RADIUS auth

This document contains GW setup information for initial implementation of RADIUS authentication when logging in over ssh (currently under development).

1. In order for ssh to use pam modules, /etc/sshd_config needs to be modified.

Modified example of /etc/sshd_config

#    $OpenBSD: sshd_config,v 1.82 2010/09/06 17:10:19 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 change a
# default value.

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

# The default requires explicit activation of protocol 1
#Protocol 2

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

# Lifetime and size of ephemeral version 1 server key
#KeyRegenerationInterval 1h
#ServerKeyBits 1024

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

# Authentication:

#LoginGraceTime 2m
PermitRootLogin no
#StrictModes yes
#MaxAuthTries 6
#MaxSessions 10

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

# For this to work you will also need host keys in /etc/ssh_known_hosts
#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 yes

#AllowAgentForwarding yes
#AllowTcpForwarding yes
#GatewayPorts no
#X11Forwarding no
#X11DisplayOffset 10
#X11UseLocalhost yes
#PrintMotd yes
#PrintLastLog yes
#TCPKeepAlive yes
#UseLogin no
#UsePrivilegeSeparation yes
#PermitUserEnvironment no
#Compression delayed
#ClientAliveInterval 0
#ClientAliveCountMax 3
UseDNS no
#PidFile /var/run/sshd.pid
#MaxStartups 10
#PermitTunnel no
#ChrootDirectory none

# no default banner path
#Banner none

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

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

Below are the differences between default sshd_config file from the device and the above example:

--- sshorig     2015-11-19 10:53:05.279666948 +0200
+++ sshpam      2015-11-19 10:50:07.415666377 +0200
@@ -61,7 +61,7 @@
 #PermitEmptyPasswords no
 
 # Change to no to disable s/key passwords
-#ChallengeResponseAuthentication yes
+ChallengeResponseAuthentication yes
 
 # Kerberos options
 #KerberosAuthentication no
@@ -82,7 +82,7 @@
 # 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
+UsePAM yes
 
 #AllowAgentForwarding yes
 #AllowTcpForwarding yes

2. Create /etc/pam.d directory and a file named sshd

/etc/pam.d/sshd

auth       sufficient      pam_radius_auth.so debug
auth       include      system-auth
account    sufficient      pam_radius_auth.so debug
account    required     pam_nologin.so
account    include      system-auth
password   include      system-auth
session    sufficient      pam_radius_auth.so debug conf=/etc/raddb/server
session    optional     pam_keyinit.so force revoke
session    include      system-auth
session    required     pam_loginuid.so

3. Create /etc/raddb/ directory and a file named 'server' /etc/raddb/server file contains a list on server information needed by the pam radius client.

The example contents of the /etc/raddb/server file for my test radius server

10.0.0.199 martem-radius 20

/etc/raddb/server structure explained: SERVER-IP SECRET SECONDS-TO-WAIT

NB! ATM there must a local user with the same name as the one which will be used when authenticating using RADIUS server