Date: Sat, 13 Aug 2011 10:28:13 +0000 From: "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net> To: Kevin Oberman <kob6558@gmail.com> Cc: freebsd-net@freebsd.org, chip@2bithacker.net Subject: Re: Odd TCP RFC1323 Behavior Message-ID: <0C8F244C-CB37-4039-97D2-42C08B3BEA76@lists.zabbadoz.net> In-Reply-To: <CAN6yY1s9nG5Q9AeVQiXm8mRgr3FELTPDTq9CVkWjpTxHx1Q-Eg@mail.gmail.com> References: <20110812214309.GI72508@2bithacker.net> <CAN6yY1s9nG5Q9AeVQiXm8mRgr3FELTPDTq9CVkWjpTxHx1Q-Eg@mail.gmail.com>
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On Aug 12, 2011, at 11:36 PM, Kevin Oberman wrote: > On Fri, Aug 12, 2011 at 2:43 PM, Chip Marshall <chip@2bithacker.net> = wrote: >> I've been digging into an issue with SSH throughput and >> discovered that one of the servers involved isn't using RFC1323 >> window scaling and timestamps. >>=20 >> The server is running 7.3-RELEASE-p3, and has >> net.inet.tcp.rfc1323 set to 1. >>=20 >> When connecting out from the server, it sets both Window Scale >> and TimeStamp options in the SYN packet and everything is fine. >>=20 >> When a connection comes into the server with WS and TS set in >> the SYN, the response varies. For port 53 (named) the SYN/ACK >> has WS/TS options. For port 22 (sshd) the SYN/ACK does not have >> WS/TS options, unless the connection is via lo0. >>=20 >> ssh is OpenSSH_5.2p1, compiled from ports with default options. >>=20 >> I'm really at a loss to explain this. >>=20 >> Why does named use RFC1323 on bce0 when sshd doesn't? >> Why does sshd use RFC1323 on lo0 but not on bce0? >>=20 >> I can provide PCAPs of the SYN, SYN/ACK exchanges if that >> will help. >=20 > Try installing security/openssh-portable from ports and enable the HPN = patches. and let me point out that the relevant patch is in stock HEAD and will = ship by default with 9.0. >=20 > As it stands today, openssh locks the window size to a tiny value. > This causes performance over wide area links to be simply terrible. >=20 > Take a look at http://fasterdata.es.net/fasterdata/say-no-to-scp/ for > more information on the issue. As you will see there, window scaling > is the least of the performance issues with openssh. > --=20 > R. Kevin Oberman, Network Engineer - Retired > E-mail: kob6558@gmail.com > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" --=20 Bjoern A. Zeeb You have to have visions! Stop bit received. Insert coin for new address family.
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