From 48b1de4c110a7afa4b85862f6c75af817db26fad Mon Sep 17 00:00:00 2001 From: Patrick McHardy Date: Tue, 27 Aug 2013 08:50:14 +0200 Subject: netfilter: add SYNPROXY core/target Add a SYNPROXY for netfilter. The code is split into two parts, the synproxy core with common functions and an address family specific target. The SYNPROXY receives the connection request from the client, responds with a SYN/ACK containing a SYN cookie and announcing a zero window and checks whether the final ACK from the client contains a valid cookie. It then establishes a connection to the original destination and, if successful, sends a window update to the client with the window size announced by the server. Support for timestamps, SACK, window scaling and MSS options can be statically configured as target parameters if the features of the server are known. If timestamps are used, the timestamp value sent back to the client in the SYN/ACK will be different from the real timestamp of the server. In order to now break PAWS, the timestamps are translated in the direction server->client. Signed-off-by: Patrick McHardy Tested-by: Martin Topholm Signed-off-by: Jesper Dangaard Brouer Signed-off-by: Pablo Neira Ayuso --- include/uapi/linux/netfilter/xt_SYNPROXY.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) create mode 100644 include/uapi/linux/netfilter/xt_SYNPROXY.h (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/netfilter/xt_SYNPROXY.h b/include/uapi/linux/netfilter/xt_SYNPROXY.h new file mode 100644 index 000000000000..2d59fbaa93c6 --- /dev/null +++ b/include/uapi/linux/netfilter/xt_SYNPROXY.h @@ -0,0 +1,16 @@ +#ifndef _XT_SYNPROXY_H +#define _XT_SYNPROXY_H + +#define XT_SYNPROXY_OPT_MSS 0x01 +#define XT_SYNPROXY_OPT_WSCALE 0x02 +#define XT_SYNPROXY_OPT_SACK_PERM 0x04 +#define XT_SYNPROXY_OPT_TIMESTAMP 0x08 +#define XT_SYNPROXY_OPT_ECN 0x10 + +struct xt_synproxy_info { + __u8 options; + __u8 wscale; + __u16 mss; +}; + +#endif /* _XT_SYNPROXY_H */ -- cgit v1.2.3