tcprules(1) - phpMan
tcprules(1) General Commands Manual tcprules(1)
tcprules - compiles rules for tcpserver(1).
tcprules cdb tmp
tcpserver(1) optionally follows rules to decide whether a TCP connection is acceptable.
For example, the rule
prohibits connections from IP address 18.104.22.168.
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 atomi‐
cally. 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.
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.
tcpserver(1) looks for rules with various addresses:
1. $TCPREMOTEINFO@$TCPREMOTEIP, if $TCPREMOTEINFO is set;
2. $TCPREMOTEINFO@=$TCPREMOTEHOST, if $TCPREMOTEINFO is set and $TCPREMOTEHOST is set;
4. =$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 AT 127.1:first
If $TCPREMOTEIP is 10.119.75.38, tcpserver(1) will follow the third instructions.
If $TCPREMOTEIP is 22.214.171.124, tcpserver(1) will follow the second instructions.
If $TCPREMOTEIP is 127.0.0.1 and $TCPREMOTEINFO is bill, tcpserver(1) will follow the
If $TCPREMOTEIP is 127.0.0.1 and $TCPREMOTEINFO is joe, tcpserver(1) will follow the first
You can use tcprulescheck(1) to see how tcpserver will interpret rules in cdb.
tcprules treats 126.96.36.199-53:ins as an abbreviation for the rules 188.8.131.52:ins,
184.108.40.206:ins, and so on up through 220.127.116.11:ins. Similarly, 10.2-3.:ins is an abbreviation
for 10.2.:ins and 10.3.:ins.
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
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,
adds an environment variable $RELAYCLIENT with value @fix.me. The quotes may be replaced
by any repeated character:
Any number of variables may be listed:
tcpserver(1), tcprulescheck(1), argv0(1), fixcrio(1), recordio(1), rblsmtpd(1), tcp‐
client(1), who@(1), date@(1), finger@(1), http@(1), tcpcat(1), mconnect(1), tcp-environ(5)