From nobody Tue Aug 13 15:45:38 2024 X-Original-To: freebsd-hackers@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4WjwjN6NbFz5Sw74 for ; Tue, 13 Aug 2024 15:46:32 +0000 (UTC) (envelope-from ararslan@comcast.net) Received: from resqmta-a2p-658917.sys.comcast.net (resqmta-a2p-658917.sys.comcast.net [IPv6:2001:558:fd01:2bb4::3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4WjwjM6GDPz4L3L for ; Tue, 13 Aug 2024 15:46:31 +0000 (UTC) (envelope-from ararslan@comcast.net) Authentication-Results: mx1.freebsd.org; dkim=pass header.d=comcast.net header.s=20190202a header.b=iOVC9UqS; dmarc=pass (policy=quarantine) header.from=comcast.net; spf=pass (mx1.freebsd.org: domain of ararslan@comcast.net designates 2001:558:fd01:2bb4::3 as permitted sender) smtp.mailfrom=ararslan@comcast.net Received: from resomta-a2p-646770.sys.comcast.net ([96.103.145.230]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 256/256 bits) (Client did not present a certificate) by resqmta-a2p-658917.sys.comcast.net with ESMTPS id dp0GsgfePxMjhdtiuspFAB; Tue, 13 Aug 2024 15:46:12 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=20190202a; t=1723563972; bh=Ogc+ojgSnK10lHRbVpeQp10EWQQwR2n9fwj+oSa0oBM=; h=Received:Received:From:Message-Id:Content-Type:Mime-Version: Subject:Date:To:Xfinity-Spam-Result; b=iOVC9UqSEs85FDBWR0IGYXQ2AUbAfwpby4LuH+ylat7CEAAlkA27+A2ohifre+5w7 xKs46f39ugZNCSi1sqOP8xjdcsQRXWhmNLfgFZfCT21YMH3utP1ExxEbkjfVViCv97 ind7bj2ySKpdkV56F9YGyqVhv/b536SD+a/rSntbDlAmJfqxb5t3Cyi2Z0HVMBFIBJ tdIn8by0PKhMPlVtg3dhCaOw/v2hoUwg7E3bHqi9roA/4gVgUsMN6HPrreZNBpZIGK gNq+hXG/P8x2MIVOoAhcIoj6jqRauAlyfPQsQB9eao9zrE0xtbRi2ho+jdWE/pBKuV Rons40jeQjAkQ== Received: from smtpclient.apple ([67.160.29.205]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 256/256 bits) (Client did not present a certificate) by resomta-a2p-646770.sys.comcast.net with ESMTPSA id dtiWswuCDvtH6dtiXs8izf; Tue, 13 Aug 2024 15:45:50 +0000 From: Alex Arslan Message-Id: <607068B0-E531-4D7F-8B61-923EE5DC443D@comcast.net> Content-Type: multipart/alternative; boundary="Apple-Mail=_B98B5773-0FFF-4FD1-B07B-89818E4619B7" List-Id: Technical discussions relating to FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-hackers List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-hackers@FreeBSD.org Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3774.600.62\)) Subject: Re: Diagnosing virtual machine network issues Date: Tue, 13 Aug 2024 08:45:38 -0700 In-Reply-To: <202408101611.47AGBMV4065737@gndrsh.dnsmgr.net> Cc: Bakul Shah , FreeBSD Hackers To: "Rodney W. Grimes" References: <202408101611.47AGBMV4065737@gndrsh.dnsmgr.net> X-Mailer: Apple Mail (2.3774.600.62) X-CMAE-Envelope: MS4xfBww4skvlra7rs9vmF0uoj2bkQWwGiS2SUqMVgl9oazCy3ZkIEyg4Frcx7585JvrEj4EjCzTyYQ/e0W3aUZ0j/NhGLRnXILzXtipZKzqvENVZHuBIlag /sYrMeCuWNKJM0a6R3a9k331qMBPmLfYIUI3oBvAEUJEd7XK7MDUX3laZzujT1HVIidFFBNuWnS8uI/+VrDYNg7i5jCQzV8CQ9LbriKge1gjoyqDNSButYe/ nclm66s719TGvxZABBskkvNsSod1nk8icYJtELRk37E= X-Spamd-Bar: / X-Spamd-Result: default: False [-0.72 / 