Zuckerman and McLaughlin : Introduction to Internet Architecture and Institutions : Class Notes

Follow the Header
(or "Around the World in 900 Milliseconds")

X-Originating-IP: [209.198.247.19]
From: "Ethan Zuckerman" yaoobruni@hotmail.com
To: mclaughlin@pobox.com
BcHotmail:
Subject: 70 hops
Date: Fri, 14 Mar 2003 13:13:31 -0500
X-OriginalArrivalTime: 14 Mar 2003 11:13:31.0535 (UTC)
FILETIME=[471B39F0:01C2D6B0] X-Loop-Detect: 1

Hey Andrew -

Checking Hotmail from my office in Accra - just got your email from Mongolia. Glad you're enjoying Ulaanbaatar. If I'm counting correctly, receiving and reading your email involved a minimum of 70 computers in 5 nations - makes you realize just how cool the net really is!

Take care,

-E

Reply-To: mclaughlin@pobox.com
From: "Andrew McLaughlin" mclaughlin@pobox.com
To: "Ethan Zuckerman" ethan@geekcorps.org
Subject: 70 hops
Date: Fri, 14 Mar 2003 08:59:23 -0500
X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2911.0)
Importance: Normal
X-Loop-Detect: 1

Ethan -

70 computers - no kidding! That translates into dozens and dozens of organizations, from Internet architects to ISPs, located in at least 20 different legal jurisdictions.

No wonder so many governments (and lawyers) think of the Internet as a headache.

--andrew

Chinngis Khan cybercafe (via Magicnet): 202.131.3.23
Andrew's laptop (via NAT & DHCP): 192.168.0.5

Path from Andrew's laptop to Berkman Center mailserver:

1 cobalt03.mn (Magicnet Mongolia) (202.131.0.79)
2 China Satnet (203.222.194.18)
3 China Satnet (203.222.192.97)
4 SATNETEX - China Digital satNet Ltd. (203.222.192.68)
5 DigitalNetworkAlliance.GW.opentransit.net (193.251.252.230)
6 P2-1-0.HKGAR1.Hong-kong.opentransit.net (193.251.241.198)
7 P2-3.HKGBB2.Hong-kong.opentransit.net (193.251.242.189)
8 P13-0.SJOCR2.San-jose.opentransit.net (193.251.242.90)
9 P4-0.SJOCR1.San-jose.opentransit.net (193.251.242.2)
10 P5-0.NYKCR2.New-york.opentransit.net (193.251.251.225)
11 P4-0.NYKCR3.New-york.opentransit.net (193.251.242.253)
12 So2-0-0.ASHBB1.Ashburn.opentransit.net (193.251.248.177)
13 dcp-brdr-01.inet.qwest.net (205.171.209.46)
14 dca-core-01.inet.qwest.net (205.171.9.9)
15 dca-core-03.inet.qwest.net (205.171.8.218)
16 jfk-core-03.inet.qwest.net (205.171.230.6)
17 jfk-core-01.inet.qwest.net (205.171.8.19)
18 bos-core-02.inet.qwest.net (205.171.28.29)
19 bos-edge-02.inet.qwest.net (63.145.1.133)
20 Harvard router (192.5.66.5)
21 border-gw-ge-wan3-1.fas.harvard.edu (140.247.2.5)
22 core-1-gw-vl415.fas.harvard.edu (140.247.2.61)
23 core-nw-gw-vl216.fas.harvard.edu (140.247.216.1)
24 cyber-mail.law.harvard.edu (140.247.216.113)

More on Traceroute

Conversation between cyber-mail.law.harvard.edu and geekcorps.org

geekcorps.org: 220 SMTP Service Ready
cyber-mail: HELO geekcorps.org
geekcorps.org: 250 OK

cyber-mail: MAIL FROM:< mclaughlin@cyber-mail.law.harvard.edu >
geekcorp.org: 250 OK
cyber-mail: RCPT TO: < ethan@geekcorps.org >
geekcorp.org: 250 OK

cyber-mail: DATA
geekcorp.org: 354 Start mail input; end with < CRLF >. < CRLF >
cyber-mail: Hi Ethan, I'm here in Ulaanbaatar... [etc.]
cyber-mail: .
geekcorp.org: 250 OK
cyber-mail: QUIT
geekcorp.org: 221 Service closing transmission channel

