|-t n||Change the timeout to n seconds.|
If the $RBLSMTPD environment variable is set and is nonempty,
rblsmtpd blocks mail. It uses $RBLSMTPD as an error message for the client. Normally
rblsmtpd runs under
you can use
to set $RBLSMTPD for selected clients.
If $RBLSMTPD is set and is empty, rblsmtpd does not block mail.
If $RBLSMTPD is not set, rblsmtpd looks up $TCPREMOTEIP in the RBL, and blocks mail if $TCPREMOTEIP is listed. tcpserver sets up $TCPREMOTEIP as the IP address of the remote host.
|-r base||Use base as an RBL source. An IP address a.b.c.d is listed by that source if d.c.b.a.base has a TXT record. rblsmtpd uses the contents of the TXT record as an error message for the client.|
|-a base||Use base as an anti-RBL source. An IP address a.b.c.d is anti-listed by that source if d.c.b.a.base has an A record. In this case rblsmtpd does not block mail.|
You may supply any number of
rblsmtpd tries each source in turn until it finds one that lists or anti-lists $TCPREMOTEIP. It also tries an RBL source of rbl.maps.vix.com if you do not supply any
-r options. See http://maps.vix.com/rbl/ for more information about rbl.maps.vix.com.
If you want to run your own RBL source or anti-RBL source for rblsmtpd, you can use rbldns from the DNScache (djbdns) package.
Normally, if $RBLSMTPD is set,
rblsmtpd uses a 451 error code in its limited SMTP conversation. This tells legitimate clients to try again later. It gives innocent relay operators a chance to see the problem, prohibit relaying, get off the RBL, and get the mail delivered.
However, if $RBLSMTPD begins with a hyphen, rblsmtpd removes the hyphen and uses a 553 error code. This tells legitimate clients to bounce the message immediately.
There are several error-handling options for RBL lookups:
|-B||(Default.) Use a 451 error code for IP addresses listed in the RBL.|
|-b||Use a 553 error code for IP addresses listed in the RBL.|
|-C||(Default.) Handle RBL lookups in a fail-open mode. If an RBL lookup fails temporarily, assume that the address is not listed; if an anti-RBL lookup fails temporarily, assume that the address is anti-listed. Unfortunately, a knowledgeable attacker can force an RBL lookup or an anti-RBL lookup to fail temporarily, so that his mail is not blocked.|
|-c||Handle RBL lookups in a fail-closed mode. If an RBL lookup fails temporarily, assume that the address is listed (but use a 451 error code even with -b). If an anti-RBL lookup fails temporarily, assume that the address is not anti-listed (but use a 451 error code even if a subsequent RBL lookup succeeds with -b). Unfortunately, this sometimes delays legitimate mail.|
tcpserver(1), tcprules(1), tcprulescheck(1), fixcrio(1), recordio(1), rblsmtpd(1), tcpclient(1), who@(1), date@(1), finger@(1), http@(1), tcpcat(1), mconnect(1), tcp-environ(5)