SSH VPN not working

[DiskCrasher]

Trying to establish a connection between two networks using SSH:

ssh -NTfv -w any root@192.168.1.98

After logging in, I get the following error:

debug1: Remote: Failed to open the tunnel device.
channel 0: open failed: administratively prohibited: open failed
debug1: channel 0: free: tun, nchannels 1

In the sshd_config file on the server, PermitTunnel is set to "yes".

Any ideas?

[ab@novell.com]

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Hash: SHA1

Wild guess... are you running the 'ssh' command as root? I imagine you
will need to if it is indeed creating a TUN network device for your
system, though admittedly I have no (until two minutes ago) tried this. I
failed until I both enabled PermitTunnel in the sshd_config as well as
initiated the connection with the root user (via sudo).

Good luck.





DiskCrasher wrote:
> Trying to establish a connection between two networks using SSH:
>
> ssh -NTfv -w any root@192.168.1.98
>
> After logging in, I get the following error:
>
> debug1: Remote: Failed to open the tunnel device.
> channel 0: open failed: administratively prohibited: open failed
> debug1: channel 0: free: tun, nchannels 1
>
> In the sshd_config file on the server, PermitTunnel is set to "yes".
>
> Any ideas?
>
>
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[DiskCrasher]

Yes, running as root on both ends.

[hendersj]

On Sun, 25 Oct 2009 19:26:01 +0000, DiskCrasher wrote:

> Trying to establish a connection between two networks using SSH:
>
> ssh -NTfv -w any root@192.168.1.98
>
> After logging in, I get the following error:
>
> debug1: Remote: Failed to open the tunnel device. channel 0: open
> failed: administratively prohibited: open failed debug1: channel 0:
> free: tun, nchannels 1
>
> In the sshd_config file on the server, PermitTunnel is set to "yes".
>
> Any ideas?

Is root permitted to login on the remote system?

Are you using key-based authentication or password-based authentication?

Does a normal ssh to the remote system (ie, 'ssh root@192.168.1.98') work
as expected?

The "administratively prohibited" indicates perhaps that the connection
to the remote system is failing for some reason.

Jim

--
Jim Henderson
openSUSE Forums Moderator

[DiskCrasher]

Answers:

Is root permitted to login on the remote system? Yes.

Are you using key-based authentication or password-based authentication? Password.

Does a normal ssh to the remote system (ie, 'ssh root@192.168.1.98') work as expected? Yes.

I should probably mention that I was attempting this between openSUSE and an NSLU2 device running Linux (with OpenSSH) and also a Windows computer running OpenSSH via Cygwin. Neither worked, but perhaps that's expected using these scenarios? Not sure why that would be.

[hendersj]

On Mon, 26 Oct 2009 23:06:01 +0000, DiskCrasher wrote:

> Answers:
>
> Is root permitted to login on the remote system? Yes.
>
> Are you using key-based authentication or password-based authentication?
> Password.
>
> Does a normal ssh to the remote system (ie, 'ssh root@192.168.1.98')
> work as expected? Yes.
>
> I should probably mention that I was attempting this between openSUSE
> and an NSLU2 device running Linux (with OpenSSH) and also a Windows
> computer running OpenSSH via Cygwin. Neither worked, but perhaps that's
> expected using these scenarios? Not sure why that would be.

One of the suggestions I found while looking into this myself was making
sure port forwarding was allowed. The "administratively denied" message
seems to indicate in most cases that it's a configuration issue, and most
of the issues that I found that were similar reflected that port
forwarding was disabled.

Admittedly, it may not be port forwarding, but could well be something
else in the sshd_config file on the target server.

Which of the two systems is the remote server?

Jim
--
Jim Henderson
openSUSE Forums Moderator

[DiskCrasher]

OpenSUSE is the client. I verified that IP forwarding was enabled by looking at /proc/sys/net/ipv4/ip_forward (set to 1) on the NSLU2. I can forward port 80 to local port 1234 using "ssh -L 1234:localhost:80 root@nslu2".

[hendersj]

On Tue, 27 Oct 2009 00:06:02 +0000, DiskCrasher wrote:

> OpenSUSE is the client. I verified that IP forwarding was enabled by
> looking at /proc/sys/net/ipv4/ip_forward (set to 1) on the NSLU2. I can
> forward port 80 to local port 1234 using "ssh -L 1234:localhost:80
> root@nslu2".

