OpenSSH Hangs After Successful Authentication

[Darren Tucker]

On Mon, Jan 9, 2017 at 8:54 AM, David A. Gershman
<dagershman at dagertech.net> wrote:
> Using my _internal_ WiFi card, OpenSSH succeeds to local (internal) LAN
> hosts, but hangs after authentication to external LAN hosts; however
> PuTTY works for all hosts.

Two possibilities I can think of:

1) MTU black hole.  Check the "send-q" column on both client and
server in netstat when it's in the hung state, compare MTUs between
working and not working interfaces and try "ifconfig wlan0 mtu 576"
before starting the ssh connection.

2) ssh(1) sets the IP type of service bits around the time of your
observed hang.  In the past we have had reports of stateful devices
not coping with the QoS of an established connection changing.  Try
"ssh -o 'IPQos lowdelay lowdelay' yourserver".

My bet is on #1, and my guess is the default MTU is different between
your interfaces.

-- 
Darren Tucker (dtucker at zip.com.au)
GPG key 11EAA6FA / A86E 3E07 5B19 5880 E860  37F4 9357 ECEF 11EA A6FA (new)
    Good judgement comes with experience. Unfortunately, the experience
usually comes from bad judgement.