[quagga-users 14996] Re: Which part of the kernel calculate the OSPF header checksum?

Matthias Ferdinand mf at 14v.de
Mon Nov 19 16:27:06 GMT 2018


On Sun, Nov 18, 2018 at 12:00:02PM +0000, quagga-users-request at lists.quagga.net wrote:
> Message: 1
> Date: Sat, 17 Nov 2018 21:57:33 +0800 (GMT+08:00)
> From: yanhc519 <yanhc519 at 163.com>
> To: "quagga-users at lists.quagga.net" <quagga-users at lists.quagga.net>
> Subject: [quagga-users 14995] Which part of the kernel calculate the
> 	OSPF	header checksum?
> Message-ID: <6344384f.8712.16721f65ff4.Coremail.yanhc519 at 163.com>
> Content-Type: text/plain; charset="utf-8"
> 
> Hi, everyone!
> 
> 
> In line 1649 of ospf6_message.c (\quagga-1.2.4\ospf6d), it says that "/* checksum is calculated by kernel */" as following.  I am wondering which part of the kernel calculate the OSPF header checksum? In Sockets layer or IPv6 layer? And in which file of what kernel?
> 
> 
>   /* fill OSPF header */
>   oh->version = OSPFV3_VERSION;
>   /* message type must be set before */
>   /* message length must be set before */
>   oh->router_id = oi->area->ospf6->router_id;
>   oh->area_id = oi->area->area_id;
>   /* checksum is calculated by kernel */
>   oh->instance_id = oi->instance_id;
>   oh->reserved = 0;
> 
> 
> Thanks in advance!
> 
> 
> Regards, 
> yanhc

Hm, I don't remember the kernel meddling inside user space packets.
Perhaps the comment is meant instead for authentication of OSPFv3
packets, as the protocol does not offer the simple auth mechanism as
with OSPFv2. With v3, you have to resort to IPsec for authentication.

Regards
Matthias


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