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      1 This is used to send back an error packet in response to the matched
      2 packet: otherwise it is equivalent to
      3 .B DROP
      4 so it is a terminating TARGET, ending rule traversal.
      5 This target is only valid in the
      6 .BR INPUT ,
      7 .B FORWARD
      8 and
      9 .B OUTPUT
     10 chains, and user-defined chains which are only called from those
     11 chains.  The following option controls the nature of the error packet
     12 returned:
     13 .TP
     14 \fB\-\-reject\-with\fP \fItype\fP
     15 The type given can be
     16 \fBicmp\-net\-unreachable\fP,
     17 \fBicmp\-host\-unreachable\fP,
     18 \fBicmp\-port\-unreachable\fP,
     19 \fBicmp\-proto\-unreachable\fP,
     20 \fBicmp\-net\-prohibited\fP,
     21 \fBicmp\-host\-prohibited\fP or
     22 \fBicmp\-admin\-prohibited\fP (*)
     23 which return the appropriate ICMP error message (\fBport\-unreachable\fP is
     24 the default).  The option
     25 \fBtcp\-reset\fP
     26 can be used on rules which only match the TCP protocol: this causes a
     27 TCP RST packet to be sent back.  This is mainly useful for blocking 
     28 .I ident
     29 (113/tcp) probes which frequently occur when sending mail to broken mail
     30 hosts (which won't accept your mail otherwise).
     31 .PP
     32 (*) Using icmp\-admin\-prohibited with kernels that do not support it will result in a plain DROP instead of REJECT
     33