Date: Sun, 24 Mar 2024 15:04:15 +0000 From: "Tom Forbes" <tom@tomforb.es> To: "Cy Schubert" <Cy.Schubert@cschubert.com>, freebsd-hackers@freebsd.org Subject: Re: Removing or changing the ping interval restriction for non-root users Message-ID: <4f8b035c-b2cc-4606-a691-f1d86827282b@app.fastmail.com> In-Reply-To: <2D5DD001-DD98-4A8E-9458-6754E6D977EE@cschubert.com> References: <954e1d80-d44f-4c3d-88a7-122dc0f25de4@app.fastmail.com> <2D5DD001-DD98-4A8E-9458-6754E6D977EE@cschubert.com>
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[-- Attachment #1 --] I've personally never come across this limitation on any system that I've used, however it is a good point that there are bound to be systems that have the same limitation. After digging a bit more into the history the limitation was added in this commit[1] in 1998 with the explicit intention to "secure options from user-level D.O.S attacks". A lot of things have changed since 1998, and setting an arbitrary high limit to prevent "ping" and "ping6" from being used to DOS networked devices would be a pretty suspect decision if it was suggested today. I expect a few other distributions have inherited this limit from the original contribution, but to me that doesn't lend a strong argument to keeping it if the underlying reason it exists doesn't make sense anymore _and_ if removing/reducing it is a backwards-compatible, simple and non-invasive change. Tom 1. https://github.com/freebsd/freebsd-src/commit/526f06b278d9252add168aa18b60242c08771165 On Sun, 24 Mar 2024, at 2:48 PM, Cy Schubert wrote: > On March 24, 2024 5:57:01 AM PDT, Tom Forbes <tom@tomforb.es> wrote: > >Hello, > >I maintain a small project called gping[1] that recently added support for FreeBSD. One of the issues I ran into with running this on FreeBSD was that the `ping` command seems to disallow intervals of less than 1 second if you are not running as root[2]. This check was last touched 23 years ago and I'm curious as to why this restriction exists? I assume it's from an earlier time in the internets history, and perhaps is related to potential misuse of the command to flood targets with packets via ping? > > > >If it is then I'd like to suggest that this limitation be removed or is reduced to `0.1` seconds instead? Using `ping` for this kind of thing isn't a viable attack today, and the 1 second limitation seems like it would get in the way of useful uses of the ping command. > > > >Also this is my first post to any *BSD mailing list, so please let me know if this is not the right place to ask this question or propose this! > > > >Thanks, > >Tom > > > >1. https://github.com/orf/gping > >2. https://github.com/freebsd/freebsd-src/blame/8a56ef8d75b42ee7228247466c8c1712de6e3b6f/sbin/ping/ping6.c#L441 > Other UNIX-like systems have the same restriction. At $JOB we use Solaris and various Linux systems. All maintain the same restriction. Other BSDs are the same.I don't think FreeBSD should be an outlier. > > Maybe setgid bit or a capability to remove the restriction may be a better solution. But to reduce the timeout to essentially remove it is IMO unwise. > > -- > Cheers, > Cy Schubert <Cy.Schubert@cschubert.com> > FreeBSD UNIX: <cy@FreeBSD.org> Web: https://FreeBSD.org > NTP: <cy@nwtime.org> Web: https://nwtime.org > e^(i*pi)+1=0 > > Pardon the typos. Small keyboard in use. > [-- Attachment #2 --] <!DOCTYPE html><html><head><title></title><style type="text/css">p.MsoNormal,p.MsoNoSpacing{margin:0}</style></head><body><div>I've personally never come across this limitation on any system that I've used, however it is a good point that there are bound to be systems that have the same limitation. After digging a bit more into the history the limitation was added in this commit[1] in 1998 with the explicit intention to "secure options from user-level D.O.S attacks".<br></div><div><br></div><div>A lot of things have changed since 1998, and setting an arbitrary high limit to prevent "ping" and "ping6" from being used to DOS networked devices would be a pretty suspect decision if it was suggested today. I expect a few other distributions have inherited this limit from the original contribution, but to me that doesn't lend a strong argument to keeping it if the underlying reason it exists doesn't make sense anymore _and_ if removing/reducing it is a backwards-compatible, simple and non-invasive change.<br></div><div><br></div><div>Tom<br></div><ol><li><a href="https://github.com/freebsd/freebsd-src/commit/526f06b278d9252add168aa18b60242c08771165">https://github.com/freebsd/freebsd-src/commit/526f06b278d9252add168aa18b60242c08771165</a><br></li></ol><div><br></div><div>On Sun, 24 Mar 2024, at 2:48 PM, Cy Schubert wrote:<br></div><blockquote type="cite" id="qt" style=""><div>On March 24, 2024 5:57:01 AM PDT, Tom Forbes <<a href="mailto:tom@tomforb.es">tom@tomforb.es</a>> wrote:<br></div><div>>Hello,<br></div><div>>I maintain a small project called gping[1] that recently added support for FreeBSD. One of the issues I ran into with running this on FreeBSD was that the `ping` command seems to disallow intervals of less than 1 second if you are not running as root[2]. This check was last touched 23 years ago and I'm curious as to why this restriction exists? I assume it's from an earlier time in the internets history, and perhaps is related to potential misuse of the command to flood targets with packets via ping?<br></div><div>><br></div><div>>If it is then I'd like to suggest that this limitation be removed or is reduced to `0.1` seconds instead? Using `ping` for this kind of thing isn't a viable attack today, and the 1 second limitation seems like it would get in the way of useful uses of the ping command.<br></div><div>><br></div><div>>Also this is my first post to any *BSD mailing list, so please let me know if this is not the right place to ask this question or propose this!<br></div><div>><br></div><div>>Thanks,<br></div><div>>Tom<br></div><div>><br></div><div>>1. <a href="https://github.com/orf/gping">https://github.com/orf/gping</a><br></div><div>>2. <a href="https://github.com/freebsd/freebsd-src/blame/8a56ef8d75b42ee7228247466c8c1712de6e3b6f/sbin/ping/ping6.c#L441">https://github.com/freebsd/freebsd-src/blame/8a56ef8d75b42ee7228247466c8c1712de6e3b6f/sbin/ping/ping6.c#L441</a><br></div><div>Other UNIX-like systems have the same restriction. At $JOB we use Solaris and various Linux systems. All maintain the same restriction. Other BSDs are the same.I don't think FreeBSD should be an outlier.<br></div><div><br></div><div>Maybe setgid bit or a capability to remove the restriction may be a better solution. But to reduce the timeout to essentially remove it is IMO unwise. <br></div><div><br></div><div>-- <br></div><div>Cheers,<br></div><div>Cy Schubert <<a href="mailto:Cy.Schubert@cschubert.com">Cy.Schubert@cschubert.com</a>><br></div><div>FreeBSD UNIX: <<a href="mailto:cy@FreeBSD.org">cy@FreeBSD.org</a>> Web: <a href="https://FreeBSD.org">https://FreeBSD.org</a><br></div><div>NTP: <<a href="mailto:cy@nwtime.org">cy@nwtime.org</a>> Web: <a href="https://nwtime.org">https://nwtime.org</a><br></div><div> e^(i*pi)+1=0<br></div><div><br></div><div>Pardon the typos. Small keyboard in use.<br></div><div><br></div></blockquote><div><br></div></body></html>
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