From nobody Wed Jun 12 22:37:04 2024 X-Original-To: freebsd-net@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 4W00lr4Ndkz5NbJM for ; Wed, 12 Jun 2024 22:37:12 +0000 (UTC) (envelope-from bsd-lists@bsdforge.com) Received: from udns.ultimatedns.net (udns.ultimatedns.net [24.113.41.81]) (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-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "ultimatedns.net", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4W00lq48xGz4WQy; Wed, 12 Jun 2024 22:37:11 +0000 (UTC) (envelope-from bsd-lists@bsdforge.com) Authentication-Results: mx1.freebsd.org; dkim=pass header.d=ultimatedns.net header.s=mx99 header.b=M1XpBQ8X; spf=none (mx1.freebsd.org: domain of bsd-lists@bsdforge.com has no SPF policy when checking 24.113.41.81) smtp.mailfrom=bsd-lists@bsdforge.com Received: from ultimatedns.net (localhost [127.0.0.1]) by udns.ultimatedns.net (8.16.1/8.16.1) with ESMTP id 45CMb5HQ091289; Wed, 12 Jun 2024 15:37:11 -0700 (PDT) (envelope-from bsd-lists@bsdforge.com) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=ultimatedns.net; s=mx99; t=1718231831; x=1718232431; r=y; bh=fTvLKGEkOXtlLwIG6hno8NI/LdgTkk7oCIHjWJ2oR4s=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=M1XpBQ8XcELhqo2U+j4PwhP4olSgMVyT/J8HcY3jaVcP3m0OuxD4Kg1GlId/4VFkt NhfWuLQD2kHh6nn5gsrg9z/lm3P+q4LmSrnvat/k5NkCe64DmUuYWYoJU0ZZTuQbbQ acsUzuc0XUMSIbn0FDbdJw9XHZ7YQIMjbVwnGzOUOw8y0BHf4suGNbHyPdR1ta0Z+L Ka/K6XdnJ7JV6s+dZQYduRKer4PvQKR7eSGMfL8dIOUjl+pid84YC4fAuN9xtSEtSm IFWHb+QqN0GtxgiZPZsuo+2NNZMzBe7g3LEvAH0u6XTTztaTS5leyE2tKgPB7g2I+C NnS0c1MwkmqKw== List-Id: Networking and TCP/IP with FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-net List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-net@FreeBSD.org MIME-Version: 1.0 Date: Wed, 12 Jun 2024 15:37:04 -0700 From: Chris To: "Rodney W. Grimes" Cc: Ed Maste , freebsd-net@freebsd.org Subject: Re: Discarding inbound ICMP REDIRECT by default In-Reply-To: <72ceb2fe26812a237a17bd8de4024b7f@bsdforge.com> References: <202406122147.45CLlsgN042313@gndrsh.dnsmgr.net> <72ceb2fe26812a237a17bd8de4024b7f@bsdforge.com> User-Agent: UDNSMS/17.0 Message-ID: <7628aa81fb381a08cbb1c2fabf6bc493@bsdforge.com> X-Sender: bsd-lists@bsdforge.com Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit X-Spamd-Bar: / X-Rspamd-Pre-Result: action=no action; module=multimap; Matched map: local_wl_ip X-Spamd-Result: default: False [-0.20 / 15.00]; R_DKIM_ALLOW(-0.20)[ultimatedns.net:s=mx99]; MIME_GOOD(-0.10)[text/plain]; ONCE_RECEIVED(0.10)[]; ASN(0.00)[asn:11404, ipnet:24.113.0.0/16, country:US]; DKIM_TRACE(0.00)[ultimatedns.net:+]; R_SPF_NA(0.00)[no SPF record]; local_wl_ip(0.00)[24.113.41.81]; FROM_EQ_ENVFROM(0.00)[]; MLMMJ_DEST(0.00)[freebsd-net@freebsd.org]; FROM_HAS_DN(0.00)[]; MIME_TRACE(0.00)[0:+] X-Rspamd-Queue-Id: 4W00lq48xGz4WQy On 2024-06-12 15:05, Chris wrote: > On 2024-06-12 14:47, Rodney W. Grimes wrote: >>> I propose that we start dropping inbound ICMP REDIRECTs by default, by >>> setting the net.inet.icmp.drop_redirect sysctl to 1 by default (and >>> changing the associated rc.conf machinery). I've opened a Phabricator >>> review at https://reviews.freebsd.org/D45102. >> >> I propse that we NOT do this. If you need this to protect your end >> node your probably doing something really unsafe network wise. The >> place that ICMP REDIRECTS should be dropped, and is most places, is >> at access routers and firewalls. >> >> Any one that needs this change to protect there network has larger >> issues than an ICMP REDIECT causing some issues. >> >> ICMP redirectr are very usefull for not having to run routing >> protocols on all your end nodes and allowing your edge/access >> routers tell your internal hosts via redirects how to get to >> places more efficiently. >> >>> >>> ICMP REDIRECTs served a useful purpose in earlier networks, but on >> They still serve this very usefull purpose. >> >>> balance are more likely to represent a security issue today than to >>> provide a routing benefit. With the change in review it is of course >>> still possible to enable them if desired for a given installation. >>> This change would appear in FreeBSD 15.0 and would not be MFC'd. >>> >>> One question raised in the review is about switching the default to >>> YES but keeping the special handling for "auto" (dropping ICMP >>> REDIRECT if a routing daemon is in use, honouring them if not). I >>> don't think this is particularly valuable given that auto was >>> introduced to override the default NO when necessary; there's no need >>> for it with the default being YES. That functionality could be >>> maintained if there is a compelling use case, though. >> >> The policy that is there now is exactly how things should be configured >> for a host in a network protected by a proper router w/firewall. >> The existing "auto" does exactly the right thing. >> >>> >>> If you have any questions or feedback please follow up here or in the >>> review. > As Rodeney already effectively explains; dropping packets makes routing, > and discovery exceedingly difficult. Which is NOT what the average user > wants, > or expects. I use "set block-policy drop" in pf(4). But as already noted, > this is for "filtering" purposes. Your suggestion also has the negative > affect > of hanging remote ports. Which can result in other negative results by > peers. > > Please don't. :) >>> >>> > --Chris OK, now having actually read the (phab) review. I'm of the opposite opinion. Your review seems to make the right decision. :) --Chris