Debian 8, OpenSSH Hangs, Backported Kernel on MacBook Pro

[rnldaddy]

Hello,

I have a MacBook Pro running Debian 8.6 with a backported kernel:

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$ uname -a
Linux mbphost 4.8.0-0.bpo.2-amd64 #1 SMP Debian 4.8.11-1~bpo8+1 (2016-12-14) x86_64 GNU/Linux)

which was needed for the proprietary brcmfmac43602-pcie.bin drivers for the

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# lspci | grep 43602
03:00.0 Network controller: Broadcom Limited BCM43602 802.11ac Wireless LAN SoC (rev 01)

When I attempt to ssh to a machine on my local subnet, things work as expected. When I attempt to ssh outside my subnet, OpenSSH hangs. However, if I use PuTTY I connect just fine to all locations. To make matters more confusing, if I use a TP-Link N150 USB Wifi device, both OpenSSH and PuTTY work just fine. Additionally, in MacOS X (Sierra), OpenSSH works just fine too!

One would *think* this leads to the proprietary Broadcom drivers as the culprit. However, at my university, OpenSSH works just fine with the Broadcom in Linux as well!

It seems I have "evidence" Broadcom is the culprit, the WiFi AP may be the culprit, and/or OpenSSH is the culprit. Oh, and by the way, I have several other Debian 8 systems all on the same subnet as the Mac, all successful at SSHing outside the subnet with no issues (i.e. all OpenSSH versions are the same).

I'm so confused. I've captured output of both client and server for both successful and unsuccessful connections and can not find any differences. (Can provide upon request.)

Thoughts?

--RnLDaddy

[rnldaddy]

Update:

While I don't consider this a fix, it's a definite workaround. From this http://askubuntu.com/questions/344863/s ... y-or-so-on forum post, it seems there may be Type of Service (TOS) issue in the IP packet when going through a NAT router. To get around it, use NetCat (nc) to tunnel the traffic (NetCat does not utilize the TOS field apparently) as a proxy:

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$ ssh -o "ProxyCommand nc %h %p" {user-name}@host.tld

Alternatively, and if this worked, add ProxyCommand to your ~/.ssh/config:

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ProxyCommand nc %h %p

I'd still like to know if there is a proper fix, but perhaps this can help others in the meantime.

--RnLDaddy