Date: Sun, 19 Nov 2023 09:15:04 +0800 From: Zhenlei Huang <zlei@FreeBSD.org> To: =?utf-8?Q?Mina_Gali=C4=87?= <freebsd@igalic.co> Cc: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org> Subject: Re: How to tell if a network interface was renamed (and from what) Message-ID: <E5F5F61E-3827-404A-A46F-BBCF45A29A82@FreeBSD.org> In-Reply-To: <pdHC0ObBkAbx2HfFIhWYaB5-dmQDEUzNTWvVVJAuJV7FWdWWeSwybVFD-uyBUxPlqDRpAW7D1aAZsbrTxEj9kqsq7ESgO41srPmS-PcXGqw=@igalic.co> References: <pdHC0ObBkAbx2HfFIhWYaB5-dmQDEUzNTWvVVJAuJV7FWdWWeSwybVFD-uyBUxPlqDRpAW7D1aAZsbrTxEj9kqsq7ESgO41srPmS-PcXGqw=@igalic.co>
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--Apple-Mail=_6FD7852A-BC35-4FE3-97EE-B65056ABE9B5 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 > On Nov 19, 2023, at 6:20 AM, Mina Gali=C4=87 <freebsd@igalic.co> = wrote: >=20 > Hi folks, >=20 > Linux has an "easy" way of telling if an interface has been renamed. > See cloud-init's is_renamed function: = https://github.com/canonical/cloud-init/blob/5496745b394f9b7b9eaf57fd61933= 0d484ce2da8/cloudinit/net/__init__.py#L338-L350 > This code reads /sys/class/net/<netif>/name_assign_type and if that is = 3 or 4, it's been renamed. >=20 > I can't even think of an sensible way of replicating that. > I can only think of terrible / wrong way of finding it out: >=20 > dmesg | grep "changing name to '<new-netif>'" >=20 > a less terrible method would be to check for, say: >=20 > sysctl dev.<new-netif>.0.%driver >=20 > if that fails, we probably have a renamed interface=E2=80=A6 but we = don't know what it was renamed from, and this only works for *real* = interfaces, not for cloned devices, or epairs. >=20 > Now, ignoring my terrible hacky attempts at command line tooling, I = would also happily accept a solution in C, which is fairly easily = accessible from Python, and which we already use to figure out the = uptime (or rather, the boottime): = https://github.com/canonical/cloud-init/blob/5496745b394f9b7b9eaf57fd61933= 0d484ce2da8/cloudinit/util.py#L2073-L2105 >=20 > Looking forward to reading your ideas. FreeBSD currently does not preserve the old ( original ) name of = interfaces if it is renamed ( either physical or cloned ones ). While there's an attempt https://reviews.freebsd.org/D28247 = <https://reviews.freebsd.org/D28247>; to get the device name (physical = ones) but it is not perfect and not completed. So may I ask why you need to know if a network interface was renamed ? >=20 > Kind regards, >=20 > Mina Gali=C4=87 >=20 Best regards, Zhenlei --Apple-Mail=_6FD7852A-BC35-4FE3-97EE-B65056ABE9B5 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 <html><head><meta http-equiv=3D"Content-Type" content=3D"text/html; = charset=3Dutf-8"></head><body style=3D"word-wrap: break-word; = -webkit-nbsp-mode: space; line-break: after-white-space;" class=3D""><br = class=3D""><div><br class=3D""><blockquote type=3D"cite" class=3D""><div = class=3D"">On Nov 19, 2023, at 6:20 AM, Mina Gali=C4=87 <<a = href=3D"mailto:freebsd@igalic.co" class=3D"">freebsd@igalic.co</a>> = wrote:</div><br class=3D"Apple-interchange-newline"><div class=3D""><div = class=3D"">Hi folks,<br class=3D""><br class=3D"">Linux has an "easy" = way of telling if an interface has been renamed.<br class=3D"">See = cloud-init's is_renamed function: <a = href=3D"https://github.com/canonical/cloud-init/blob/5496745b394f9b7b9eaf5= 7fd619330d484ce2da8/cloudinit/net/__init__.py#L338-L350" = class=3D"">https://github.com/canonical/cloud-init/blob/5496745b394f9b7b9e= af57fd619330d484ce2da8/cloudinit/net/__init__.py#L338-L350</a><br = class=3D"">This code reads /sys/class/net/<netif>/name_assign_type = and if that is 3 or 4, it's been renamed.<br class=3D""><br class=3D"">I = can't even think of an sensible way of replicating that.<br class=3D"">I = can only think of terrible / wrong way of finding it out:<br = class=3D""><br class=3D"">dmesg | grep "changing name to = '<new-netif>'"<br class=3D""><br class=3D"">a less terrible method = would be to check for, say:<br class=3D""><br class=3D"">sysctl = dev.<new-netif>.0.%driver<br class=3D""><br class=3D"">if that = fails, we probably have a renamed interface=E2=80=A6 but we don't know = what it was renamed from, and this only works for *real* interfaces, not = for cloned devices, or epairs.<br class=3D""><br class=3D"">Now, = ignoring my terrible hacky attempts at command line tooling, I would = also happily accept a solution in C, which is fairly easily accessible = from Python, and which we already use to figure out the uptime (or = rather, the boottime): <a = href=3D"https://github.com/canonical/cloud-init/blob/5496745b394f9b7b9eaf5= 7fd619330d484ce2da8/cloudinit/util.py#L2073-L2105" = class=3D"">https://github.com/canonical/cloud-init/blob/5496745b394f9b7b9e= af57fd619330d484ce2da8/cloudinit/util.py#L2073-L2105</a><br class=3D""><br= class=3D"">Looking forward to reading your ideas.<br = class=3D""></div></div></blockquote><div><br class=3D""></div><div>FreeBSD= currently does not preserve the old ( original ) name of interfaces if = it is renamed ( either physical or cloned ones ).</div><div>While = there's an attempt <a href=3D"https://reviews.freebsd.org/D28247" = class=3D"">https://reviews.freebsd.org/D28247</a>; to get the = device name (physical ones) but it is not perfect and not = completed.</div><div><br class=3D""></div><div>So may I ask why you need = to know if a network interface was renamed ?</div><br = class=3D""><blockquote type=3D"cite" class=3D""><div class=3D""><div = class=3D""><br class=3D"">Kind regards,<br class=3D""><br class=3D"">Mina = Gali=C4=87<br class=3D""><br class=3D""></div></div></blockquote></div><br= class=3D""><div class=3D""> <div>Best regards,</div><div>Zhenlei</div> </div> <br class=3D""></body></html>= --Apple-Mail=_6FD7852A-BC35-4FE3-97EE-B65056ABE9B5--
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