Mailing List ecs-isp@2rosenthals.com Message #1311
Från: "Massimo S." <ecs-isp@2rosenthals.com> Meddelandehuvud
Oavkodat meddelande
Ämne: Re: [eCS-ISP] DDOS attacks and tcp/ip SYNCOOKIE flag
Datum: Thu, 5 Feb 2026 20:07:04 +0100
Till: eCS ISP Mailing List <ecs-isp@2rosenthals.com>

Il 04/02/2026 14:30, Ian Manners ha scritto:
Hi Massimo,

to mitigate the effects of DDOS attacks (eg. the ones on port 80 and 443) it is
suggested to turn ON syncookie tcp/ip flag.

syncookie is broken on OS/2's implementation, do not turn it on.

Cheers
Ian Manners

Hi Ian,

and there are no plans to fix this?

massimo

But i've realized that on eCS and AOS this parameter give a number of issues.

Clients start calling that images on websites do not load correctly or take
a lot of time to render/complete.

While i've also seen that turning ON this flag increase the instability
of the web server VM at the point that the entire OS can completely freeze
(this on eCS and AOS too).

The flag SYNATTACK seems to work properly instead, but SYNCOOKIE i guess
it's very bugged.


massimo

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