, tcpserver(1) will follow the third instructions.

       If $TCPREMOTEIP is 18.23.0.32, tcpserver(1) will follow the second instructions.

       If $TCPREMOTEIP is 127.0.0.1 and $TCPREMOTEINFO is  bill,  tcpserver(1)  will  follow  the
       fourth instructions.

       If $TCPREMOTEIP is 127.0.0.1 and $TCPREMOTEINFO is joe, tcpserver(1) will follow the first
       instructions.

       You can use tcprulescheck(1) to see how tcpserver will interpret rules in cdb.

ADDRESS RANGES

       tcprules  treats  1.2.3.37-53:ins  as  an  abbreviation  for   the   rules   1.2.3.37:ins,
       1.2.3.38:ins, and so on up through 1.2.3.53:ins. Similarly, 10.2-3.:ins is an abbreviation
       for 10.2.:ins and 10.3.:ins.

INSTRUCTIONS

       The instructions in a rule must begin with either allow or deny. deny  tells  tcpserver(1)
       to drop the connection without running anything. For example, the rule

              :deny

       tells tcpserver(1) to drop all connections that aren't handled by more specific rules.

       The  instructions  may  continue  with  some  environment  variables, in the form var="x".
       tcpserver(1) adds an environment variable $var with value x. For example,

              10.0.:allow,RELAYCLIENT="@fix.me"

       adds an environment variable $RELAYCLIENT with value @fix.me. The quotes may  be  replaced
       by any repeated character:

              10.0.:allow,RELAYCLIENT=/@fix.me/

       Any number of variables may be listed:

              127.0.0.1:allow,RELAYCLIENT="",TCPLOCALHOST="movie.edu"

SEE ALSO

       tcpserver(1),    tcprulescheck(1),   argv0(1),   fixcrio(1),   recordio(1),   rblsmtpd(1),
       tcpclient(1),  who@(1),  date@(1),  finger@(1),  http@(1),  tcpcat(1),  mconnect(1),  tcp-
       environ(5)

       http://cr.yp.to/ucspi-tcp.html

                                                                                      tcprules(1)