Intermittent xfreerdp hang only through VPN

Younes Manton younes.m at
Tue Sep 1 22:46:52 PDT 2015

On Tue, Sep 1, 2015 at 7:00 PM, Stuart Henderson <stu at> wrote:
> On 2015/09/01 16:04, Younes Manton wrote:
>> Hi,
>> I've had this problem for at least a couple of years. Whenever I
>> connect to a Windows machine via xfreerdp over my work place VPN the
>> xfreerdp client inevitably hangs. Occassionally SSH sessions will also
>> hang, but this happens much less often. I never see either problem
>> when not connected over VPN.
>> I normally run OpenConnect via Network Manager, but I recently ran it
>> on the command line with -v to watch the output. As best as I can tell
>> the hangs always follow a CSTP rekey and the only thing that's
>> different from the usual is that these lines begin to appear:
>> Send CSTP Keepalive
>> Send CSTP DPD
>> Got CSTP DPD response
>> They seem to stop being emitted once I kill the unresponsive xfreerdp client.
>> On the Windows side I see the following in the Event Viewer every time
>> xfreerdp hangs:
>> The Terminal Server security layer detected an error in the protocol
>> stream and has disconnected the client. Client IP: <my IP>.
>> Anything I can do to debug this?
> Try reducing the mtu requested (openconnect's -m flag).

Thanks. Seems like the server doesn't allow anything outside of
1280-1300, the values I pass to -m are clamped to that range. Neither
helps my problem.

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