SSH -L connection successful but localhost port forwarding not working channel 3 open failed connect failed Connection refused

Question

My lab runs RStudio on a server   A couple weeks ago  from my cousin s house  I successfully ssh d into the server and pulled up the server-side RStudio through my local Firefox browser   Now when I try to access the server RStudio from home  via my own router   it doesn t work   I need help troubleshooting  and I m guessing it s some problem on the router   I m running Mac OSX 10 6 8   No idea what the university server s running  but I don t think it s a server-side problem   Here s how it worked the first time I did it  at my cousin s house  first  I VPN into the university network  then I call SSH with port forwarding  then I open a Firefox browser  connect to my localhost port  and it opens up RStudio on the server side which I can access through my local browser window   Here s the problem I m having right now when I try to log-in from my home network   I can make the VPN connection successfully   I can also set up SSH successfully with this command  ssh -v -L 8783 localhost 8783 myacct server com  Here are the last several lines of the verbose output from the successful ssh command   debug1  Authentication succeeded  password   debug1  Local connections to LOCALHOST 8783 forwarded to remote address localhost 8783 debug1  Local forwarding listening on 127 0 0 1 port 8783  debug1  channel 0  new  port listener  debug1  Local forwarding listening on   1 port 8783  debug1  channel 1  new  port listener  debug1  channel 2  new  client-session  debug1  Entering interactive session  Last login  Mon Sep  2 04 02 40 2013 from vpnipaddress   So I think I m still succeeding at the VPN and SSH stage  though I don t know why it says my last login was Sep 2 when I ve logged in a few times since then    Next  I open Firefox  and I type localhost 8783  and instead of getting an RStudio server app through my browser window  I get the following errors   In the Firefox browser window  it says  Server not found  Firefox can t find the server at www localhost com  Check the address for typing errors etc   In the terminal window  it says   debug1  Connection to port 8783 forwarding to localhost port 8783 requested  debug1  channel 3  new  direct-tcpip  channel 3  open failed  connect failed  Connection refused debug1  channel 3  free  direct-tcpip  listening port 8783 for localhost port 8783  connect from 127 0 0 1 port 50420  nchannels 4   I m not sure what I ve got wrong   I haven t changed anything on my laptop since my last successful connection   I m on my own router  instead of my cousin s   so maybe I need to mess with the firewall   I already allowed ports 22 and 8783 to come through the firewall to my laptop  I m not even sure I needed to do that though    Help

User · Answer

Note  localhost is the hostname for an address using the local  loopback  network interface  and 127 0 0 1 is its IP in the IPv4 network standard  it s   1 in IPv6   0 0 0 0 is the IPv4 standard  current network  IP address   I experienced this error with a Docker setup  I had a Docker container running on an external server  and I d  correctly  mapped its ports out as 127 0 0 1 9232 9232  By port-forwarding ssh remote -L 9232 127 0 0 1 9232  I d expected to be able to communicate with the remote server s port 9232 as if it were my own local port   It turned out that the Docker container was internally running its process on 127 0 0 1 9232 rather than 0 0 0 0 9232  and so even though I d specified the container s port-mappings correctly  they weren t on the correct interface for being mapped out

User · Answer

This means the remote vm is not listening to current port i solved this by adding the port in the vm server

User · Answer

ssh -v -L 8783 localhost 8783 myacct server com     channel 3  open failed  connect failed  Connection refused   When you connect to port 8783 on your local system  that connection is tunneled through your ssh link to the ssh server on server com  From there  the ssh server makes TCP connection to localhost port 8783 and relays data between the tunneled connection and the connection to target of the tunnel   The  connection refused  error is coming from the ssh server on server com when it tries to make the TCP connection to the target of the tunnel   Connection refused  means that a connection attempt was rejected  The simplest explanation for the rejection is that  on server com  there s nothing listening for connections on localhost port 8783  In other words  the server software that you were trying to tunnel to isn t running  or else it is running but it s not listening on that port

User · Answer

I used to meet the similar problem because  localhost  was not available on server when it restarted network service  e g   ifdown -a  but followed by only  ifup -eo1   Besides server is not listening to the port  you can also check  localhost  is available or not    ps  Post it just hope someone who has the similar problem may benefit

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I had this problem when I wanted to make a vnc connection via a tunnel  But the vncserver was not running  I solved it by opening the channel on the remote machine with vncserver  3

User · Answer

Posting this to help someone   Symptom   channel 2  open failed  connect failed  Connection refused debug1  channel 2  free  direct-tcpip     listening port 8890 for 169 254 76 1 port 8890     connect from   1 port 52337 to   1 port 8890  nchannels 8   My scenario  i had to use the remote server as a bastion host to connect elsewhere  Final Destination Target  169 254 76 1  port 8890  Through intermediary server with public ip  ec2-54-162-180-7 compute-1 amazonaws com  SSH local port forwarding command   ssh -i   keys dev tst -vnNT -L  8890 169 254 76 1 8890 glue ec2-54-162-180-7 compute-1 amazonaws com   What the problem was  There was no service bound on port 8890 in the target host  i had forgotten to start the service   How did i trouble shoot   SSH into bastion host and then do curl   Hope this helps

User · Answer

Just replace localhost with 127 0 0 1   The answer is based on answers of other people on this page

[macos] SSH -L connection successful, but localhost port forwarding not working "channel 3: open failed: connect failed: Connection refused"

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