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Old 10-31-2011, 11:35 AM   #1
Mark_667
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Specifying ciphers for SSH


I'm trying to get ssh on OpenSolaris to work with plink with the -ssh option. Plink can use the following ciphers:
aes128-ctr,aes192-ctr,aes256-ctr,arcfour128,arcfour256,arcfour

SSH v2:
'aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour'

I tried specifying the v2 ciphers in my /etc/ssh/sshd_config file (see below) but after restarting the service I get a connection refused, even after changing it back and restarting it again. Can anyone tell me where I'm going wrong here?
Code:
#
# Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
# Use is subject to license terms.
#
# Configuration file for sshd(1m)

# Protocol versions supported
#
# The sshd shipped in this release of Solaris has support for major versions
# 1 and 2.  It is recommended due to security weaknesses in the v1 protocol
# that sites run only v2 if possible. Support for v1 is provided to help sites
# with existing ssh v1 clients/servers to transition. 
# Support for v1 may not be available in a future release of Solaris.
#
# To enable support for v1 an RSA1 key must be created with ssh-keygen(1).
# RSA and DSA keys for protocol v2 are created by /etc/init.d/sshd if they
# do not already exist, RSA1 keys for protocol v1 are not automatically created.

# Uncomment ONLY ONE of the following Protocol statements.

# Only v2 (recommended)
#Protocol 2

# Both v1 and v2 (not recommended)
Protocol 2,1

# Only v1 (not recommended)
#Protocol 1

# Listen port (the IANA registered port number for ssh is 22)
Port 22

# The default listen address is all interfaces, this may need to be changed
# if you wish to restrict the interfaces sshd listens on for a multi homed host.
# Multiple ListenAddress entries are allowed.

# IPv4 only
#ListenAddress 0.0.0.0
# IPv4 & IPv6
ListenAddress ::

# Port forwarding
AllowTcpForwarding no

# If port forwarding is enabled, specify if the server can bind to INADDR_ANY. 
# This allows the local port forwarding to work when connections are received
# from any remote host.
GatewayPorts no

# X11 tunneling options
X11Forwarding yes
X11DisplayOffset 10
X11UseLocalhost yes

# The maximum number of concurrent unauthenticated connections to sshd.
# start:rate:full see sshd(1) for more information.
# The default is 10 unauthenticated clients.
#MaxStartups 10:30:60

# Banner to be printed before authentication starts.
#Banner /etc/issue

# Should sshd print the /etc/motd file and check for mail.
# On Solaris it is assumed that the login shell will do these (eg /etc/profile).
PrintMotd no

# KeepAlive specifies whether keep alive messages are sent to the client.
# See sshd(1) for detailed description of what this means.
# Note that the client may also be sending keep alive messages to the server.
KeepAlive yes

# Syslog facility and level 
SyslogFacility auth
LogLevel info

#
# Authentication configuration
# 

# Host private key files
# Must be on a local disk and readable only by the root user (root:sys 600).
HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_dsa_key

# Length of the server key
# Default 768, Minimum 512
ServerKeyBits 768

# sshd regenerates the key every KeyRegenerationInterval seconds.
# The key is never stored anywhere except the memory of sshd.
# The default is 1 hour (3600 seconds).
KeyRegenerationInterval 3600

# Ensure secure permissions on users .ssh directory.
StrictModes yes

# Length of time in seconds before a client that hasn't completed
# authentication is disconnected.
# Default is 600 seconds. 0 means no time limit.
LoginGraceTime 600

# Maximum number of retries for authentication
# Default is 6. Default (if unset) for MaxAuthTriesLog is MaxAuthTries / 2
MaxAuthTries	6
MaxAuthTriesLog	3

# Are logins to accounts with empty passwords allowed.
# If PermitEmptyPasswords is no, pass PAM_DISALLOW_NULL_AUTHTOK 
# to pam_authenticate(3PAM).
PermitEmptyPasswords no

