1 These extensions can be used if `\-\-protocol tcp' is specified. It
2 provides the following options:
4 [\fB!\fP] \fB\-\-source\-port\fP,\fB\-\-sport\fP \fIport\fP[\fB:\fP\fIport\fP]
5 Source port or port range specification. This can either be a service
6 name or a port number. An inclusive range can also be specified,
7 using the format \fIfirst\fP\fB:\fP\fIlast\fP.
8 If the first port is omitted, "0" is assumed; if the last is omitted,
10 If the first port is greater than the second one they will be swapped.
13 is a convenient alias for this option.
15 [\fB!\fP] \fB\-\-destination\-port\fP,\fB\-\-dport\fP \fIport\fP[\fB:\fP\fIport\fP]
16 Destination port or port range specification. The flag
18 is a convenient alias for this option.
20 [\fB!\fP] \fB\-\-tcp\-flags\fP \fImask\fP \fIcomp\fP
21 Match when the TCP flags are as specified. The first argument \fImask\fP is the
22 flags which we should examine, written as a comma-separated list, and
23 the second argument \fIcomp\fP is a comma-separated list of flags which must be
25 .BR "SYN ACK FIN RST URG PSH ALL NONE" .
28 iptables \-A FORWARD \-p tcp \-\-tcp\-flags SYN,ACK,FIN,RST SYN
30 will only match packets with the SYN flag set, and the ACK, FIN and
33 [\fB!\fP] \fB\-\-syn\fP
34 Only match TCP packets with the SYN bit set and the ACK,RST and FIN bits
35 cleared. Such packets are used to request TCP connection initiation;
36 for example, blocking such packets coming in an interface will prevent
37 incoming TCP connections, but outgoing TCP connections will be
39 It is equivalent to \fB\-\-tcp\-flags SYN,RST,ACK,FIN SYN\fP.
40 If the "!" flag precedes the "\-\-syn", the sense of the
43 [\fB!\fP] \fB\-\-tcp\-option\fP \fInumber\fP
44 Match if TCP option set.