[Bug 1259939] Re: ssh -g has no effect if master socket already open

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On 2013-12-11T15:36:36+00:00 Imwellcushtymelike wrote:

>From the man page:
 -g      Allows remote hosts to connect to local forwarded ports.

When working with a control socket, this works fine if -g is included
with the initial connect attempt, for example:

$ cat ~/.ssh/config
Host *
ControlMaster		auto
ControlPath		~/.ssh/%r@%h:%p

$ ssh -gTfNL 12345:localhost:12345 host
$ netstat -tln

tcp        0      0 0.0.0.0:12345             0.0.0.0:*
LISTEN      -

$ lsof -n

ssh       182446        user    3u     IPv4           76397177       0t0      TCP 192.168.0.9:51181->192.168.0.15:ssh (ESTABLISHED)
ssh       182446        user    4u     IPv4           76397181       0t0      TCP *:3128 (LISTEN)
ssh       182446        user    5u     IPv6           76397182       0t0      TCP *:3128 (LISTEN)

and similarly:

$ ssh -g host
user at host:~$ exit
$ ssh -gTfNL 12345:localhost:12345 host
$ netstat -tln

tcp        0      0 0.0.0.0:12345             0.0.0.0:*
LISTEN      -

However, if it isn't then -g is ignored on subsequent attempts to
forward ports:

$ ssh host
user at host:~$ exit
$ ssh -g -L 12345:localhost:12345 host
$ netstat -tln

tcp        0      0 127.0.0.1:12345             0.0.0.0:*
LISTEN      -

$ lsof -n

ssh       182399        user    3u     IPv4           76390396       0t0      TCP 192.168.0.9:51178->192.168.0.15:ssh (ESTABLISHED)
ssh       182399        user    4u     unix 0x0000000000000000       0t0 76390976 /home/user/.ssh/user at host
ssh       182399        user    6u     IPv6           76392394       0t0      TCP [::1]:3128 (LISTEN)
ssh       182399        user    7u     IPv4           76392395       0t0      TCP 127.0.0.1:3128 (LISTEN)

This doesn't really make sense: ssh should still be capable of binding
to the correct address as requested.

From:
https://bugs.launchpad.net/debian/+source/openssh/+bug/1259939
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=731950

Reply at:
https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/1259939/comments/2


** Changed in: openssh
       Status: Unknown => Confirmed

** Changed in: openssh
   Importance: Unknown => Low

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https://bugs.launchpad.net/bugs/1259939

Title:
  ssh -g has no effect if master socket already open

Status in Portable OpenSSH:
  Confirmed
Status in “openssh” package in Ubuntu:
  New
Status in “openssh” package in Debian:
  Confirmed

Bug description:
  From the man page:
   -g      Allows remote hosts to connect to local forwarded ports.

  When working with a control socket, this works fine if -g is included
  with the initial connect attempt, for example:

  $ cat ~/.ssh/config
  Host *
  ControlMaster		auto
  ControlPath		~/.ssh/%r@%h:%p

  $ ssh -gTfNL 12345:localhost:12345 host
  $ netstat -tln

  tcp        0      0 0.0.0.0:12345             0.0.0.0:*
  LISTEN      -

  $ lsof -n

  ssh       182446        user    3u     IPv4           76397177       0t0      TCP 192.168.0.9:51181->192.168.0.15:ssh (ESTABLISHED)
  ssh       182446        user    4u     IPv4           76397181       0t0      TCP *:3128 (LISTEN)
  ssh       182446        user    5u     IPv6           76397182       0t0      TCP *:3128 (LISTEN)

  and similarly:

  $ ssh -g host
  user at host:~$ exit
  $ ssh -gTfNL 12345:localhost:12345 host
  $ netstat -tln

  tcp        0      0 0.0.0.0:12345             0.0.0.0:*
  LISTEN      -

  However, if it isn't then -g is ignored on subsequent attempts to
  forward ports:

  $ ssh host
  user at host:~$ exit
  $ ssh -g -L 12345:localhost:12345 host
  $ netstat -tln

  tcp        0      0 127.0.0.1:12345             0.0.0.0:*
  LISTEN      -

  $ lsof -n

  ssh       182399        user    3u     IPv4           76390396       0t0      TCP 192.168.0.9:51178->192.168.0.15:ssh (ESTABLISHED)
  ssh       182399        user    4u     unix 0x0000000000000000       0t0 76390976 /home/user/.ssh/user at host
  ssh       182399        user    6u     IPv6           76392394       0t0      TCP [::1]:3128 (LISTEN)
  ssh       182399        user    7u     IPv4           76392395       0t0      TCP 127.0.0.1:3128 (LISTEN)

  This doesn't really make sense: ssh should still be capable of binding
  to the correct address as requested.

  ProblemType: Bug
  DistroRelease: Ubuntu 12.04
  Package: ssh (not installed)
  ProcVersionSignature: Ubuntu 3.8.0-33.48~precise1-generic 3.8.13.11
  Uname: Linux 3.8.0-33-generic i686
  ApportVersion: 2.0.1-0ubuntu17.6
  Architecture: i386
  Date: Tue Dec 10 12:59:33 2013
  InstallationMedia: Ubuntu-Server 12.04.1 LTS "Precise Pangolin" - Release i386 (20120817.3)
  MarkForUpload: True
  ProcEnviron:
   LANGUAGE=en_GB:en
   TERM=xterm
   PATH=(custom, no user)
   LANG=en_GB.UTF-8
   SHELL=/bin/bash
  SourcePackage: openssh
  UpgradeStatus: No upgrade log present (probably fresh install)

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