Packet capture of an iPhone 4 Facetime call

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This blog article is based on the blog article that was written by FryGuy.

This article will explain what is happening on the low level when a Facetime call is made between 2 x iPhone 4 devices.

FryGuy tested facetime and enabled packet capturing in his ASA to see what is actually happening on the network when you make a simple facetime call.

ASA packet capturing is explained HERE.

iPhone 4 #1 = IP Private – 192.168.0.128

iPhone 4 #1 = IP NAT – 216.164.100.100 iPhone 4 #2 = IP Private 192.168.2.106

iPhone 4 #2 = IP NAT – 72.81.200.200

Apple Video Servers = 17.155.5.251 / 17.155.5.252 / 17.155.4.14 Note: NATs change to protect the guilty

1.  The call is first initiated via regular Celluar networks.  In the contact list you will see an icon called FaceTime.

facetime.png

2.  The phones then communicate to a server at Apple (17.155.5.251 is what he saw).  Communication is sourced from port 16402 via UDP initially and then looks to dynamically allocate ports for communication (16385 and 16386 are what appeared on his end). 

1 0.000000 192.168.0.128 17.155.5.251 UDP Source port: 16402 Destination port: connected
2 0.431054 17.155.5.251 192.168.0.128 UDP Source port: connected Destination port: 16402
3 0.715713 192.168.0.128 17.155.5.251 UDP Source port: 51136 Destination port: connected
4 0.716064 192.168.0.128 17.155.5.251 UDP Source port: 51136 Destination port: 16385
5 0.717147 192.168.0.128 17.155.5.252 UDP Source port: 51136 Destination port: 16386
6 0.958285 17.155.5.252 192.168.0.128 UDP Source port: 16386 Destination port: 51136
7 0.960329 17.155.5.251 192.168.0.128 UDP Source port: 16385 Destination port: 51136
8 0.960588 17.155.5.251 192.168.0.128 UDP Source port: connected Destination port: 51136
9 1.016402 192.168.0.128 216.164.100.100 UDP Source port: 51136 Destination port: 52585
10 1.018172 192.168.0.128 216.164.100.100 UDP Source port: 51136 Destination port: 52585

3. The phone then negotiates an HTTPS connection to the servers at Apple for the setup and communication. There also seems to be some communication to other servers (in this case  RCN 208.59.216.10) – and they are FryGuys cable provider. 

