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-rw-r--r--tcpdump.1.in10
1 files changed, 10 insertions, 0 deletions
diff --git a/tcpdump.1.in b/tcpdump.1.in
index 5373ac0e..2056d0c9 100644
--- a/tcpdump.1.in
+++ b/tcpdump.1.in
@@ -1002,6 +1002,16 @@ tcpdump 'tcp[tcpflags] & (tcp-syn|tcp-fin) != 0 and not src and dst net \fIlocal
.fi
.RE
.LP
+To print the TCP packets with flags RST and ACK both set.
+(i.e. select only the RST and ACK flags in the flags field, and if the result
+is "RST and ACK both set", match)
+.RS
+.nf
+.B
+tcpdump 'tcp[tcpflags] & (tcp-rst|tcp-ack) == (tcp-rst|tcp-ack)'
+.fi
+.RE
+.LP
To print all IPv4 HTTP packets to and from port 80, i.e. print only
packets that contain data, not, for example, SYN and FIN packets and
ACK-only packets. (IPv6 is left as an exercise for the reader.)