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Diffstat (limited to 'extensions/libip6t_REJECT.man')
-rw-r--r-- | extensions/libip6t_REJECT.man | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/extensions/libip6t_REJECT.man b/extensions/libip6t_REJECT.man index 0030a51f..e68d6f03 100644 --- a/extensions/libip6t_REJECT.man +++ b/extensions/libip6t_REJECT.man @@ -30,3 +30,24 @@ TCP RST packet to be sent back. This is mainly useful for blocking hosts (which won't accept your mail otherwise). \fBtcp\-reset\fP can only be used with kernel versions 2.6.14 or later. +.PP +\fIWarning:\fP You should not indiscriminately apply the REJECT target to +packets whose connection state is classified as INVALID; instead, you should +only DROP these. +.PP +Consider a source host transmitting a packet P, with P experiencing so much +delay along its path that the source host issues a retransmission, P_2, with +P_2 being successful in reaching its destination and advancing the connection +state normally. It is conceivable that the late-arriving P may be considered +not to be associated with any connection tracking entry. Generating a reject +response for a packet so classed would then terminate the healthy connection. +.PP +So, instead of: +.PP +\-A INPUT ... \-j REJECT +.PP +do consider using: +.PP +\-A INPUT ... \-m conntrack \-\-ctstate INVALID \-j DROP +.br +\-A INPUT ... \-j REJECT |