FREERADIUS WITH MIKROTIK – Part #16 – Loosy workaround to disconnect missing users from the NAS

FREERADIUS WITH MIKROTIK – Part #1 – General Tip’s Click here to read more on FR tutorials …

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Disclaimer! This is important!

Every Network is different , so one solution cannot be applied to all. Therefore try to understand the logic & create your own solution as per your network scenario. Just dont follow copy paste.

If anybody here thinks I am an expert on this stuff, I am NOT certified in anything Mikrotik/Cisco/Linux or Windows. However I have worked with some core networks and I read , research & try stuff all of the time. So I am not speaking/posting about stuff I am formerly trained in, I pretty much go with experience and what I have learned on my own. And , If I don’t know something then I read & learn all about it.

So , please don’t hold me/my-postings to be always 100 percent correct. I make mistakes just like everybody else. However – I do my best, learn from my mistakes and always try to help others.

Regard's
Syed Jahanzaib~

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Scenario:

We have single NAS (Mikrotik) as pppoe server along with Freeradius as AAA server.
In NAS we have configured INTERIM UIPDATES set to 5 minutes therefore it sends accounting packets to the freeradius server after every 5 minutes. In Freeradius server web have a BASH script that closes the online sessions if the FR doesnt receive  accounting packets from the NAS for more then 10 minutes (to clear false sessions by considering that NAS is powered off).

We also have some users created locally in the NAS.

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Problem:

Sometimes dueto communication disruption , Freeradius close the user session in radacct table considering the NAS is not reachable, BUT the user is still active on the NAS. When the communication restores & NAS sends the existing users accounting packets to the freeradius, they get discarded because the NAS connected user Account-Session-ID does not matches with the radacct table session id.

Freeradius will create new session (with acctstoptime is NULL value) only when

• If new connection is made by user end , OR
• If NAS connected user session ID is matched with the radacct Account Session ID

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Workaround:

This is not a proper solution because it is limited to single NAS only, for multi NAS you should search freeradius mailing list for better approach.

Following is bash script which performs following action …

1. Fetch NAS online active users in PPP/Active Connections, using password less ssh login from the Linux to Mikrotik,
2. Fetch Freeradius online active users from RADACCT table (where acctstoptime value is NULL),
3. Display difference between NAS and Freeradius Online users,
4. If differentiated user is NAS local user, then donot take any action just move on,
5. ELSE consider this user as RADIUS user which is online in NAS but offline in Radius RADACCT table, therefore KICK it , so that it can re-establish the new session and get re-inserted in radacct table properly.

You can modify it as per you local requirements.

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Requirements:

• Mikrotik as NAS with SSH enabled & RSA key imported so that ssh from Linux to mikrotik must work without password, explained  here , Make sure its working
• Freeradius Server
• Arithmetic function is performed by BC command, make sure you have it installed

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the Script!

Schedule the script to run every 5 or above minutes, or as per local requirement,

#!/bin/bash
# BASH script to fetch online users list from Mikrotik NAS & compare it with local FR online users
# IF difference found, then kick the missed users from NAS, but if user is NAS local , then skip it
# This way the missing users will re-establishes there session and will be inserted properly in radacct table AGAIN ,
# This is just a workaround only, ITs not a proper solution, It also assumes you have single NAS only
# Created on : 11-JUL-2018
# Syed Jahanzaib / aacable at hotmnail dot com / https://aacable dot wordpress dot com

#set -x
# Setting various variables ...

# MYSQL related data
SQLID="root"
SQLPASS="SQLROOTPASSWORD"
DB="radius"
TBL_LOG="log"
export MYSQL_PWD=$SQLPASS
FOOTER="Script Ends Here. Thank you
Syed Jahanzaib / aacable at hotmail dot com"
# MIKROTIK related Data
MT_USER="admin"
MT_IP="10.10.0.1"
MT_PORT="10022"
MT_SECRET="RADIUS_INCOMING_SECRET"
MT_COA_PORT="3799"

# SSH commands for Mikrotik & Freeradius
MT_SSH_CMD="ssh $MT_USER@$MT_IP -p $MT_PORT"
FR_SSH_CMD="mysql -uroot --skip-column-names -s -e"

# Temporary holder for various data
MT_ACTIVE_USERS_LIST="/tmp/mt_active_users.txt"
MT_ACTIVE_USERS_NAME_ONLY_LIST="/tmp/mt_active_users_name_only_list.txt"
FR_ACTIVE_USERS_LIST="/tmp/fr_active_users_list.txt"
FR_MISSING_USERS_NAME_LIST="/tmp/fr_active_users_missing_list.txt"
> $MT_ACTIVE_USERS_LIST
> $MT_ACTIVE_USERS_NAME_ONLY_LIST
> $FR_ACTIVE_USERS_LIST
> $FR_MISSING_USERS_NAME_LIST

# Execute SSH commands & store data in temporary holders
echo "1- Getting list of Mikrotik Online users via ssh ..."
$MT_SSH_CMD "/ppp active print terse " | sed '/^\s*$/d' > $MT_ACTIVE_USERS_LIST
echo "2- Getting list of Freeradius Online users from 'RADACCT' table ..."
$FR_SSH_CMD "use radius; select username from radacct WHERE acctstoptime IS NULL;" > $FR_ACTIVE_USERS_LIST

