Diagrama de secuencia de Tráfico de Red

#+LINK_HOME:   index.html

#+INCLUDE:     header.org

# no entiendo nada

Muchas veces tengo que analizar tráfico de red ¹, mayormente usando tcpdump, pero resulta que a veces es un tanto difícil entender la conversación, muchas idas y vueltas, paquetes que van y que vienen, diferentes protocolos, muchos hosts dialogando.

# graficar para entender

Para clarificar un poco qué esta sucediendo se me ocurrió graficarlo! Es decir, si guardo el tráfico de red en un archivo .pcap y después veo de filtrar ese tráfico y generar un archivo .uml con un resumen de qué le dice un host a otro host, tal vez al convertirlo en un bonito .png pueda entender mejor que esta sucendiendo!

# `pcap2uml`

Como gran parte de "mis soluciones", pcap2uml ² no es mas que un script bash que lee un .pcap utilizando tshark (la versión tty de whireshark) y luego se filtra el tráfico por protocolo y se obtiene esencialmente esto:


src_host -> dst_host : [proto] request message
dst_host -> src_host : [proto] response message

# un `.pcap` al desnudo

Si vemos un ejemplo de login LDAP + Kerberos apriori no es muy grata la salida de tcpdump

 1
 2tcpdump -nntt -r ldap-krb5-sign-seal-01.cap 
 3
 4    reading from file ldap-krb5-sign-seal-01.cap, link-type EN10MB (Ethernet)
 5    1103541634.053138 IP 172.31.1.104.3116 > 172.31.1.101.389: Flags [S], seq 2507797749, win 64240, options [mss 1460,nop,nop,sackOK], length 0
 6    1103541634.053546 IP 172.31.1.101.389 > 172.31.1.104.3116: Flags [S.], seq 2116938212, ack 2507797750, win 64240, options [mss 1460,nop,nop,sackOK], length 0
 7    1103541634.055718 IP 172.31.1.104.3116 > 172.31.1.101.389: Flags [.], ack 1, win 64240, length 0
 8    1103541634.058384 IP 172.31.1.104.3116 > 172.31.1.101.389: Flags [P.], seq 1:352, ack 1, win 64240, length 351
 9    1103541634.059344 IP 172.31.1.101.389 > 172.31.1.104.3116: Flags [.], seq 1:1461, ack 352, win 63889, length 1460
10    1103541634.059463 IP 172.31.1.101.389 > 172.31.1.104.3116: Flags [P.], seq 1461:2201, ack 352, win 63889, length 740
11    1103541634.061931 IP 172.31.1.104.3116 > 172.31.1.101.389: Flags [.], ack 2201, win 64240, length 0
12    1103541634.739853 IP 172.31.1.104.3118 > 172.31.1.101.88: 
13    1103541634.763602 IP 172.31.1.101.88 > 172.31.1.104.3118: 
14    1103541634.769640 IP 172.31.1.104.3116 > 172.31.1.101.389: Flags [P.], seq 352:1713, ack 2201, win 64240, length 1361
15    1103541634.784940 IP 172.31.1.101.389 > 172.31.1.104.3116: Flags [P.], seq 2201:2392, ack 1713, win 64240, length 191
16    1103541634.866413 IP 172.31.1.104.3116 > 172.31.1.101.389: Flags [P.], seq 1713:1815, ack 2392, win 64049, length 102
17    1103541634.867502 IP 172.31.1.101.389 > 172.31.1.104.3116: Flags [.], seq 2392:3852, ack 1815, win 64138, length 1460
18    1103541634.867613 IP 172.31.1.101.389 > 172.31.1.104.3116: Flags [P.], seq 3852:4921, ack 1815, win 64138, length 1069
19    1103541634.868121 IP 172.31.1.104.3116 > 172.31.1.101.389: Flags [.], ack 4921, win 64240, length 0
