Manpage of IPTABLES
This specifies the netlink group (1-32) to which the packet is sent. Default value is 1.
--ulog-prefix prefix
Prefix log messages with the specified prefix; up to 32 characters long, and useful for
distinguishing messages in the logs.
--ulog-cprange size
Number of bytes to be copied to userspace. A value of 0 always copies the entire packet,
regardless of its size. Default is 0.
--ulog-qthreshold size
Number of packet to queue inside kernel. Setting this value to, e.g. 10 accumulates ten packets
inside the kernel and transmits them as one netlink multipart message to userspace. Default is 1
(for backwards compatibility).
TCPMSS
This target allows to alter the MSS value of TCP SYN packets, to control the maximum size for that
connection (usually limiting it to your outgoing interface's MTU minus 40). Of course, it can only be used
in conjunction with -p tcp.
This target is used to overcome criminally braindead ISPs or servers which block ICMP Fragmentation
Needed packets. The symptoms of this problem are that everything works fine from your Linux
firewall/router, but machines behind it can never exchange large packets:
1) Web browsers connect, then hang with no data received.
2) Small mail works fine, but large emails hang.
3) ssh works fine, but scp hangs after initial handshaking.
Workaround: activate this option and add a rule to your firewall configuration like:
iptables -A FORWARD -p tcp --tcp-flags SYN,RST SYN \
-j TCPMSS --clamp-mss-to-pmtu
--set-mss value
Explicitly set MSS option to specified value.
--clamp-mss-to-pmtu
Automatically clamp MSS value to (path_MTU - 40).
These options are mutually exclusive.
DSCP
http://www.iptablesrocks.org/syntax/man_iptables.htm (16 of 20) [2/13/2004 8:04:51 PM]
