120 slides mapping the internet and intranets steve branigan, hal burch, bill cheswick...
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120 slides
Mapping the Internet and
Intranets
Steve Branigan, Hal Burch, Bill Cheswick
ches@lumeta.com
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Motivations
• Intranets are out of control– Always have been
• Highlands “day after” scenario
• Panix DOS attacks– a way to trace
anonymous packets back!
• Internet tomography
• Curiosity about size and growth of the Internet
• Same tools are useful for understanding any large network, including intranets
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The Original Project
• Long term reliable collection of Internet and Lucent connectivity information– without annoying
too many people
• Attempt some simple visualizations of the data
– movie of Internet growth!
• Develop tools to probe intranets
• Extended database for researchers
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Uses for the Internet data
• topography studies
• long-term routing studies
• publicly available database– (“open source”) for spooks
• interesting database for graph theorists
• combine with other mappers to make an actual map of the Internet
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History of the Project
• Started in August 1998 at Bell Labs
• April-June 1999: Yugoslavia mapping
• July 2000: first customer intranet scanned
• Sept. 2000: spun off Lumeta from Lucent/Bell Labs
• June 2002: “B” round funding completed
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Related Work
• See Martin Dodge’s cyber geography page
• MIDS - John Quarterman
• CAIDA - kc claffy
• Mercator
• Enter “internet map” in your search engine
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Methods - data collection
• Single reliable host connected at the company perimeter
• Daily full scan of Lucent
• Daily partial scan of Internet, monthly full scan
• One line of text per network scanned– Unix tools
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Methods - network scanning
• Obtain master network list– network lists from Merit, RIPE, APNIC, etc.– BGP data or routing data from customers– hand-assembled list of Yugoslavia/Bosnia
• Run a traceroute-style scan towards each network
• Stop on error, completion, no data– Keep the natives happy
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Daily database
• 100-200MB of text
• compresses to 5-10MB
• daily Internet results available from mapping web page– have not checked to see who gets it!
• Saved to different partition, and offloaded to other secure computer
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Traceroute
• Probes toward each target network with increasing TTL
• Probes are ICMP, UDP, TCP to port 80, 25, 139, etc.
• Some people block UDP, others ICMP
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Traceroute
Application level
TCP/UDP
IP
Hardware
Client
IP
Hardware
Router
IP
Hardware
Router
IP
Hardware
Router
IP
Hardware
Router
IP
Hardware
Router
Application level
TCP/UDP
IP
Hardware
Server
Hop 1 Hop 2 Hop 3
Hop 3Hop 4
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Send a packet with a TTL of 1…
Application level
TCP/UDP
IP
Hardware
Client
IP
Hardware
Router
IP
Hardware
Router
IP
Hardware
Router
IP
Hardware
Router
IP
Hardware
Router
Application level
TCP/UDP
IP
Hardware
Server
Hop 1 Hop 2 Hop 3
Hop 3Hop 4
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…and we get the death notice from the first hop
Application level
TCP/UDP
IP
Hardware
Client
IP
Hardware
Router
IP
Hardware
Router
IP
Hardware
Router
IP
Hardware
Router
IP
Hardware
Router
Application level
TCP/UDP
IP
Hardware
Server
Hop 1 Hop 2 Hop 3
Hop 3Hop 4
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Send a packet with a TTL of 2…
Application level
TCP/UDP
IP
Hardware
Client
IP
Hardware
Router
IP
Hardware
Router
IP
Hardware
Router
IP
Hardware
Router
IP
Hardware
Router
Application level
TCP/UDP
IP
Hardware
Server
Hop 1 Hop 2 Hop 3
Hop 3Hop 4
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… and so on …
Application level
TCP/UDP
IP
Hardware
Client
IP
Hardware
Router
IP
Hardware
Router
IP
Hardware
Router
IP
Hardware
Router
IP
Hardware
Router
Application level
TCP/UDP
IP
Hardware
Server
Hop 1 Hop 2 Hop 3
Hop 3Hop 4
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Advantages
• We don’t need access (I.e. SNMP) to the routers
• It’s very fast
• Standard Internet tool: it doesn’t break things
• Insignificant load on the routers
• Not likely to show up on IDS reports
• We can probe with many packet types
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Limitations
• Outgoing paths only
• View is from scanning host only
• Takes a while to collect alternating paths
• Gentle mapping means missed endpoints
• Imputes non-existent links
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The data can go either way
A
E F
D
B C
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The data can go either way
A
E F
D
B C
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But our test packets only go part of the way
A
E F
D
B C
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We record the hop…
A
E F
D
B C
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The next probe happens to go the other way
A
E F
D
B C
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…and we record the other hop…
A
E F
D
B C
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We’ve imputed a link that doesn’t exist
A
E F
D
B C
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Remediations
• Alternate routes not a factor on intranets
• Scan from several sources
• “stitching” needed– Traceroute in different directions gives
different interface IP addresses– Techniques needed to link multiple IP
addresses to a single host machine
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Network scanning
• Custom program
• Concurrently scans towards 500 nets at once
• Throttled to 400 packets/sec– 100 p/s over dialup modems!
• Slow daily scan for host on destination network
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Data collection complaints
• Australian parliament was the first to complain
• List of whiners (25 nets)
• Military noticed immediately– Steve Northcutt– arrangements/warnings to DISA and CERT
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Visualization goals
• make a map– show interesting features– debug our database and collection
methods– hard to fold up
• geography doesn’t matter
• use colors to show further meaning
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Colored byAS number
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Map Coloring
• distance from test host
• IP address– shows communities
• Geographical (by TLD)
• ISPs
• future– timing, firewalls, LSRR blocks
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Colored by IP address!