15.00]; HFILTER_HELO_5(3.00)[resqmta-a2p-658917.sys.comcast.net]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_MEDIUM(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.72)[-0.720]; DMARC_POLICY_ALLOW(-0.50)[comcast.net,quarantine]; R_SPF_ALLOW(-0.20)[+ip6:2001:558:fd01:2bb4::/64]; R_DKIM_ALLOW(-0.20)[comcast.net:s=20190202a]; MIME_GOOD(-0.10)[multipart/alternative,text/plain]; RCVD_TLS_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; ARC_NA(0.00)[]; TO_DN_ALL(0.00)[]; FREEMAIL_FROM(0.00)[comcast.net]; MIME_TRACE(0.00)[0:+,1:+,2:~]; DKIM_TRACE(0.00)[comcast.net:+]; ASN(0.00)[asn:7922, ipnet:2001:558::/29, country:US]; FREEMAIL_ENVFROM(0.00)[comcast.net]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; RCPT_COUNT_THREE(0.00)[3]; MLMMJ_DEST(0.00)[freebsd-hackers@freebsd.org]; APPLE_MAILER_COMMON(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; DWL_DNSWL_NONE(0.00)[comcast.net:dkim] X-Rspamd-Queue-Id: 4WjwjM6GDPz4L3L --Apple-Mail=_B98B5773-0FFF-4FD1-B07B-89818E4619B7 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 Hi Rodney, > On Aug 10, 2024, at 9:11=E2=80=AFAM, Rodney W. Grimes = wrote: >=20 >>=20 >>=20 >>> On Aug 2, 2024, at 5:58?PM, Bakul Shah wrote: >>>=20 >>> On Aug 2, 2024, at 3:52?PM, Alex Arslan = wrote: >>>>=20 >>>>> Just a comment and a name server line: >>>>>=20 >>>>> $ cat /etc/resolv.conf >>>>> # Generated by resolvconf >>>>> nameserver 192.168.122.1 >>>>=20 >>>> I believe that is the host IP, so I guess the VM is using the host = for DNS >>>> resolution? Interestingly, if I add `nameserver 8.8.8.8` below the = line >>>> with the host IP, it takes 10 seconds rather than 30 to reach the = expected >>>> domain resolution failure. If I put 8.8.8.8 above the host IP, the = domain >>>> resolution failure is instantaneous. >>>=20 >>> What does your host use as a namesever? >>=20 >> The nameserver is 127.0.0.53. It sets options edns0 and trust-ad, and >> includes a search entry as well. >=20 > First, is that a typo and you mean 127.0.0.1:53? No, the host's /etc/resolv.conf has `nameserver 127.0.0.53`, I just went back and rechecked to be sure. > Second, is that name server locked to 127.0.0.1, or is it > actually listinging on *:53? If it is LOCKED you have no name server > running on 192.168.122.1 to be reached by the VM, if it is NOT locked > can the guest ping 192.168.122.1, and can it reach dns at that IP on > port 53? Can the host send a packet BACK to the guest? I apologize but I don't really know enough about these things to know = how to answer your question. I did post the output of tcpdump on the VM and the host a while back but that was for the invalid request, so that probably doesn't capture what you're describing. > Third you can "fix" the "nameserver 192.168.122.1" entry in = /etc/resolv.conf > by configuring the DHCP server that handed out the lease to the VM to = send > a namserver entry of 8.8.8.8. If I understand correctly, that is indeed what we've done as a Band-Aid = fix for the time being: I added the line `prepend_nameservers=3D8.8.8.8` to /etc/resolvconf.conf. >>=20 >>>=20 >>>> Not a particularly satisfying conclusion to this saga as I don't = understand >>>> why it's happening but at least I have a workaround that should = hopefully >>>> do the job. I really appreciate everyone's help and input thus far! >>>>=20 >>>> What's the best way to add `nameserver 8.8.8.8` to /etc/resolv.conf = as >>>> part of the VM's configuration? >>>=20 >>> You should diagnose the problem of the nameserver at 192.168.122.1 >>> and fix it to act properly. I don't use vm (just bhyve) so can't = help >>> you with its config. >>=20 >> I do still plan to try to figure out what the actual issue is, but I = also >> now have a path forward in the meantime. :) >>=20 >>=20 >=20 > --=20 > Rod Grimes = rgrimes@freebsd.org --Apple-Mail=_B98B5773-0FFF-4FD1-B07B-89818E4619B7 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8
Hi Rodney,

