netdev - Re: [PATCH net-next v2] ipv4: Add support to disable icmp timestamp

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Message-Id: <20190513.091622.1327750308553784712.davem@davemloft.net>
Date:   Mon, 13 May 2019 09:16:22 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     chenweilong@...wei.com
Cc:     kuznet@....inr.ac.ru, yoshfuji@...ux-ipv6.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH net-next v2] ipv4: Add support to disable icmp timestamp

From: Weilong Chen <chenweilong@...wei.com>
Date: Mon, 13 May 2019 21:28:57 +0800

> The remote host answers to an ICMP timestamp request.
> This allows an attacker to know the time and date on your host.
> 
> This path is an another way contrast to iptables rules:
> iptables -A input -p icmp --icmp-type timestamp-request -j DROP
> iptables -A output -p icmp --icmp-type timestamp-reply -j DROP
> 
> Default is enabled.
> 
> enable:
> 	sysctl -w net.ipv4.icmp_timestamp_enable=1
> disable
> 	sysctl -w net.ipv4.icmp_timestamp_enable=0
> testing:
> 	hping3 --icmp --icmp-ts -V $IPADDR
> 
> Signed-off-by: Weilong Chen <chenweilong@...wei.com>

Premise is wrong, understanding of what ICMP timestamp value actually
is is inaccurate, and the solution is wrong.

No way I am applying this, sorry.