Transcript Ncnu.edu.tw

Countermeasures of Spam over Internet
Telephony in SIP.edu
Campuses with MySQL and LDAP
Support
Speaker: Chang-Yu Wu
Adviser: Dr. Quincy Wu
School: National Chi Nan University
Unit: Graduate Institute of CSIE
Date: 2007.10.24
Motivation
 Session Initiation Protocol (SIP), is a
signaling protocol for Internet conferencing,
telephony, events notification and instant
messaging.
 What is VoIP Spam
 The VoIP Spam in the VoIP networks is also
called SPIT (Spam over Internet Telephony).
 It refers to unsolicited calls over VoIP networks.
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Related Work
 Blacklists
 These are lists of e-mail or machine
addresses from which are known to send
spam mails.
 Whitelists
 Lists of addresses from which all mails will be
accepted.
 Spam filtering tools
 SpamAssassin

http://spamassassin.apache.org/
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SIP.edu
 Build a community of Internet2 schools that is
experimenting with enterprise SIP services.
 Users should not be burdened with device
addresses.
 The initial SIP.edu architecture works by
integrating the legacy campus PBX and
person directory.
 The SIP.edu becomes the effective tools
which spammers use for sending SPIT.
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SIP.edu Architecture
INVITE
Alice
(sip:[email protected])
Ncnu.edu.tw
DNS SRV query
_sip._udp.ncnu.edu.tw
INVITE
(sip:[email protected])
Telephone number
where username=bob
Bob’ phone
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SIP.edu Architecture (cont)
INVITE
Alice
(sip:[email protected])
DNS SRV query
_sip._udp.ncnu.edu.tw
Ncnu.edu.tw
INVITE
(sip:[email protected])
Bob’ phone
REGISTER
(Contact: 163.22.21.83)
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SEMS
 SEMS(SIP express media server) is an extensible
media server which helps us adding voice services to
our VoIP system。
SIP server
INVITE
INVITE
200 OK
200 OK
SMTP
mail
IP
Telephone
RTP
SEMS
SMTP
server
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LDAP
 Lightweight Directory Access Protocol (LDAP)
is an application protocol for querying and
modifying directory services running over
TCP/IP.


Optimized for lookups
More easily extended
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System Architecture
 Use SIP.edu to be the basic environment of system.
 Support the function of the Voicemail in the system.
Use SIP.edu?
YES
NO
YES
SIP phone ringing
SIP phone ringing
NO
Campus phone ringing
Voicemail
Register?
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SIP signal
Flow chart
Receive sip
signal
SIP signal
Check
request uri is
local?
YES
Receive local
request uri
NO
Request
uri
Relay the
call
Call
Database
Data
Database
Data
NO
Register?
Use contact list
Service?
YES
YES
NO
SIP phone
ringing
Voicemail
NO
Is Caller’s
number on the
contact list?
YES
YES
Register?
NO
Campus
phone
ringing
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Automatically add callee into the contact list
(1) INVITE Alice
Bob
(6) INVITE Alice
Alice
SIP Proxy
Server
(5) Update Acknowledged
(2) Find Bob’ s Contact list
Contact
xxx xxxxx
xxx xxxxx
(3) Save Alice’s data
in Bob’ s contact list
(4) Update Acknowledged
Bob’ s contact list
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Performance Measurement
 Program codes
 MySQL modules in OpenSER
 MySQL commands from Unix shell scripts
 LDAP commands from Unix shell scripts
 Stress-test
 Call setup scenario (powered by SIPp)




Max Allowed Rate: 10,000 calls
Concurrent Calls: 0~8,000 calls (with interval 200)
Total calls: 20,000 calls
Duration time: 30 s
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Call Failure Rate
100%
Pure SIP
configuration
90%
Failed calls (percent)
80%
70%
Mysql modules in
OpenSER
60%
50%
Mysql commands
from Unix shell
scripts
LDAP commands
from Unix shell
scripts
40%
30%
20%
10%
0%
0
1000
2000
3000
4000
5000
6000
7000
8000
Concurrent calls
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Future work
 Information transmission

Improve call method of storing and searching
data.
 Add data into contact list

Design an interface that allows users to revise
the contact list by themselves.
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Q&A
 Thanks for your coming!
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