Accessing repetier-server through ngrok

leumasino

Hi,

I'm trying to connect to a local (of course) repetier-server through a tcp tunnel. In using a standard remote ssh tunnel I get connection to server. Instead, when I try to use ngrok tcp tunnel it doesn't work fine. I've already tested using ngrok tcp tunnel to even encapsulate ssh traffic so it doesn't seem a problem of ngrok mangling the stream.

Let me explain:

I am able to connect to 127.0.0.1:3344 through both tunnels. When connected by ngrok tcp tunnel, I get web main page, images and so but a banner pops up with message "Connection lost" continiuosly.

When connected by ssh tunnel, the very first attempt to open websocket connection pops up the same banner but it is displayed once. Less a second later connection seems to be recovered and all is working.

I analyzed traffic and found out error happens as requesting the websocket.

Here, headers from request through a regular ssh tunnel:

GET /socket/?lang=en&sess=!%23A%5EehC9QOAiiv%25l!UD%23!goHFwvBeGgo HTTP/1.1

Host: mytesthost.com:11000

Connection: Upgrade

Pragma: no-cache

Cache-Control: no-cache

Upgrade: websocket

Origin: http://mytesthost.com:11000

Sec-WebSocket-Version: 13

User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/50.0.2661.102 Safari/537.36

Accept-Encoding: gzip, deflate, sdch

Accept-Language: es-ES,es;q=0.8,en;q=0.6

Cookie: _ga=GA1.2.155945040.1462660236

Sec-WebSocket-Key: qWL9Lc7wi+lCrNm5mIeIkA==

Sec-WebSocket-Extensions: permessage-deflate; client_max_window_bits

An here, from a ngrok tunnel.

GET /socket/?lang=en HTTP/1.1

Host: 0.tcp.ngrok.io:13459

Connection: Upgrade

Pragma: no-cache

Cache-Control: no-cache

Upgrade: websocket

Origin: http://0.tcp.ngrok.io:13459

Sec-WebSocket-Version: 13

User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/50.0.2661.102 Safari/537.36

Accept-Encoding: gzip, deflate, sdch

Accept-Language: es-ES,es;q=0.8,en;q=0.6

Sec-WebSocket-Key: Xxg6EQg1QLlhma1WiA6lOw==

Sec-WebSocket-Extensions: permessage-deflate; client_max_window_bits

As you can see, the main difference is the missing param "sess=" at ngrok request. I guess request for websocker is built by JS code at 127.0.0.1:3344.

Is there some known issue at this? Why does a standard tcp tunnel work but the same tcp tunnul by ngrok fail? Maybe some with response delay?

I'd thank any help or cue you could offer me.

Best regards.

Repetier

It's not sess. In fact websockets create session. If you provide a session you had a connection remembered and you are trying to reconnect with same credentials.

Websocket is started from javascript, but I have the feeling the ther server poco library may have short timeouts during connection. Especially on slower connections I see it more often timeout before going stable. I think I will check the library code for a timeout.

Does ngrok also show/hide timeout ordoes it stay open?

BTW: Looks like a interesting service, will try it soon and see if it works for me or if there is something I can do to get it working.