Re: Une trace réseau ?

Donc me revoici avec un tcpdump host xx.xx.xx.xx -w nomfich.pcap (pour ouverture sur Wireshark) effectué sur le serveur FTP.

Client 1 (tout fonctionne bien) :
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No. Time Source Destination Protocol Info
25 36.586701 yy.yy.yy.yy xx.xx.xx.xx FTP Response: 227 Entering Passive Mode (yy,yy,yy,yy,2

Frame 25 (105 bytes on wire, 96 bytes captured)
Internet Protocol, Src: yy.yy.yy.yy (yy.yy.yy.yy), Dst: xx.xx.xx.xx (xx.xx.xx.xx)
Transmission Control Protocol, Src Port: ftp (21), Dst Port: must-backplane (3515), Seq: 222, Ack: 65, Len: 51
File Transfer Protocol (FTP)

No. Time Source Destination Protocol Info
26 36.642267 xx.xx.xx.xx yy.yy.yy.yy TCP smartcard-port > 54318 [SYN] Seq=0 Win=65535 Len=0 MSS=1422 WS=3 TSV=0 TSER=0

Frame 26 (78 bytes on wire, 78 bytes captured)
Internet Protocol, Src: xx.xx.xx.xx (xx.xx.xx.xx), Dst: yy.yy.yy.yy (yy.yy.yy.yy)
Transmission Control Protocol, Src Port: smartcard-port (3516), Dst Port: 54318 (54318), Seq: 0, Len: 0

No. Time Source Destination Protocol Info
27 36.642287 yy.yy.yy.yy xx.xx.xx.xx TCP 54318 > smartcard-port [SYN, ACK] Seq=0 Ack=1 Win=5840 Len=0 MSS=1460 WS=2

Frame 27 (66 bytes on wire, 66 bytes captured)
Internet Protocol, Src: yy.yy.yy.yy (yy.yy.yy.yy), Dst: xx.xx.xx.xx (xx.xx.xx.xx)
Transmission Control Protocol, Src Port: 54318 (54318), Dst Port: smartcard-port (3516), Seq: 0, Ack: 1, Len: 0

No. Time Source Destination Protocol Info
28 36.642933 xx.xx.xx.xx yy.yy.yy.yy FTP Request: LIST

Frame 28 (60 bytes on wire, 60 bytes captured)
Internet Protocol, Src: xx.xx.xx.xx (xx.xx.xx.xx), Dst: yy.yy.yy.yy (yy.yy.yy.yy)
Transmission Control Protocol, Src Port: must-backplane (3515), Dst Port: ftp (21), Seq: 65, Ack: 273, Len: 6
File Transfer Protocol (FTP)

No. Time Source Destination Protocol Info
29 36.682779 yy.yy.yy.yy xx.xx.xx.xx TCP ftp > must-backplane [ACK] Seq=273 Ack=71 Win=5840 Len=0

Frame 29 (54 bytes on wire, 54 bytes captured)
Internet Protocol, Src: yy.yy.yy.yy (yy.yy.yy.yy), Dst: xx.xx.xx.xx (xx.xx.xx.xx)
Transmission Control Protocol, Src Port: ftp (21), Dst Port: must-backplane (3515), Seq: 273, Ack: 71, Len: 0

No. Time Source Destination Protocol Info
30 36.695941 xx.xx.xx.xx yy.yy.yy.yy TCP smartcard-port > 54318 [ACK] Seq=1 Ack=1 Win=372296 Len=0

Frame 30 (60 bytes on wire, 60 bytes captured)
Internet Protocol, Src: xx.xx.xx.xx (xx.xx.xx.xx), Dst: yy.yy.yy.yy (yy.yy.yy.yy)
Transmission Control Protocol, Src Port: smartcard-port (3516), Dst Port: 54318 (54318), Seq: 1, Ack: 1, Len: 0

No. Time Source Destination Protocol Info
31 36.696020 yy.yy.yy.yy xx.xx.xx.xx FTP Response: 150 Opening ASCII mode data connection for

Frame 31 (108 bytes on wire, 96 bytes captured)
Internet Protocol, Src: yy.yy.yy.yy (yy.yy.yy.yy), Dst: xx.xx.xx.xx (xx.xx.xx.xx)
Transmission Control Protocol, Src Port: ftp (21), Dst Port: must-backplane (3515), Seq: 273, Ack: 71, Len: 54
File Transfer Protocol (FTP)

No. Time Source Destination Protocol Info
32 36.697031 yy.yy.yy.yy xx.xx.xx.xx TCP 54318 > smartcard-port [PSH, ACK] Seq=1 Ack=1 Win=5840 Len=62

Frame 32 (116 bytes on wire, 96 bytes captured)
Internet Protocol, Src: yy.yy.yy.yy (yy.yy.yy.yy), Dst: xx.xx.xx.xx (xx.xx.xx.xx)
Transmission Control Protocol, Src Port: 54318 (54318), Dst Port: smartcard-port (3516), Seq: 1, Ack: 1, Len: 62
Data (42 bytes)

0000 64 72 77 78 72 77 78 72 2d 78 20 20 20 32 20 77 drwxrwxr-x 2 w
0010 77 77 64 61 74 61 20 20 77 77 77 64 61 74 61 20 wwdata wwwdata
0020 20 20 20 20 20 34 30 39 36 20 4096