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Colored by geography
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Colored by ISP
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Colored by distancefrom scanning host
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US militaryreached by ICMP ping
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US military networksreached by UDP
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Yugoslavia
An unclassified peek at a new battlefield
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Un film par Steve “Hollywood” Branigan...
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fin
120 slides
NYC after 9/11
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CIDR and IP Counts
145K
150K
155K
160K
165K
170K
175K
180K
9/11 9/12 9/13 9/14 9/15 9/16 9/17 9/18 9/19 9/20 9/21 9/22
Date
Cou
nt
# Edges# CIDRs# IPs
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Routers in New York City
1000
1100
1200
1300
1400
9/11 9/12 9/13 9/14 9/15 9/16 9/17 9/18 9/19 9/20 9/21 9/22
Date
# R
ou
ters
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Internet before 9/11/2001
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Internet after 9/11/2001
120 slides
Let’s look at some intranets
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Anything large enough to be called
an “intranet” isout of control
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This is not the fault of network administrators!
• Robust internet design frustrates central control– Ad hoc growth– Mergers and acquisitions frustrate
long-term network planning and policies
• CIOs and auditors already know this
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We call these “routing leaks”
• Easily-found holes in the intranet perimeter
• Show up nicely on the maps
• Leaking hosts or routers announce routes to other networks or the Internet
• Sometimes left over from an old corporate split
• Non-functional VPNs can show up
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This wasSupposedTo be aVPN
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The maps are useful, but not the main data
• We collect tens of megabytes of network data
• There were unexpected subtleties to this process
• How do you display all this information, given that different clients want different data?
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The second technology: host leak detection
• Developed to find hosts that have access to both intranet and Internet
• Or across any privilege boundary
• Leaking hosts do not route between the networks
• May be a dual-homed host
• Not always a bad thing
• Technology didn’t exist to find these
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Possible host leaks
• Miss-configured telecommuters connecting remotely
• VPNs that are broken
• DMZ hosts with too much access
• Business partner networks
• Internet connections by rogue managers
• Modem links to ISPs
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Leak results
• Found home web businesses
• At least two clients have tapped leaks– One made front page news
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Leak Detection Prerequisites
• List of potential leakers: obtained by census
• Access to intranet
• Simultaneous availability of a “mitt”
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Leak Detection Layout
Internet intranet
Mapping hostA
Test hostB
mittD
C
• Mapping host with address A is connected to the intranet
• Mitt with address D has Internet access
• Mapping host and mitt are currently the same host, with two interfaces
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Leak Detection
Internet intranet
Mapping hostA
Test hostB
mittD
C
• Test host has known address B on the intranet
• It was found via census
• We are testing for unauthorized access to the Internet, possibly through a different address, C
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Leak Detection
Internet intranet
Mapping hostA
Test hostB
mittD
C
• A sends packet to B, with spoofed return address of D
• If B can, it will reply to D with a response, possibly through a different interface
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Leak Detection
Internet intranet
Mapping hostA
Test hostB
mittD
C
• Packet must be crafted so the response won’t be permitted through the firewall
• A variety of packet types and responses are used
• Either inside or outside address may be discovered
• Packet is labeled so we know where it came from
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Leak Detection
Internet intranet
Mapping hostA
Test hostB
mittD
C
• This describes outbound leaks
• Inbound leaks are usually much more serious
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Possible problems
• NAT
• egress filtering
• transit of sensitive data over the public networks
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Our new tools give new views of intranets
• The pictures are mostly for management
• Maps can show progress– red is bad, blue is good– we can color the maps in many ways
• The real value in the reports is the list of anomalies– network leaks, routing loops, open
routers, etc.
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How we scan
• Via dialup, using RAS servers
• Secure tunnel, if you prefer– IP/SEC– PPTP– others?
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What we do
• Probe the network for things not in the official list
• Run a host enumeration
• Run leak tests on each host found
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Technology used
• Traceroute
• SNMP queries– Router type– Routing tables
• Pings
• Special leak detection probes– ICMP– UDP– Other possible if requested
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Report
• HTML-based
• Delivered on CDROM or DVD
• Maps
• Executive summary shows highpoints
• Interactive map viewer tool for Windows
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Competitors?
• Not yet, not quite– Many use the same terms, but offer
different services
• Some components are pretty easy and free– Host enumeration– But we do it better (!)
• A bit like HP OpenView– OpenView doesn’t scale– Much slower
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Value
• Discovers unknown parts of the network
• Data feeds into existing tools, enhancing their value
• You can’t secure what you don’t know about
• Due diligence for intranets– Insurance?
• M&A activity
• Personnel turnover leaves legacy connections
• Business partners
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Getting a report
• Web-based
• We can send you a CD-ROM
• You can access a web server– FreeBSD-based– One-time password authentication– Very paranoid server
120 slides
Sample report
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Internet report
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Intranet “Best current practices”
We are acquiring the data to produce a paper: statistics over a
variety of large intranets
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Some intranet statisticsfrom Lumeta clients
Intranet sizes (devices) 7,900 365,000Corporate address space 81,000 745,000,000Address space usage efficiency% devices in unknown address space 0.01% 20.86%
% routers responding to "public" 0.14% 75.50%% routers responding to other 0.00% 52.00%
Outbound host leaks on network 0 176,000% devices with outbound ICMP leaks 0% 79%% devices with outbound UDP leaks 0% 82%
Inbound UDP host leaks 0 5,800% devices with inbound ICMP leaks 0% 11%% devices with inbound UDP leaks 0% 12%
% hosts running Windows 36% 84%
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120 slides
Mapping the Internet and
Intranets
Steve Branigan, Hal Burch, Bill Cheswick
ches@lumeta.com
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