20    1103541634.869334 IP 172.31.1.104.3116 > 172.31.1.101.389: Flags [P.], seq 1815:1962, ack 4921, win 64240, length 147
21    1103541634.870170 IP 172.31.1.101.389 > 172.31.1.104.3116: Flags [P.], seq 4921:5099, ack 1962, win 63991, length 178
22    1103541634.870988 IP 172.31.1.104.3116 > 172.31.1.101.389: Flags [P.], seq 1962:2125, ack 5099, win 64062, length 163
23    1103541634.871494 IP 172.31.1.101.389 > 172.31.1.104.3116: Flags [P.], seq 5099:5954, ack 2125, win 63828, length 855
24    1103541634.872270 IP 172.31.1.104.3116 > 172.31.1.101.389: Flags [P.], seq 2125:2306, ack 5954, win 63207, length 181
25    1103541634.916866 IP 172.31.1.101.389 > 172.31.1.104.3116: Flags [.], seq 5954:7414, ack 2306, win 63647, length 1460
26    1103541634.916980 IP 172.31.1.101.389 > 172.31.1.104.3116: Flags [.], seq 7414:8874, ack 2306, win 63647, length 1460
27    1103541634.917056 IP 172.31.1.101.389 > 172.31.1.104.3116: Flags [.], seq 8874:10334, ack 2306, win 63647, length 1460
28    1103541634.917130 IP 172.31.1.101.389 > 172.31.1.104.3116: Flags [P.], seq 10334:11402, ack 2306, win 63647, length 1068
29    1103541634.918271 IP 172.31.1.104.3116 > 172.31.1.101.389: Flags [.], ack 11402, win 64240, length 0
30    1103541634.924121 IP 172.31.1.104.3116 > 172.31.1.101.389: Flags [P.], seq 2306:2484, ack 11402, win 64240, length 178
31    1103541634.925141 IP 172.31.1.101.389 > 172.31.1.104.3116: Flags [P.], seq 11402:11611, ack 2484, win 63469, length 209
32    1103541634.925920 IP 172.31.1.104.3116 > 172.31.1.101.389: Flags [P.], seq 2484:2696, ack 11611, win 64031, length 212
33    1103541634.926713 IP 172.31.1.101.389 > 172.31.1.104.3116: Flags [P.], seq 11611:12862, ack 2696, win 63257, length 1251
34    1103541634.927886 IP 172.31.1.104.3116 > 172.31.1.101.389: Flags [P.], seq 2696:2870, ack 12862, win 64240, length 174
35    1103541634.928513 IP 172.31.1.101.389 > 172.31.1.104.3116: Flags [P.], seq 12862:13053, ack 2870, win 63083, length 191
36    1103541634.929220 IP 172.31.1.104.3116 > 172.31.1.101.389: Flags [P.], seq 2870:3078, ack 13053, win 64049, length 208
37    1103541634.930274 IP 172.31.1.101.389 > 172.31.1.104.3116: Flags [.], seq 13053:14513, ack 3078, win 62875, length 1460
38    1103541634.930401 IP 172.31.1.101.389 > 172.31.1.104.3116: Flags [P.], seq 14513:15898, ack 3078, win 62875, length 1385
39    1103541634.930706 IP 172.31.1.104.3116 > 172.31.1.101.389: Flags [.], ack 15898, win 64240, length 0
40    1103541634.931883 IP 172.31.1.104.3116 > 172.31.1.101.389: Flags [P.], seq 3078:3242, ack 15898, win 64240, length 164
41    1103541634.932577 IP 172.31.1.101.389 > 172.31.1.104.3116: Flags [P.], seq 15898:16089, ack 3242, win 64240, length 191
42    1103541634.933296 IP 172.31.1.104.3116 > 172.31.1.101.389: Flags [P.], seq 3242:3406, ack 16089, win 64049, length 164
43    1103541634.933949 IP 172.31.1.101.389 > 172.31.1.104.3116: Flags [P.], seq 16089:16280, ack 3406, win 64076, length 191
44    1103541635.046572 IP 172.31.1.104.3116 > 172.31.1.101.389: Flags [.], ack 16280, win 63858, length 0
45

