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)