11 1.019912 192.168.0.128 17.155.4.14 TCP 50697 > https [SYN] Seq=0 Win=65535 Len=0 MSS=1460 WS=2 TSV=469580285 TSER=0
12 1.020140 192.168.0.128 216.164.100.100 UDP Source port: 51136 Destination port: 52585
13 1.298294 17.155.4.14 192.168.0.128 TCP https > 50697 [SYN, ACK] Seq=0 Ack=1 Win=8190 Len=0 MSS=1360 WS=4
14 1.318312 192.168.0.128 17.155.4.14 TCP 50697 > https [ACK] Seq=1 Ack=1 Win=131920 Len=0
15 1.321211 192.168.0.128 17.155.4.14 TLSv1 Client Hello
16 1.645657 192.168.0.128 17.155.5.251 UDP Source port: 51136 Destination port: connected
17 1.645978 192.168.0.128 17.155.5.251 UDP Source port: 51136 Destination port: 16385
18 1.646130 192.168.0.128 17.155.5.252 UDP Source port: 51136 Destination port: 16386
19 1.662234 192.168.0.128 208.59.216.10 TCP 50698 > http [SYN] Seq=0 Win=65535 Len=0 MSS=1460 WS=2 TSV=469580291 TSER=0
20 1.730834 17.155.4.14 192.168.0.128 TCP [TCP segment of a reassembled PDU]
21 1.731963 17.155.4.14 192.168.0.128 TLSv1 Server Hello, Certificate, Server Hello Done
22 1.808298 208.59.216.10 192.168.0.128 TCP http > 50698 [SYN, ACK] Seq=0 Ack=1 Win=5792 Len=0 MSS=1380 TSV=941715237 TSER=469580291 WS=1
23 1.832208 192.168.0.128 17.155.4.14 TCP 50697 > https [ACK] Seq=160 Ack=1361 Win=130560 Len=0
24 1.834588 192.168.0.128 17.155.4.14 TCP 50697 > https [ACK] Seq=160 Ack=2490 Win=130788 Len=0
25 1.834954 192.168.0.128 208.59.216.10 TCP 50698 > http [ACK] Seq=1 Ack=1 Win=131328 Len=0 TSV=469580293 TSER=941715237
26 1.836526 192.168.0.128 208.59.216.10 HTTP GET /WebObjects/VCInit.woa/wa/getBag?ix=1 HTTP/1.1
27 1.881018 17.155.5.252 192.168.0.128 UDP Source port: 16386 Destination port: 51136
28 1.882147 17.155.5.251 192.168.0.128 UDP Source port: connected Destination port: 51136
29 1.883124 17.155.5.251 192.168.0.128 UDP Source port: 16385 Destination port: 51136
30 1.884207 192.168.0.128 216.164.100.100 UDP Source port: 51136 Destination port: 52585
31 1.886053 192.168.0.128 216.164.100.100 UDP Source port: 51136 Destination port: 52585
32 1.886343 192.168.0.128 216.164.100.100 UDP Source port: 51136 Destination port: 52585
33 1.930729 192.168.0.128 17.155.4.14 TLSv1 Client Key Exchange
34 1.930835 192.168.0.128 17.155.4.14 TLSv1 Change Cipher Spec
35 1.931583 192.168.0.128 17.155.4.14 TLSv1 Encrypted Handshake Message
36 2.190008 208.59.216.10 192.168.0.128 TCP http > 50698 [ACK] Seq=1 Ack=229 Win=6432 Len=0 TSV=941715619 TSER=469580293
37 2.190313 208.59.216.10 192.168.0.128 TCP [TCP segment of a reassembled PDU]
38 2.191366 208.59.216.10 192.168.0.128 TCP [TCP segment of a reassembled PDU]
39 2.192312 208.59.216.10 192.168.0.128 HTTP/XML HTTP/1.1 200 OK
40 2.242678 192.168.0.128 208.59.216.10 TCP 50698 > http [ACK] Seq=229 Ack=2737 Win=128592 Len=0 TSV=469580297 TSER=941715619
41 2.243014 192.168.0.128 208.59.216.10 TCP 50698 > http [ACK] Seq=229 Ack=3506 Win=127820 Len=0 TSV=469580297 TSER=941715619
42 2.393275 17.155.4.14 192.168.0.128 TCP https > 50697 [ACK] Seq=2490 Ack=299 Win=35216 Len=0
43 2.393305 17.155.4.14 192.168.0.128 TCP https > 50697 [ACK] Seq=2490 Ack=305 Win=35216 Len=0
44 2.393351 17.155.4.14 192.168.0.128 TCP https > 50697 [ACK] Seq=2490 Ack=342 Win=35184 Len=0
45 2.394633 17.155.4.14 192.168.0.128 TLSv1 Change Cipher Spec, Encrypted Handshake Message
46 2.448112 192.168.0.128 17.155.4.14 TCP 50697 > https [ACK] Seq=342 Ack=2533 Win=131876 Len=0
47 2.449760 192.168.0.128 17.155.4.14 TLSv1 Application Data
48 2.450325 192.168.0.128 17.155.4.14 TLSv1 Application Data
49 2.511448 192.168.0.128 17.155.5.251 UDP Source port: 51136 Destination port: connected
50 2.512608 192.168.0.128 17.155.5.251 UDP Source port: 51136 Destination port: 16385
51 2.512776 192.168.0.128 17.155.5.252 UDP Source port: 51136 Destination port: 16386
52 2.905644 17.155.5.252 192.168.0.128 UDP Source port: 16386 Destination port: 51136
53 2.905690 17.155.4.14 192.168.0.128 TCP https > 50697 [ACK] Seq=2533 Ack=966 Win=34560 Len=0
54 2.905782 17.155.4.14 192.168.0.128 TCP https > 50697 [ACK] Seq=2533 Ack=1453 Win=34064 Len=0
55 2.906896 17.155.5.251 192.168.0.128 UDP Source port: 16385 Destination port: 51136
56 2.907536 17.155.5.251 192.168.0.128 UDP Source port: connected Destination port: 51136
