> +	if (TCP_ECN_ALLOWED(tp)) {
> +		switch (iptos & IPTOS_ECN_MASK) {
> +		case IPTOS_ECN_CE:
> +			tp->t_flags |= TF_ECN_SND_ECE;
> +			tcpstat.tcps_ecn_ce++;
> +			break;
> +		case IPTOS_ECN_ECT0:
> +			tcpstat.tcps_ecn_ect++;
> +			break;
> +		case IPTOS_ECN_ECT1:
> +			/* XXX: ignore for now -- rpaulo */
> +			break;

Would it make sense to print a message to the console that a 
unsupported/not allowed option was used? FWIW, Solaris prints something 
like this (for something IPv6 related):

 	Jul 17 00:26:22 foo ip: [ID 976445 kern.notice] ip_option_process: bad opt 0x5

I think there was no patch for sysctl.[13].

Also: should tcp(4) mention this?


  - Hubert