Date: Fri, 28 Aug 2015 12:14:25 -0700 From: Chris Stankevitz <chris@stankevitz.com> To: freebsd-net@freebsd.org Subject: Re: ssh over WAN: TCP window too small Message-ID: <55E0B311.9070501@stankevitz.com> In-Reply-To: <55DCF080.7080208@stankevitz.com> References: <55DCF080.7080208@stankevitz.com>
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On 8/25/15 3:47 PM, Chris Stankevitz wrote: > Can anyone explain my abysmally small TCP window? So I believe this is the story: 1. openssh limits the size of some outgoing buffer to 65KB 2. openssh/HPN tries to improve on this by increasing the size of the outgoing buffer to match getsockopt(SO_SNDBUF) 3. When asked for the current SO_SNDBUF, FreeBSD 10.1 reports the high watermark of the outgoing buffer, not its capacity. 4. (2) is essentially a no-op because of (3). 5. openssh/HPN can be tricked into increasing its outgoing buffer by increasing sendspace/recvspace My comments: - (3) is not what I would expect -- perhaps the ssh/HPN folks would agree with me. Shouldn't getsockopt(SO_SNDBUF) return the same value set by setsockopt(SO_SNDBUF)? - I do not understand the mechanism by which (5) works. Chris
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