# un `.uml` se entiende un poco mas (o casi)

Si tomamos esa misma captura y usamos pcap2uml la salida ya aporta cierta laridad a la conversación:


title ldap-krb5-sign-seal-01.cap

hide footbox
participant "172.31.1.101" #a4c400
participant "172.31.1.104" #60a917

172.31.1.104 -[#60a917]> 172.31.1.101 : [LDAP] searchRequest 213  ROOT  baseObject
172.31.1.101 -[#a4c400]> 172.31.1.104 : [LDAP] searchResEntry 213  ROOT  | searchResDone 213 success  1 result 
172.31.1.104 -[#60a917]> 172.31.1.101 : [KRB5] TGS-REQ
172.31.1.101 -[#a4c400]> 172.31.1.104 : [KRB5] TGS-REP
172.31.1.104 -[#60a917]> 172.31.1.101 : [LDAP] bindRequest 215  ROOT  sasl
172.31.1.101 -[#a4c400]> 172.31.1.104 : [LDAP] bindResponse 215 success
172.31.1.104 -[#60a917]> 172.31.1.101 : [LDAP] SASL GSS-API Integrity 
172.31.1.101 -[#a4c400]> 172.31.1.104 : [LDAP] SASL GSS-API Integrity 
172.31.1.104 -[#60a917]> 172.31.1.101 : [LDAP] SASL GSS-API Integrity 
172.31.1.101 -[#a4c400]> 172.31.1.104 : [LDAP] SASL GSS-API Integrity 
172.31.1.104 -[#60a917]> 172.31.1.101 : [LDAP] SASL GSS-API Integrity 
172.31.1.101 -[#a4c400]> 172.31.1.104 : [LDAP] SASL GSS-API Integrity 
172.31.1.104 -[#60a917]> 172.31.1.101 : [LDAP] SASL GSS-API Integrity 
172.31.1.101 -[#a4c400]> 172.31.1.104 : [LDAP] SASL GSS-API Integrity 
172.31.1.104 -[#60a917]> 172.31.1.101 : [LDAP] SASL GSS-API Integrity 
172.31.1.101 -[#a4c400]> 172.31.1.104 : [LDAP] SASL GSS-API Integrity 
172.31.1.104 -[#60a917]> 172.31.1.101 : [LDAP] SASL GSS-API Integrity 
172.31.1.101 -[#a4c400]> 172.31.1.104 : [LDAP] SASL GSS-API Integrity 
172.31.1.104 -[#60a917]> 172.31.1.101 : [LDAP] SASL GSS-API Integrity 
172.31.1.101 -[#a4c400]> 172.31.1.104 : [LDAP] SASL GSS-API Integrity 
172.31.1.104 -[#60a917]> 172.31.1.101 : [LDAP] SASL GSS-API Integrity 
172.31.1.101 -[#a4c400]> 172.31.1.104 : [LDAP] SASL GSS-API Integrity 
172.31.1.104 -[#60a917]> 172.31.1.101 : [LDAP] SASL GSS-API Integrity 
172.31.1.101 -[#a4c400]> 172.31.1.104 : [LDAP] SASL GSS-API Integrity 
172.31.1.104 -[#60a917]> 172.31.1.101 : [LDAP] SASL GSS-API Integrity 
172.31.1.101 -[#a4c400]> 172.31.1.104 : [LDAP] SASL GSS-API Integrity

# ahora si se puede ver!

Utilizando plantuml ³ se puede convertir ese .uml en un bonito .png e incluso de ser muuuucho tráfico y muy grande la imagen resultante, se puede imprimir a lo grande y analizarla lejos del teclado.

# ChangeLog

2022-11-13 20:39 agregar y actualizar tags OpenGraph
2021-03-04 23:20 agregar Diagrama de Secuencia de Tráfico de Red usando pcap2uml