# To disable tunneled clear text passwords, change PasswordAuthentication to no.
PasswordAuthentication yes

# Use PAM via keyboard interactive method for authentication.
# Depending on the setup of pam.conf(4) this may allow tunneled clear text
# passwords even when PasswordAuthentication is set to no. This is dependent
# on what the individual modules request and is out of the control of sshd
# or the protocol.
PAMAuthenticationViaKBDInt yes

# Are root logins permitted using sshd.
# Note that sshd uses pam_authenticate(3PAM) so the root (or any other) user
# maybe denied access by a PAM module regardless of this setting.
# Valid options are yes, without-password, no.
PermitRootLogin yes

# sftp subsystem
Subsystem	sftp	/usr/lib/ssh/sftp-server


# SSH protocol v1 specific options
#
# The following options only apply to the v1 protocol and provide
# some form of backwards compatibility with the very weak security
# of /usr/bin/rsh.  Their use is not recommended and the functionality
# will be removed when support for v1 protocol is removed.

# Should sshd use .rhosts and .shosts for password less authentication.
IgnoreRhosts yes
RhostsAuthentication no

# Rhosts RSA Authentication
# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts.
# If the user on the client side is not root then this won't work on
# Solaris since /usr/bin/ssh is not installed setuid.
RhostsRSAAuthentication no

# Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication.
#IgnoreUserKnownHosts yes

# Is pure RSA authentication allowed.
# Default is yes
RSAAuthentication yes

# SSH protocol v2 specific options
Ciphers ''aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,
		 aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,
		 aes256-cbc,arcfour''
 
Old 10-31-2011, 11:47 AM   #2
Blinker_Fluid
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Registered: Jul 2003
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When I've messed with Ciphers in the past I usually just uncommented the existing line that is commented out by default:
Code:
Ciphers        aes128-ctr,aes128-cbc,arcfour,3des-cbc,blowfish-cbc

by default the section just looks like this:

# Default Encryption algorithms and Message Authentication codes
#Ciphers        aes128-ctr,aes128-cbc,arcfour,3des-cbc,blowfish-cbc
#MACS   hmac-md5,hmac-sha1,hmac-sha1-96,hmac-md5-96
It looks like there is some quote marks that may be throwing the daemon off or it's in the wrong area.
 
Old 10-31-2011, 12:49 PM   #3
Mark_667
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Location: Manchester, England
Distribution: Ubuntu 20.04
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I tried commenting out the Ciphers part and replacing it with teh Ciphers line you mention but I'm still getting a connection refused when I try to connect.

#svcs -d ssh
STATE STIME FMRI
disabled Oct_17 svc:/network/physical:default
disabled Oct_17 svc:/network/ipfilter:default

all the others are online, svcadm enable ssh doesn't make any difference, what would cause this?
 
Old 10-31-2011, 01:31 PM   #4
Blinker_Fluid
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Quote:
Originally Posted by Mark_667 View Post
I tried commenting out the Ciphers part and replacing it with teh Ciphers line you mention but I'm still getting a connection refused when I try to connect.

#svcs -d ssh
STATE STIME FMRI
disabled Oct_17 svc:/network/physical:default
disabled Oct_17 svc:/network/ipfilter:default

all the others are online, svcadm enable ssh doesn't make any difference, what would cause this?
svc:/network/physical:default is disabled? Do you have link light in the back? What does 'dladm show-dev' show? Normally it's online on the systems I work on (I've never noticed it in a disabled state).
 
Old 11-01-2011, 05:16 AM   #5
Mark_667
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Registered: Aug 2005
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Distribution: Ubuntu 20.04
Posts: 383

Original Poster
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My box just spits out a usage screen when I try dladm show-dev but

Code:
#dladm show-link
LINK	CLASS	MTU	STATE	OVER
dnet0	phys	1500	unknown	--
 
  


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