57 2.923466 17.155.4.14 192.168.0.128 TLSv1 Application Data
58 2.923924 17.155.4.14 192.168.0.128 TLSv1 Application Data
59 3.060254 192.168.0.128 216.164.100.100 UDP Source port: 51136 Destination port: 52585
60 3.060422 192.168.0.128 216.164.100.100 UDP Source port: 51136 Destination port: 52585
61 3.062146 192.168.0.128 17.155.4.14 TCP 50697 > https [ACK] Seq=1453 Ack=2894 Win=131556 Len=0
62 3.062451 192.168.0.128 17.155.4.14 TCP 50697 > https [ACK] Seq=1453 Ack=3240 Win=131212 Len=0
63 3.062741 192.168.0.128 199.7.52.190 TCP 50699 > http [SYN] Seq=0 Win=65535 Len=0 MSS=1460 WS=2 TSV=469580305 TSER=0
64 3.063122 192.168.0.128 216.164.100.100 UDP Source port: 51136 Destination port: 52585
65 3.532458 199.7.52.190 192.168.0.128 TCP http > 50699 [SYN, ACK] Seq=0 Ack=1 Win=8190 Len=0 MSS=1380
66 3.571122 192.168.0.128 199.7.52.190 TCP 50699 > http [ACK] Seq=1 Ack=1 Win=65535 Len=0
67 3.579117 192.168.0.128 199.7.52.190 HTTP GET /EVIntl2006.cer HTTP/1.1
68 3.690690 192.168.0.128 17.155.4.14 TLSv1 Encrypted Alert
69 3.692505 192.168.0.128 17.155.5.251 UDP Source port: 51136 Destination port: connected
70 3.696701 192.168.0.128 17.155.4.14 TCP 50697 > https [FIN, ACK] Seq=1476 Ack=3240 Win=131920 Len=0
71 3.697007 192.168.0.128 208.59.216.10 TCP 50698 > http [FIN, ACK] Seq=229 Ack=3506 Win=131328 Len=0 TSV=469580312 TSER=941715619
72 3.697388 192.168.0.128 17.155.5.251 UDP Source port: 51136 Destination port: 16385
73 3.697617 192.168.0.128 17.155.5.252 UDP Source port: 51136 Destination port: 16386
74 3.809626 199.7.52.190 192.168.0.128 TCP [TCP segment of a reassembled PDU]
75 3.810572 199.7.52.190 192.168.0.128 HTTP HTTP/1.0 200 OK (text/plain)
76 3.881720 192.168.0.128 199.7.52.190 TCP 50699 > http [ACK] Seq=154 Ack=1865 Win=65535 Len=0
77 3.890585 192.168.0.128 199.7.52.190 TCP 50699 > http [FIN, ACK] Seq=154 Ack=1865 Win=65535 Len=0
78 3.952258 208.59.216.10 192.168.0.128 TCP http > 50698 [FIN, ACK] Seq=3506 Ack=230 Win=6432 Len=0 TSV=941717381 TSER=469580312
79 3.954256 192.168.0.128 208.59.216.10 TCP 50698 > http [ACK] Seq=230 Ack=3507 Win=131328 Len=0 TSV=469580314 TSER=941717381
80 4.007781 17.155.4.14 192.168.0.128 TCP https > 50697 [ACK] Seq=3240 Ack=1476 Win=40928 Len=0
81 4.007965 17.155.4.14 192.168.0.128 TCP https > 50697 [FIN, ACK] Seq=3240 Ack=1477 Win=40928 Len=0
82 4.009155 17.155.5.251 192.168.0.128 UDP Source port: 16385 Destination port: 51136
83 4.009170 17.155.5.251 192.168.0.128 UDP Source port: connected Destination port: 51136
84 4.009948 192.168.0.128 17.155.4.14 TCP 50697 > https [FIN, ACK] Seq=1476 Ack=3240 Win=131920 Len=0
85 4.014495 192.168.0.128 17.155.4.14 TCP 50697 > https [ACK] Seq=1477 Ack=3241 Win=131920 Len=0
86 4.019866 192.168.0.128 216.164.100.100 UDP Source port: 51136 Destination port: 52585
87 4.023955 17.155.5.252 192.168.0.128 UDP Source port: 16386 Destination port: 51136
88 4.025984 192.168.0.128 216.164.100.100 UDP Source port: 51136 Destination port: 52585
89 4.034971 192.168.0.128 216.164.100.100 UDP Source port: 51136 Destination port: 52585
90 4.504292 199.7.52.190 192.168.0.128 TCP http > 50699 [ACK] Seq=1865 Ack=155 Win=8190 Len=0
91 4.671800 192.168.0.128 17.155.5.251 UDP Source port: 51136 Destination port: connected
92 4.672167 192.168.0.128 17.155.5.251 UDP Source port: 51136 Destination port: 16385
93 4.672411 192.168.0.128 17.155.5.252 UDP Source port: 51136 Destination port: 16386
94 5.139092 17.155.5.252 192.168.0.128 UDP Source port: 16386 Destination port: 51136
95 5.140068 17.155.5.251 192.168.0.128 UDP Source port: 16385 Destination port: 51136
96 5.140129 17.155.5.251 192.168.0.128 UDP Source port: connected Destination port: 51136
97 5.210011 192.168.0.128 216.164.100.100 UDP Source port: 51136 Destination port: 52585
98 5.215809 192.168.0.128 216.164.100.100 UDP Source port: 51136 Destination port: 52585
99 5.216068 192.168.0.128 216.164.100.100 UDP Source port: 51136 Destination port: 52585
100 5.715774 192.168.0.128 17.155.5.251 UDP Source port: 51136 Destination port: 16385
101 6.054578 17.155.5.251 192.168.0.128 UDP Source port: 16385 Destination port: 51136

