Hello Vincent Hanquez <[EMAIL PROTECTED]>, But this option seems to bring some side-effect. Is there any alternative?
tcp_syncookies - BOOLEAN Only valid when the kernel was compiled with CONFIG_SYNCOOKIES Send out syncookies when the syn backlog queue of a socket overflows. This is to prevent against the common 'syn flood attack' Default: FALSE Note, that syncookies is fallback facility. It MUST NOT be used to help highly loaded servers to stand against legal connection rate. If you see synflood warnings in your logs, but investigation shows that they occur because of overload with legal connections, you should tune another parameters until this warning disappear. See: tcp_max_syn_backlog, tcp_synack_retries, tcp_abort_on_overflow. syncookies seriously violate TCP protocol, do not allow to use TCP extensions, can result in serious degradation of some services (f.e. SMTP relaying), visible not by you, but your clients and relays, contacting you. While you see synflood warnings in logs not being really flooded, your server is seriously misconfigured. On Tue, 7 May 2002 17:39:12 +0200 Vincent Hanquez <[EMAIL PROTECTED]> wrote: > On Tue, May 07, 2002 at 10:26:43PM +0800, Patrick Hsieh wrote: > > Hello list, > > > > Is there anyone having any suggestion to tune the /proc/sys/net/ipv4/* > > to avoid tcp syn flood attack? > > there a kernel option "IP: TCP syncookie support" to do that > you can activate it with : > > echo 1 > /proc/sys/net/ipv4/tcp_syncookies > > hope it helps > > -- > Tab > > > -- > To UNSUBSCRIBE, email to [EMAIL PROTECTED] > with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED] -- Patrick Hsieh <[EMAIL PROTECTED]> GPG public key http://pahud.net/pubkeys/pahudatpahud.gpg -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]