Path from cyber-mail.law.harvard.edu to geekcorps.org:

1 core-nw-gw-vl216.fas.harvard.edu (140.247.216.1)
2 core-1-gw-vl415.fas.harvard.edu (140.247.2.61)
3 border-gw-ge-wan3-1.fas.harvard.edu (140.247.2.5)
4 192.5.66.5 (192.5.66.5)
5 bos-edge-02.inet.qwest.net (63.145.1.133)
6 bos-core-02.inet.qwest.net (205.171.28.29)
7 jfk-core-01.inet.qwest.net (205.171.8.19)
8 jfk-core-02.inet.qwest.net (205.171.230.2)
9 ewr-core-01.inet.qwest.net (205.171.8.245)
10 ewr-core-03.inet.qwest.net (205.171.17.6)
11 ewr-brdr-01.inet.qwest.net (205.171.17.98)
12 p4-1-0-0.r01.nwrknj01.us.bb.verio.net (129.250.9.237)
13 p16-1-1-1.r21.nycmny01.us.bb.verio.net (129.250.5.13)
14 p16-1-0-1.r21.asbnva01.us.bb.verio.net (129.250.5.99)
15 p64-0-0-0.r20.asbnva01.us.bb.verio.net (129.250.2.34)
16 p16-3-0-0.r00.stngva01.us.bb.verio.net (129.250.2.74)
17 ge-1-1.r0709.stngva01.us.wh.verio.net (129.250.27.186)
18 * * *
19 www.geekcorps.org (198.65.242.91)

Conversation between Ethan's machine and Hotmail.com webserver:

GET /index.html
From: 209.198.220.120
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows 2000)

Hotmail.com webserver response:

HTTP/1.1 200 OK
Date: Fri, 14 Mar 2003 3:35:28 PDT
Content-Type: text/html
Content-Length: 1354

< html >
< title >Welcome to Hotmail! < /title >
etc...

Path from Hotmail webserver (located on the Microsoft Network) to Ethan's office in Accra, Ghana:

1. vlan701.law13-msfc-b.us.msn.net (64.4.63.12)
2. pos10-0.law7-gsr-a.us.msn.net (64.4.63.74)
3. 65.57.86.6 (Level 3 - probably router used for private peering MSN)
4. so-7-0-0.gar1.SanJose1.Level3.net (64.159.1.74)
5. so-0-0-0.mp1.SanJose1.level3.net (64.159.1.133)
6. ae0-54.mp2.NewYork1.Level3.net (64.159.17.98)
7. ae0-52.mp2.NewYork1.Level3.net (64.159.17.34)
8. ae0-56.mp2.NewYork1.Level3.net (64.159.17.162)
9. gige9-1-52.hsipaccess1.NewYork1.Level3.net (64.159.17.39)
10.gige9-0-53.hsipaccess1.NewYork1.Level3.net (64.159.17.71)
11.gige9-1-54.hsipaccess1.NewYork1.Level3.net (64.159.17.103)
12.unknown.Level3.net (209.244.160.242)
13.host-66-133-0-22.verestar.net (66.133.0.22)
14.unknown.Level3.net (64.158.116.117)
15.unknown.Level3.net (64.158.116.94)
16.ch-leuk-in4.interpacket.net (64.110.144.21)
17.host-64-110-84-218.interpacket.net (64.110.84.218)
18.www.idngh.com (209.198.247.19) (Intercom Data Network - Ghana)

Conversation between Hotmail.com and geekcorps.org:

