Subject: SYN cookie firewall
To: tech-net@netbsd.org <tech-net@netbsd.org>
From: suxm <suxm@gnuchina.org>
List: tech-net
Date: 04/20/2001 06:49:03
hello, everyone.
Please think over the following figure.
client NetBSD Firewall server
------ ---------- ------
1. SYN----------- - - - - - - - - - ->
2. <------------SYN-ACK(cookie)
3. ACK----------- - - - - - - - - - ->
4. - - - - - - -SYN--------------->
5. <- - - - - - - - - ------------SYN-ACK
6. - - - - - - -ACK--------------->
7. -----------> relay the ------->
<----------- connection <-------
1. A SYN is sent from C(client) to S(server)
2. The firewall acts as S to respond a SYN-ACK with SYN=
cookie.
3. C send the ACK. Then the connection should be established.
4. The firewall acts as C to send a SYN to S.
5. S repond the SYN to C.
6. The firewall acts as C to send the ACK. Then the=
connection
is established.
7. The firewall relays data between C and S.
If SYN cookie is implemented in NetBSD, it can be used to protect=
server in the LAN.
I want to implement this scheme on NetBSD, and am finding someone=
who is interested in it.
Any suggestions will be appreciated.
Regards.
sincerely yours
suxm
suxm@gnuchina.org
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