linux-kernel - Re: [PATCH v2] tcp: Add listening address to SYN flood message

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Date:   Fri, 11 Nov 2022 16:10:26 -0800
From:   Eric Dumazet <edumazet@...gle.com>
To:     Jamie Bainbridge <jamie.bainbridge@...il.com>
Cc:     Stephen Hemminger <stephen@...workplumber.org>,
        "David S. Miller" <davem@...emloft.net>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        David Ahern <dsahern@...nel.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] tcp: Add listening address to SYN flood message

On Fri, Nov 11, 2022 at 4:00 PM Jamie Bainbridge
<jamie.bainbridge@...il.com> wrote:
>
> On Sat, 12 Nov 2022 at 04:20, Stephen Hemminger
> <stephen@...workplumber.org> wrote:
> >
> > On Fri, 11 Nov 2022 14:59:32 +1100
> > Jamie Bainbridge <jamie.bainbridge@...il.com> wrote:
> >
> > > +         xchg(&queue->synflood_warned, 1) == 0) {
> > > +             if (IS_ENABLED(CONFIG_IPV6) && sk->sk_family == AF_INET6) {
> > > +                     net_info_ratelimited("%s: Possible SYN flooding on port %pI6c.%u. %s.\n",
> > > +                                     proto, &sk->sk_v6_rcv_saddr,
> > > +                                     sk->sk_num, msg);
> > > +             } else {
> > > +                     net_info_ratelimited("%s: Possible SYN flooding on port %pI4.%u. %s.\n",
> > > +                                     proto, &sk->sk_rcv_saddr,
> > > +                                     sk->sk_num, msg);
> >
> > Minor nit, the standard format for printing addresses would be to use colon seperator before port
> >
> >                 if (IS_ENABLED(CONFIG_IPV6) && sk->sk_family == AF_INET6) {
> >                         net_info_ratelimited("%s: Possible SYN flooding on [%pI6c]:%u. %s.\n",
> >                                         proto, &sk->sk_v6_rcv_saddr, sk->sk_num, msg);
> >                 } else {
> >                         net_info_ratelimited("%s: Possible SYN flooding on %pI4:%u. %s.\n",
> >                                         proto, &sk->sk_rcv_saddr, sk->sk_num, msg);
>
> I considered this too, though Eric suggested "IP.port" to match tcpdump.
>
> Please let me know which advice to follow?

IPv6 [address]:port is also a standard (and unambiguous) way.

https://www.rfc-editor.org/rfc/rfc5952#page-11