Connect to tunneled VNC via CJDNS, SSH

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This manual is for QubesOS R4.0 - where server is on work machine and client is on personal machine

  • Setup cjdroute.conf
https://wiki.peerfreedom.org/w/How_to_install_and_configure_cjdns_on_Debian-ish_system
  • Setup /etc/ssh/sshd_config
#	$OpenBSD: sshd_config,v 1.100 2016/08/15 12:32:04 naddy Exp $

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

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

# 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 override the
# default value.

AllowUsers tunnel_user

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

HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_ecdsa_key
HostKey /etc/ssh/ssh_host_ed25519_key

# Ciphers and keying
#RekeyLimit default none

# Logging
#SyslogFacility AUTH
#LogLevel INFO

# Authentication:

#LoginGraceTime 2m
#PermitRootLogin prohibit-password
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10

#PubkeyAuthentication yes

# Expect .ssh/authorized_keys2 to be disregarded by default in future.
#AuthorizedKeysFile	.ssh/authorized_keys .ssh/authorized_keys2

#AuthorizedPrincipalsFile none

#AuthorizedKeysCommand none
#AuthorizedKeysCommandUser nobody

# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
#HostbasedAuthentication no
# Change to yes if you don't trust ~/.ssh/known_hosts for
# 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 no
#PermitEmptyPasswords no

# Change to yes to enable challenge-response passwords (beware issues with
# some PAM modules and threads)
ChallengeResponseAuthentication no

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

# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes
#GSSAPIStrictAcceptorCheck yes
#GSSAPIKeyExchange no

# 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 yes

#AllowAgentForwarding yes
AllowTcpForwarding yes
#GatewayPorts no
X11Forwarding yes
X11DisplayOffset 10
X11UseLocalhost yes
#PermitTTY yes
PrintMotd no
#PrintLastLog yes
TCPKeepAlive yes
#UseLogin no
#UsePrivilegeSeparation sandbox
#PermitUserEnvironment no
#Compression delayed
ClientAliveInterval 5
ClientAliveCountMax 300
#UseDNS no
#PidFile /var/run/sshd.pid
#MaxStartups 10:30:100
#PermitTunnel no
#ChrootDirectory none
#VersionAddendum none

# no default banner path
#Banner none

# Allow client to pass locale environment variables
AcceptEnv LANG LC_*

# override default of no subsystems
Subsystem	sftp	/usr/lib/openssh/sftp-server

# Example of overriding settings on a per-user basis
#Match User anoncvs
#	X11Forwarding no
#	AllowTcpForwarding no
#	PermitTTY no
#	ForceCommand cvs server
  • Setup IPv6 firewall using ip6tables tool - this example is for 1 IPv6 host, 22 is for SSH and for rest ports use the same chainrule
-D INPUT -j DROP
-A INPUT -s [cjdns_client]/128 -d [cjdns_server]/128 -i tun0 -p tcp -m tcp --dport 22 -j ACCEPT
-A INPUT -j DROP
  • Add user
useradd -m -s /bin/false tunnel_user
  • Setup permissions for account
sudo chown tunnel_user:tunnel_user /home/tunnel_user/.ssh
sudo chown tunnel_user:tunnel_user /home/tunnel_user/.ssh/authorized_keys
sudo chmod 0700 /home/tunnel_user/.ssh
sudo chmod 0644 /home/tunnel_user/.ssh/authorized_keys
  • Add public key from example 'QubesIncoming/personal/id_ed25519.pub'
/home/tunnel_user/.ssh/authorized_keys
  • Start the servers

- CJDNS

sudo ./cjdroute < cjdroute.conf

- SSH

sudo systemctl start ssh.service

- X11VNC

x11vnc -safer -viewonly -shared -loop -nopw -localhost -display :0 -auth /home/tunnel_user/.Xauthority

And on client:

1. Generate the ed25519 key : ssh-keygen -t ed25519
2. Copy public key to work machine and add content to authorized_keys : qvm-copy .ssh/id_ed25519.pub
3. Start the ssh with local tunnel option : ssh -N -L 15900:localhost:5900 tunnel_user@[cjdns_ipv6]
4. Start the VNC client : vncviewer localhost:15900