From: Stephen Clark <sclark46@earthlink.net>
To: Chris Friesen <chris.friesen@genband.com>
Cc: "Pascal Hambourg" <pascal@plouf.fr.eu.org>,
"Rémi Denis-Courmont" <remi@remlab.net>,
"Linux Kernel Network Developers" <netdev@vger.kernel.org>
Subject: Re: Linux vs FreeBSD Which is correct.
Date: Fri, 19 Aug 2011 15:10:14 -0400 [thread overview]
Message-ID: <4E4EB516.40102@earthlink.net> (raw)
In-Reply-To: <4E4E8CEE.102@genband.com>
On 08/19/2011 12:18 PM, Chris Friesen wrote:
> On 08/18/2011 06:42 AM, Stephen Clark wrote:
>
>> I guess I don't really understand what reverse path filter stuff is all
>> about, much less making it weaker.
>> But using 2 made the pings responses be seen.
>
> It's described in RFC3704. The idea is to block spoofed packets.
>
> From Documentation/networking/ip-sysctl.txt:
>
> rp_filter - INTEGER
> 0 - No source validation.
> 1 - Strict mode as defined in RFC3704 Strict Reverse Path
> Each incoming packet is tested against the FIB and if the interface
> is not the best reverse path the packet check will fail.
> By default failed packets are discarded.
> 2 - Loose mode as defined in RFC3704 Loose Reverse Path
> Each incoming packet's source address is also tested against the FIB
> and if the source address is not reachable via any interface
> the packet check will fail.
>
> Current recommended practice in RFC3704 is to enable strict mode
> to prevent IP spoofing from DDos attacks. If using asymmetric routing
> or other complicated routing, then loose mode is recommended.
>
> The max value from conf/{all,interface}/rp_filter is used
> when doing source validation on the {interface}.
>
> Default value is 0. Note that some distributions enable it
> in startup scripts.
>
>
>
Thanks for taking the time to explain this. Much appreciated.
--
"They that give up essential liberty to obtain temporary safety,
deserve neither liberty nor safety." (Ben Franklin)
"The course of history shows that as a government grows, liberty
decreases." (Thomas Jefferson)
prev parent reply other threads:[~2011-08-19 19:10 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-17 17:03 Linux vs FreeBSD Which is correct Stephen Clark
2011-08-17 17:10 ` Emil S Tantilov
2011-08-17 17:20 ` Stephen Clark
2011-08-17 17:17 ` Rémi Denis-Courmont
2011-08-17 19:44 ` Stephen Clark
2011-08-17 20:15 ` Pascal Hambourg
2011-08-18 12:42 ` Stephen Clark
2011-08-19 16:18 ` Chris Friesen
2011-08-19 19:10 ` Stephen Clark [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4E4EB516.40102@earthlink.net \
--to=sclark46@earthlink.net \
--cc=chris.friesen@genband.com \
--cc=netdev@vger.kernel.org \
--cc=pascal@plouf.fr.eu.org \
--cc=remi@remlab.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).