No. Time Source Destination Protocol Info
33 36.697074 yy.yy.yy.yy xx.xx.xx.xx TCP 54318 > smartcard-port [FIN, ACK] Seq=63 Ack=1 Win=5840 Len=0

Frame 33 (54 bytes on wire, 54 bytes captured)
Internet Protocol, Src: yy.yy.yy.yy (yy.yy.yy.yy), Dst: xx.xx.xx.xx (xx.xx.xx.xx)
Transmission Control Protocol, Src Port: 54318 (54318), Dst Port: smartcard-port (3516), Seq: 63, Ack: 1, Len: 0

No. Time Source Destination Protocol Info
34 36.750449 xx.xx.xx.xx yy.yy.yy.yy TCP smartcard-port > 54318 [ACK] Seq=1 Ack=64 Win=372232 Len=0

Frame 34 (60 bytes on wire, 60 bytes captured)
Internet Protocol, Src: xx.xx.xx.xx (xx.xx.xx.xx), Dst: yy.yy.yy.yy (yy.yy.yy.yy)
Transmission Control Protocol, Src Port: smartcard-port (3516), Dst Port: 54318 (54318), Seq: 1, Ack: 64, Len: 0

No. Time Source Destination Protocol Info
35 36.751283 xx.xx.xx.xx yy.yy.yy.yy TCP smartcard-port > 54318 [FIN, ACK] Seq=1 Ack=64 Win=372232 Len=0
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Client 2 (problème) :
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No. Time Source Destination Protocol Info
21 1.357257 xx.xx.xx.xx yy.yy.yy.yy FTP Response: 200 Type set to A

Frame 21 (73 bytes on wire, 73 bytes captured)
Internet Protocol, Src: yy.yy.yy.yy (yy.yy.yy.yy), Dst: xx.xx.xx.xx (xx.xx.xx.xx)
Transmission Control Protocol, Src Port: ftp (21), Dst Port: serialgateway (1243), Seq: 203, Ack: 59, Len: 19
File Transfer Protocol (FTP)

No. Time Source Destination Protocol Info
22 1.512068 xx.xx.xx.xx yy.yy.yy.yy FTP Request: PASV

Frame 22 (60 bytes on wire, 60 bytes captured)
Internet Protocol, Src: xx.xx.xx.xx (xx.xx.xx.xx), Dst: yy.yy.yy.yy (yy.yy.yy.yy)
Transmission Control Protocol, Src Port: serialgateway (1243), Dst Port: ftp (21), Seq: 59, Ack: 222, Len: 6
File Transfer Protocol (FTP)

No. Time Source Destination Protocol Info
23 1.512439 yy.yy.yy.yy xx.xx.xx.xx FTP Response: 227 Entering Passive Mode (195,200,78,75,2

Frame 23 (106 bytes on wire, 96 bytes captured)
Internet Protocol, Src: yy.yy.yy.yy (yy.yy.yy.yy), Dst: xx.xx.xx.xx (xx.xx.xx.xx)
Transmission Control Protocol, Src Port: ftp (21), Dst Port: serialgateway (1243), Seq: 222, Ack: 65, Len: 52
File Transfer Protocol (FTP)

No. Time Source Destination Protocol Info
24 1.668510 xx.xx.xx.xx yy.yy.yy.yy FTP Request: LIST

Frame 24 (60 bytes on wire, 60 bytes captured)
Internet Protocol, Src: xx.xx.xx.xx (xx.xx.xx.xx), Dst: yy.yy.yy.yy (yy.yy.yy.yy)
Transmission Control Protocol, Src Port: serialgateway (1243), Dst Port: ftp (21), Seq: 65, Ack: 274, Len: 6
File Transfer Protocol (FTP)

No. Time Source Destination Protocol Info
25 1.708075 yy.yy.yy.yy xx.xx.xx.xx TCP ftp > serialgateway [ACK] Seq=274 Ack=71 Win=5840 Len=0

Frame 25 (54 bytes on wire, 54 bytes captured)
Internet Protocol, Src: yy.yy.yy.yy (yy.yy.yy.yy), Dst: xx.xx.xx.xx (xx.xx.xx.xx)
Transmission Control Protocol, Src Port: ftp (21), Dst Port: serialgateway (1243), Seq: 274, Ack: 71, Len: 0

No. Time Source Destination Protocol Info
26 53.006899 xx.xx.xx.xx yy.yy.yy.yy TCP serialgateway > ftp [RST, ACK] Seq=71 Ack=274 Win=0 Len=0

Frame 26 (60 bytes on wire, 60 bytes captured)
Internet Protocol, Src: xx.xx.xx.xx (xx.xx.xx.xx), Dst: yy.yy.yy.yy (yy.yy.yy.yy)
Transmission Control Protocol, Src Port: serialgateway (1243), Dst Port: ftp (21), Seq: 71, Ack: 274, Len: 0
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Il n'y a effectivement aucune trame échangée en dehors du port 21 côté serveur.
Après la réponse du serveur "Entering Passive Mode", le client 1 envoie la trame [SYN] sur le port indiqué (ici 54318). Pour le client 2, cette trame n'est pas envoyée.

Le port n'est donc pas ouvert en "sortie" au niveau du firewall chez le client 2 et c'est pour cette raison que la requête n'est pas envoyée au serveur ?