mikrotik_snippets/linux/radius-client.txt

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### Linux radius client
# Notes:
For user authentication to a radius server,
linux need the local user exist. The pam-radius
module not create the local user automatically.
To create the local user automatically:
Enable the pam-radius module.
Enable rsyslog and cron.
The user try to login the first time (and fail).
The the ssh daemon log the incident.
Cron execute a script every minute:
Read the log file and find the username.
Verify the existence of the user with the radius server.
Create the local user.
The user can login now.
# Install libpam-radius-auth and radius-utils
apt-get install libpam-radius-auth freeradius-utils
# Edit /etc/pam_radius_auth.conf
Add the radius server:
SERVER_IP_ADDRESS PRESHARED-KEY TIMEOUT
# Edit /etc/pam.d/sshd
# Edit /etc/pam.d/sudo
First line add:
auth sufficient pam_radius_auth.so
# Edit /etc/ssh/sshd_config
Change:
SyslogFacility LOCAL6
LogLevel INFO
# Edit /etc/rsyslog.conf
Add:
local6.* -/var/log/sshd.log
# Enable rsyslog and cron
systemctl enable rsyslog.service
systemctl enable cron.service
# Add the radius group
addgroup --system radius
# Create the base dir for homes
mkdir /radius
chmod 755 /radius
# Create the script /usr/local/bin/userradius.sh
Change RADIUSIP and RADIUSPSK
#!/bin/bash
RADIUSIP='RADIUS_IP_ADDR'
RADIUSPSK='RADIUS_PASSWORD'
SSHLOG='/var/log/sshd.log'
PATH='/usr/sbin:/usr/bin:/sbin:/bin'
DIRHME='/radius'
LOGFILE='/var/log/radius.log'
if [ -s "$SSHLOG" ]; then
DNOW=`date '+%d/%m/%Y %H:%M:%S'`
cat "$SSHLOG" | grep 'input_userauth_request' | sed -e 's/invalid user /|/' -e 's/ \[preauth\]/|/' | cut -d '|' -f 2 | tr '[A-Z]' '[a-z]' | tr -d '[:blank:]' | sort | uniq | while read NAMEUSR; do
VALIDATE=`radtest "$NAMEUSR" 'DUMMYPASS' "$RADIUSIP" '1812' "$RADIUSPSK" 2> /dev/null | grep 'Bad Encrypted password'`
if [ ! -z "$VALIDATE" ]; then
if [ ! -d "${DIRHME}/${NAMEUSR}" ]; then
VALIDATE=`cat /etc/passwd | grep ^${NAMEUSR}`
if [ -z "$VALIDATE" ]; then
useradd -d "${DIRHME}/${NAMEUSR}" -g 'radius' -m -N -s '/bin/bash' "$NAMEUSR"
chmod 700 "${DIRHME}/${NAMEUSR}"
echo "${DNOW} - NAMEUSR creado: $NAMEUSR" >> "$LOGFILE"
chmod 600 "$LOGFILE"
fi
fi
fi
done
truncate -s 0 "$SSHLOG"
fi
# Make script executable
chmod 750 /usr/local/bin/userradius.sh
# Add the script to /etc/crontab
* * * * * root /usr/local/bin/userradius.sh > /dev/null 2> /dev/null
# Reboot