It might help to see the sshd_config file then - with any identifying
information obscured for security purposes.

Jim

--
Jim Henderson
openSUSE Forums Moderator

[DiskCrasher]

Here it is:

#       $OpenBSD: sshd_config,v 1.75 2007/03/19 01:01:29 djm Exp $

# This is the sshd server system-wide configuration file.  See
# sshd_config(5) for more information.

# This sshd was compiled with PATH=/opt/sbin:/opt/bin:/usr/sbin:/usr/bin:/sbin:/
bin

# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented.  Uncommented options change a
# default value.

Port 22
#AddressFamily any
#ListenAddress 0.0.0.0
#ListenAddress ::

# Disable legacy (protocol version 1) support in the server for new
# installations. In future the default will change to require explicit
# activation of protocol 1
Protocol 2

# HostKey for protocol version 1
#HostKey /opt/etc/openssh/ssh_host_key
# HostKeys for protocol version 2
#HostKey /opt/etc/openssh/ssh_host_rsa_key
#HostKey /opt/etc/openssh/ssh_host_dsa_key

# Lifetime and size of ephemeral version 1 server key
#KeyRegenerationInterval 1h
#ServerKeyBits 768

# Logging
# obsoletes QuietMode and FascistLogging
#SyslogFacility AUTH
#LogLevel INFO

# Authentication:

#LoginGraceTime 2m
#PermitRootLogin yes
#StrictModes yes
#MaxAuthTries 6

#RSAAuthentication yes
#PubkeyAuthentication yes
#AuthorizedKeysFile     .ssh/authorized_keys

# For this to work you will also need host keys in /opt/etc/openssh/ssh_known_ho
sts
#RhostsRSAAuthentication no
# similar for protocol version 2
#HostbasedAuthentication no
# Change to yes if you don't trust ~/.ssh/known_hosts for
# RhostsRSAAuthentication and HostbasedAuthentication
#IgnoreUserKnownHosts no
# Don't read the user's ~/.rhosts and ~/.shosts files
#IgnoreRhosts yes

# To disable tunneled clear text passwords, change to no here!
#PasswordAuthentication yes
#PermitEmptyPasswords no

# Change to no to disable s/key passwords
#ChallengeResponseAuthentication yes

# Kerberos options
#KerberosAuthentication no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes
#KerberosGetAFSToken no

# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes

# Set this to 'yes' to enable PAM authentication, account processing,
# and session processing. If this is enabled, PAM authentication will
# be allowed through the ChallengeResponseAuthentication and
# PasswordAuthentication.  Depending on your PAM configuration,
# PAM authentication via ChallengeResponseAuthentication may bypass
# the setting of "PermitRootLogin without-password".
# If you just want the PAM account and session checks to run without
# PAM authentication, then enable this but set PasswordAuthentication
# and ChallengeResponseAuthentication to 'no'.
#UsePAM no

#AllowTcpForwarding yes
#GatewayPorts no
#X11Forwarding no
#X11DisplayOffset 10
#X11UseLocalhost yes
#PrintMotd yes
#PrintLastLog yes
#TCPKeepAlive yes
#UseLogin no
UsePrivilegeSeparation no
#PermitUserEnvironment no
Ciphers arcfour,blowfish-cbc
Compression no
#ClientAliveInterval 0
#ClientAliveCountMax 3
#UseDNS yes
#PidFile /opt/var/run/sshd.pid
#MaxStartups 10
PermitTunnel yes

# no default banner path
#Banner /some/path

# override default of no subsystems
Subsystem       sftp    /opt/libexec/sftp-server

# Example of overriding settings on a per-user basis
#Match User anoncvs
#       X11Forwarding no
#       AllowTcpForwarding no
#       ForceCommand cvs server
#

[hendersj]

On Tue, 27 Oct 2009 02:56:01 +0000, DiskCrasher wrote:

> Here it is:

Nothing immediately jumps out at me - maybe try increasing the loglevel
setting to one of the debug settings and see if any additional messages
pop in the logs.

Perhaps someone else sees something here?

Jim

--
Jim Henderson
openSUSE Forums Moderator