On Aug 10, 2024, at 9:11=E2=80=AFAM, Rodney W. Grimes = <freebsd-rwg@gndrsh.dnsmgr.net> wrote:



On Aug 2, = 2024, at 5:58?PM, Bakul Shah <bakul@iitbombay.org> = wrote:

On Aug 2, 2024, at 3:52?PM, Alex Arslan = <ararslan@comcast.net> wrote:

Just a comment and a name = server line:

$ cat /etc/resolv.conf
# Generated by = resolvconf
nameserver 192.168.122.1

I believe = that is the host IP, so I guess the VM is using the host for = DNS
resolution? Interestingly, if I add `nameserver 8.8.8.8` below = the line
with the host IP, it takes 10 seconds rather than 30 to = reach the expected
domain resolution failure. If I put 8.8.8.8 above = the host IP, the domain
resolution failure is = instantaneous.

What does your host use as a = namesever?

The nameserver is 127.0.0.53. It sets = options edns0 and trust-ad, and
includes a search entry as = well.

First, = is that a typo and you mean 127.0.0.1:53?

No, = the host's /etc/resolv.conf has `nameserver 127.0.0.53`, I just = went
back and rechecked to be sure.

Second, = is that name server locked to 127.0.0.1, or is it
actually listinging on *:53?  If it is = LOCKED you have no name server
running = on 192.168.122.1 to be reached by the VM, if it is NOT locked
can the guest ping 192.168.122.1, and can = it reach dns at that IP on
port = 53?   Can the host send a packet BACK to the guest?

I apologize but I = don't really know enough about these things to know how
to = answer your question. I did post the output of tcpdump on the VM = and
the host a while back but that was for the invalid = request, so that
probably doesn't capture what you're = describing.

Third you can "fix" the "nameserver = 192.168.122.1" entry in /etc/resolv.conf
by = configuring the DHCP server that handed out the lease to the VM to = send
a namserver entry of = 8.8.8.8.

If I understand correctly, = that is indeed what we've done as a Band-Aid fix
for the time = being: I added the line `prepend_nameservers=3D8.8.8.8` = to
/etc/resolvconf.conf.



Not a particularly satisfying conclusion to this saga as I = don't understand
why it's happening but at least I have a workaround = that should hopefully
do the job. I really appreciate everyone's help = and input thus far!

What's the best way to add `nameserver = 8.8.8.8` to /etc/resolv.conf as
part of the VM's = configuration?

You should diagnose the problem of = the nameserver at 192.168.122.1
and fix it to act properly. I don't = use vm (just bhyve) so can't help
you with its = config.

I do still plan to try to figure out what = the actual issue is, but I also
now have a path forward in the = meantime. :)



-- 
Rod Grimes =             &n= bsp;           &nbs= p;            =            <= a href=3D"mailto:rgrimes@freebsd.org" style=3D"font-family: Helvetica; = font-size: 12px; font-style: normal; font-variant-caps: normal; = font-weight: 400; letter-spacing: normal; orphans: auto; text-align: = start; text-indent: 0px; text-transform: none; white-space: normal; = widows: auto; word-spacing: 0px; -webkit-text-stroke-width: = 0px;">rgrimes@freebsd.org

= --Apple-Mail=_B98B5773-0FFF-4FD1-B07B-89818E4619B7--