Geekcorps: +OK POP3 server ready < geekcorps.org >
Hotmail: APOP ethan c4c9334bac560ecc979e58001b3e22fb
Geekcorps: +OK ethan's maildrop has 2 messages (320 octets)
Hotmail: STAT
Geekcorps: +OK 2 320
Hotmail: LIST
Geekcorps: +OK 2 messages (320 octets)
Geekcorps: 1 120
Geekcorps: 2 200
Geekcorps: .
Hotmail: RETR 1
Geekcorps: +OK 120 octets
Geekcorps: (the first message)
Geekcorps: .
Hotmail: DELE 1
Geekcorps: +OK message 1 deleted
Hotmail: RETR 2
Geekcorps: +OK 200 octets
Geekcorps: (the second message)
Geekcorps: .
Hotmail: DELE 2
Geekcorps: +OK message 2 deleted
Hotmail: QUIT
Geekcorps: +OK hotmail POP3 server signing off (maildrop empty)

Path from geekcorps.org to hotmail.com:

1. www.geekcorps.org (198.65.242.91)
2. ge-25-a0725.stngva01.us.verio.net (192.67.242.125) Verio, Sterling, VA
3. ge-1-1.r0709.stngva01.us.wh.verio.net (129.250.27.186) Verio webhosting, Sterling, VA
4. p16-3-0-0.r00.stngva01.us.bb.verio.net (129.250.2.74) Verio backbone, Sterling, VA
5. blah.blah.dnvrco01.us.bb.verio.net (123.45.67.89) Verio backbone, Denver, CO
6. p4-1-2-0.r00.snjsca04.us.bb.verio.net (129.250.4.31) Verio backbone, San Jose, CA
7. p16-0-1-0.r21.snjsca04.us.bb.verio.net (129.250.5.137)
8. p16-1-1-2.r21.plalca01.us.bb.verio.net (129.250.2.198) Verio backbone, Palo Alto, CA
9. p16-1-0-0.r00.plalca01.us.bb.verio.net (129.250.3.85)
10. 198.32.176.152 (198.32.176.152) Pacific Bell network exchange point, Marina Del Rey, CA
11. pos0-0.core1.pao1.us.msn.net (207.46.33.45) MSN, Palo Alto, CA
12. pos6-1.paix-osr-a.us.msn.net (207.46.37.2)
13. pos12-0.law2-gsr-a.us.msn.net (64.4.63.58)
14. gig6-0-0.law5-rsp-b.us.msn.net (216.32.183.13)
15. hotmail.com (64.4.43.7)

DNS = Domain Name System

To get email to ethan@geekcorps.org, Andrew's laptop needs to find IP address of Ethan's mailserver (geekcorps.org)
geekcorps.org = 198.65.242.91

DNS

Deployed in the late 1980s
Highly distributed Internet directory service that allows the use of easy-to-remember domain names instead of numerical IP addresses.
The DNS naming hierarchy is organized into "domains"
- 258 top-level domains: .com, .net., .gov, .info, .jp, .ca, .cn, .mn, .gh
- 15 are generic strings with three or more letters
- 243 are country- or territory-specific two-letter strings.

Distributed system

Authority is spread far and wide through
Users can change IP addresses (i.e., network locations) anytime
Users can provide
Concept of "zones"
- Example: cyber.law.harvard.edu

13 DNS root nameservers

DNS Root Zone File

How Andrew's laptop resolves the IP address for Ethan's mailserver:

Laptop queries local DNS nameservers (assigned by cybercafe via DHCP)
If not cached, local DNS nameserver queries DNS Root Server M, in Tokyo, asking for .org nameserver
M responds with list of .org nameserver (tld1.ultradns.net, at IP address 204.74.112.1)
Local DNS nameserver queries tld1.ultradns.net, asking for geekcorps.org nameserver
tld1.ultradns.net responds with nameservers for geekcorps.org (ns11a.verio-web.com, at IP address 161.58.148.38)
Local DNS nameserver queries ns11a.verio-web.com, asking for geekcorps.org IP address
ns11a.verio-web.com responds with 198.65.242.91

Including DNS, number of machines involved in Ethan and Andrew's simple exchange of email:

Over 100 computers in 6 countries.

This work is licensed under a Creative Commons License.