4. After Client (iPhone) and server negotiation you start to see Stun requests via the private IPs, after they fail you see them from the Public IP NAT ranges. They success via the Public peering at that point. 

102 8.258196 192.168.0.128 192.168.2.106 STUN2 Binding Request
103 8.286606 192.168.0.128 192.168.2.106 STUN2 Binding Request
104 8.303893 192.168.0.128 72.81.200.200 STUN2 Binding Request
105 8.313353 192.168.0.128 192.168.2.106 STUN2 Binding Request
106 8.313582 72.81.200.200 192.168.0.128 STUN2 Binding Request
107 8.316909 192.168.0.128 72.81.200.200 STUN2 Binding Success Response
108 8.333677 192.168.0.128 72.81.200.200 STUN2 Binding Request
109 8.344419 72.81.200.200 192.168.0.128 STUN2 Binding Request
110 8.350980 192.168.0.128 72.81.200.200 STUN2 Binding Success Response
111 8.360852 192.168.0.128 72.81.200.200 STUN2 Binding Request
112 8.374294 72.81.200.200 192.168.0.128 STUN2 Binding Request
113 8.376750 192.168.0.128 72.81.200.200 STUN2 Binding Success Response
114 8.467002 192.168.0.128 192.168.2.106 STUN2 Binding Request
115 8.496083 192.168.0.128 192.168.2.106 STUN2 Binding Request
116 8.528156 72.81.200.200 192.168.0.128 STUN2 Binding Request
117 8.530139 192.168.0.128 72.81.200.200 STUN2 Binding Request
118 8.530765 192.168.0.128 72.81.200.200 STUN2 Binding Success Response
119 8.553316 72.81.200.200 192.168.0.128 STUN2 Binding Request
120 8.555467 192.168.0.128 72.81.200.200 STUN2 Binding Request
121 8.556032 192.168.0.128 72.81.200.200 STUN2 Binding Success Response
122 8.626234 72.81.200.200 192.168.0.128 STUN2 Binding Success Response
123 8.629896 72.81.200.200 192.168.0.128 STUN2 Binding Success Response