# Run loop forumla to run CMD for single or multi usernames
echo "3- Running loop formula to fetch usernames only from the mikrotik PPP online users list ..."
num=0
cat $MT_ACTIVE_USERS_LIST | while read users
do
num=$[$num+1]
USERNAME=`echo $users |sed -n -e 's/^.*name=//p' | awk '{print $1}'`
echo "$USERNAME" >> $MT_ACTIVE_USERS_NAME_ONLY_LIST
done

# calculate and display Users from Mikrotik Active PPP list vs Freeradius Local Actvive Users List
MT_USERS_COUNT=`cat $MT_ACTIVE_USERS_LIST | wc -l`
FR_USERS_COUNT=`cat $FR_ACTIVE_USERS_LIST | wc -l`
USER_DIFFERENCE=`echo "($MT_USERS_COUNT)-($FR_USERS_COUNT)" |bc`
echo "
Result:
echo MIKROTIK ACTIVE USERS = $MT_USERS_COUNT
echo RADIUS ACTIVE USERS = $FR_USERS_COUNT
echo Freeradius Missing Users = $USER_DIFFERENCE
"
#comm -23 <(sort < $MT_ACTIVE_USERS_NAME_ONLY_LIST) <(sort < $FR_ACTIVE_USERS_LIST)

# Make separate list for users that are foung missing in Freeradius online users list
comm -23 <(sort < $MT_ACTIVE_USERS_NAME_ONLY_LIST) <(sort  $FR_MISSING_USERS_NAME_LIST

# Check if missing user is NAS local or FR user
echo "4- Running loop formula to check if missing users from FR are NAS local or radius users ...
"
cat $FR_MISSING_USERS_NAME_LIST | while read users
do
num=$[$num+1]
USERNAME=`echo $users | awk '{print $1}'`
REMOTE_OR_LOCAL=`cat $MT_ACTIVE_USERS_LIST |grep $USERNAME |awk '{print $2}'`
if [ "$REMOTE_OR_LOCAL" != "R" ]; then
echo "$USERNAME = This user is ON-LINE in NAS but OFF-LINE in FR radacct table, BUT its NAS local user, so skipping it ..."
else
# IF user is a FR user, then consider his MISSED user & kick him so that he will reconnect & proper entries will be made in radius radacct table
echo "$USERNAME = This user is ON-LINE in NAS, but OFF-LINE in FR radacct table, kicking it so it will reconnect & session will be recreated properly **********"
#$MT_SSH_CMD "/ppp active remove [find name=$USERNAME]"
# KICK user via RADCLIENT / zaib
echo user-name=$USERNAME | radclient -x $MT_IP:$MT_COA_PORT disconnect $MT_SECRET
$FR_SSH_CMD "use $DB; INSERT into $TBL_LOG (data, msg) VALUES ('$USERNAME', '$USERNAME - Kicked from NAS dueto missing session in FR');"
fi
done

echo "$FOOTER"

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OUTPUT:

root@zaibradius:/temp# ./test.sh
1- Getting list of Mikrotik Online users via ssh ...
2- Getting list of Freeradius Online users from 'RADACCT' table ...
3- Running loop formula to fetch usernames only from the mikrotik PPP online users list ...

Result:
echo MIKROTIK ACTIVE USERS = 959
echo RADIUS ACTIVE USERS = 945
echo Freeradius Missing Users = 14

4- Running loop formula to check if missing users from FR are NAS local or radius users ...

USER1 = This user is ON-LINE in NAS but OFF-LINE in FR radacct table, BUT its NAS local user, so skipping it ...
USER2 = This user is ON-LINE in NAS but OFF-LINE in FR radacct table, BUT its NAS local user, so skipping it ...
USER3 = This user is ON-LINE in NAS but OFF-LINE in FR radacct table, BUT its NAS local user, so skipping it ...
USER4 = This user is ON-LINE in NAS but OFF-LINE in FR radacct table, BUT its NAS local user, so skipping it ...
USER5 = This user is ON-LINE in NAS but OFF-LINE in FR radacct table, BUT its NAS local user, so skipping it ...
USER6 = This user is ON-LINE in NAS but OFF-LINE in FR radacct table, BUT its NAS local user, so skipping it ...
USER7 = This user is ON-LINE in NAS but OFF-LINE in FR radacct table, BUT its NAS local user, so skipping it ...
USER8 = This user is ON-LINE in NAS but OFF-LINE in FR radacct table, BUT its NAS local user, so skipping it ...
USER9 = This user is ON-LINE in NAS but OFF-LINE in FR radacct table, BUT its NAS local user, so skipping it ...
USER10 = This user is ON-LINE in NAS but OFF-LINE in FR radacct table, BUT its NAS local user, so skipping it ...
USER11 = This user is ON-LINE in NAS but OFF-LINE in FR radacct table, BUT its NAS local user, so skipping it ...
USER12 = This user is ON-LINE in NAS but OFF-LINE in FR radacct table, BUT its NAS local user, so skipping it ...
USER13 = This user is ON-LINE in NAS but OFF-LINE in FR radacct table, BUT its NAS local user, so skipping it ...
USER14 = This user is ON-LINE in NAS, but OFF-LINE in FR radacct table, kicking it so it will reconnect & session will be recreated properly **********

Sending Disconnect-Request of id 95 to 10.10.0.1 port 3799
User-Name = "USER14"
rad_recv: Disconnect-ACK packet from host 10.10.0.1 port 3799, id=95, length=36
NAS-Identifier = "MikroTik"
NAS-IP-Address = 10.10.0.1

Script Ends Here. Thank you
Syed Jahanzaib / aacable at hotmail dot com

.

Kick action entry will be logged in LOG table,

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Salam Alykum,