changing the ToS in IP Header

[Ashish Kulkarni]

as I mentioned earlier, I want to do it for all outgoing packets on an
interface, not on per socket basis. I actually was hoping that somene
would provide me pointers to where I should look in the source (me being a
newcomer to BSD as such) to implement a sysctl that will allow me to
change the tos, eg. "net.inet.ip.tos". I'd have prefered to use a packet
mangling firewall, but afaik there are none which do that so I'll have to
do it the hard way ;-)

Thanks,
Ashish


----- Original Message -----
From: "Jerry Toung" <jtoung at mindspring.com>
To: <ashish at symonds.net>; <freebsd-hackers at freebsd.org>
Sent: Monday, May 26, 2003 9:36 PM
Subject: Re: changing the ToS in IP Header


Ashish,
you can set the TOS bit when you create the socket in your program.


int fd, tos;
fd = socket(PF_INET, SOCK_DGRAM, 0)
tos=3;
setsockopt(fd,IPPROTO_IP,3, &tos, sizeof(tos))

On Monday 26 May 2003 07:21 am, Ashish Kulkarni wrote:
> Hello,
>
>
> Is there any way in which I can manipulate the Type of Service (TOS) byte
> in the IPv4 header? I need to set the TOS bits on all outgoing packets from
> my box to the ISP to a particular pattern (0x02), as otherwise the ISP does
> not forward packets. I have been able to do this in Linux using the
> iptables mangle table:
>
>
> http://www.tldp.org/LDP/nag2/x-087-2-firewall.tos.manipulation.html
>
>
> but am unable to find a similiar packet-mangling feature in the firewalls
> running on FreeBSD...there are rules for matching on TOS pattern, but not
> on TOS manipulation. Does anyone know of any tool which can do this?
>
>
> As an alternative solution, is there any way to set the default TOS via a
> sysctl interface (similiar to that of TTL, namely  net.inet.ip.ttl)? I'm
> planning to use this on my home box, so I have no problems in trying to
> patch and rebuild the kernel if I can get some feedback and/or tips on how
> to do so :-)
>
>
> Thanks,
> Ashish.
>
>
> ps: can you please CC any replies to me? thanks...
>-