From: Stuart Henderson <stu@spacehopper.org>
Subject: Re: ntpd - use dscp (diff)
To: David Hill <dhill@mindcry.org>
Cc: tech@openbsd.org
Date: Tue, 21 Oct 2025 22:09:37 +0100

might be an idea to see how things settle with the EF changes in ssh
first before changing others - the next week or two following 7.8
release should see that in the hands of more users

re: https://marc.info/?l=openssh-unix-dev&m=176038595912667&w=2


On 2025/10/21 20:44, David Hill wrote:
> Hello,
> 
> This diff adds DSCP EF for ipv6 ntp packets, and switches ipv4 to it as
> well.  This also matches https://github.com/ntp-project/ntp/blob/8a37f9b66d374b164531f0189caba4cbfd68bb61/ntpd/ntp_io.c#L79
> 
> Thoughts?
> 
> Index: usr.sbin/ntpd/client.c
> ===================================================================
> RCS file: /cvs/src/usr.sbin/ntpd/client.c,v
> diff -u -p -r1.118 client.c
> --- usr.sbin/ntpd/client.c	20 Dec 2023 15:36:36 -0000	1.118
> +++ usr.sbin/ntpd/client.c	21 Oct 2025 20:09:55 -0000
> @@ -181,10 +181,17 @@ client_query(struct ntp_peer *p)
>  			} else
>  				fatal("client_query connect");
>  		}
> -		val = IPTOS_LOWDELAY;
> -		if (p->addr->ss.ss_family == AF_INET && setsockopt(p->query.fd,
> -		    IPPROTO_IP, IP_TOS, &val, sizeof(val)) == -1)
> -			log_warn("setsockopt IPTOS_LOWDELAY");
> +		val = IPTOS_DSCP_EF;
> +		switch (p->addr->ss.ss_family) {
> +		case AF_INET:
> +			if (setsockopt(p->query.fd, IPPROTO_IP, IP_TOS,
> +			    &val, sizeof(val)) == -1)
> +				log_warn("setsockopt IPTOS_DSCP_EF");
> +		case AF_INET6:
> +			if (setsockopt(p->query.fd, IPPROTO_IPV6, IPV6_TCLASS,
> +			    &val, sizeof(val)) == -1)
> +				log_warn("setsockopt IPTOS_DSCP_EF");
> +		}
>  		val = 1;
>  		if (setsockopt(p->query.fd, SOL_SOCKET, SO_TIMESTAMP,
>  		    &val, sizeof(val)) == -1)
> Index: usr.sbin/ntpd/server.c
> ===================================================================
> RCS file: /cvs/src/usr.sbin/ntpd/server.c,v
> diff -u -p -r1.44 server.c
> --- usr.sbin/ntpd/server.c	3 Sep 2016 11:52:06 -0000	1.44
> +++ usr.sbin/ntpd/server.c	21 Oct 2025 20:09:55 -0000
> @@ -39,7 +39,7 @@ setup_listeners(struct servent *se, stru
>  	u_int8_t		*a6;
>  	size_t			 sa6len = sizeof(struct in6_addr);
>  	u_int			 new_cnt = 0;
> -	int			 tos = IPTOS_LOWDELAY, rdomain = 0;
> +	int			 tos = IPTOS_DSCP_EF, rdomain = 0;
> 
>  	TAILQ_FOREACH(lap, &lconf->listen_addrs, entry) {
>  		switch (lap->sa.ss_family) {
> @@ -119,10 +119,16 @@ setup_listeners(struct servent *se, stru
>  		if ((la->fd = socket(la->sa.ss_family, SOCK_DGRAM, 0)) == -1)
>  			fatal("socket");
> 
> -		if (la->sa.ss_family == AF_INET && setsockopt(la->fd,
> -		    IPPROTO_IP, IP_TOS, &tos, sizeof(tos)) == -1)
> -			log_warn("setsockopt IPTOS_LOWDELAY");
> -
> +		switch (la->sa.ss_family) {
> +		case AF_INET:
> +			if (setsockopt(la->fd, IPPROTO_IP, IP_TOS,
> +			    &tos, sizeof(tos)) == -1)
> +				log_warn("setsockopt IPTOS_DSCP_EF");
> +		case AF_INET6:
> +			if (setsockopt(la->fd, IPPROTO_IPV6, IPV6_TCLASS,
> +			    &tos, sizeof(tos)) == -1)
> +				log_warn("setsockopt IPTOS_DSCP_EF");
> +		}
>  		if (la->rtable != -1 &&
>  		    setsockopt(la->fd, SOL_SOCKET, SO_RTABLE, &la->rtable,
>  		    sizeof(la->rtable)) == -1)
>