5. A SIP call is then initiated between the phones for the video portion of the call 

124 8.730361 192.168.0.128 72.81.200.200 SIP/SDP Request: INVITE sip:user@72.81.200.200:50925, with session description
125 8.748746 72.81.200.200 192.168.0.128 STUN2 Binding Success Response
126 8.771618 192.168.0.128 192.168.2.106 STUN2 Binding Request
127 8.797557 192.168.0.128 192.168.2.106 STUN2 Binding Request
128 8.925571 72.81.200.200 192.168.0.128 STUN2 Binding Success Response
129 8.927723 72.81.200.200 192.168.0.128 STUN2 Binding Success Response
130 9.232700 192.168.0.128 72.81.200.200 SIP/SDP Request: INVITE sip:user@72.81.200.200:50925, with session description
131 9.258562 192.168.0.128 192.168.2.106 STUN2 Binding Request
132 9.262926 72.81.200.200 192.168.0.128 SIP Status: 100 Trying
133 9.268831 72.81.200.200 192.168.0.128 SIP Status: 180 Ringing
134 9.296692 192.168.0.128 192.168.2.106 STUN2 Binding Request
135 9.320586 72.81.200.200 192.168.0.128 SIP/SDP Status: 200 OK, with session description
136 9.326857 192.168.0.128 72.81.200.200 SIP Request: ACK sip:user@72.81.200.200:50925
137 9.334699 192.168.0.128 72.81.200.200 SIP Request: MESSAGE sip:user@72.81.200.200:50925
138 9.688477 72.81.200.200 192.168.0.128 SIP/SDP Status: 200 OK, with session description
139 9.716567 192.168.0.128 72.81.200.200 SIP Request: ACK sip:user@72.81.200.200:50925
140 9.834542 192.168.0.128 72.81.200.200 SIP Request: MESSAGE sip:user@72.81.200.200:50925
141 10.216053 72.81.200.200 192.168.0.128 SIP Status: 200 OK
142 10.230152 192.168.0.128 72.81.200.200 SIP Request: MESSAGE sip:user@72.81.200.200:50925
143 10.442848 72.81.200.200 192.168.0.128 SIP Status: 200 OK
144 10.491689 72.81.200.200 192.168.0.128 SIP Status: 200 OK
145 10.727812 192.168.0.128 72.81.200.200 SIP Request: MESSAGE sip:user@72.81.200.200:50925
146 11.229984 192.168.0.128 72.81.200.200 SIP Request: MESSAGE sip:user@72.81.200.200:50925
147 11.318007 72.81.200.200 192.168.0.128 SIP Status: 200 OK
148 11.367565 192.168.0.128 72.81.200.200 SIP Request: MESSAGE sip:user@72.81.200.200:50925
149 11.618986 72.81.200.200 192.168.0.128 SIP Status: 200 OK
150 11.866691 192.168.0.128 72.81.200.200 SIP Request: MESSAGE sip:user@72.81.200.200:50925
151 11.998932 192.168.0.128 72.81.200.200 UDP Source port: 16402 Destination port: 50925
152 12.035444 72.81.200.200 192.168.0.128 SIP Status: 200 OK
153 12.063916 192.168.0.128 72.81.200.200 UDP Source port: 16402 Destination port: 50925
154 12.129174 192.168.0.128 72.81.200.200 UDP Source port: 16402 Destination port: 50925
155 12.180258 192.168.0.128 72.81.200.200 UDP Source port: 16402 Destination port: 50925
156 12.183416 192.168.0.128 72.81.200.200 UDP Source port: 16402 Destination port: 50925
157 12.187093 72.81.200.200 192.168.0.128 SIP Status: 200 OK
158 12.195043 192.168.0.128 72.81.200.200 UDP Source port: 16402 Destination port: 50925
159 12.200932 72.81.200.200 192.168.0.128 SIP Request: BYE sip:user@192.168.0.128:16402
160 12.206181 192.168.0.128 72.81.200.200 SIP Status: 200 OK

6. So in the end, this is a Video SIP call

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