man: Refer to pcap-filter(7) early. [skip ci]

diff --git a/tcpdump.1.in b/tcpdump.1.in
index 1e05d0bd2dfeb9ffc5d75d4647adae561d94dc0b..029bc39b8c67b53481ae696f3f981253e67d1fd2 100644 (file)
--- a/tcpdump.1.in
+++ b/tcpdump.1.in
@@ -157,7 +157,9 @@ tcpdump \- dump traffic on a network
 .SH DESCRIPTION
 .LP
 \fITcpdump\fP prints out a description of the contents of packets on a
-network interface that match the Boolean \fIexpression\fP; the
+network interface that match the Boolean \fIexpression\fP (see
+.BR pcap-filter (7)
+for the \fIexpression\fP syntax); the
 description is preceded by a time stamp, printed, by default, as hours,
 minutes, seconds, and fractions of a second since midnight.  It can also
 be run with the