Recently, I noticed traffic from the office network to TCP port 445 on the Internet [a]. Below are the Linux firewall log entries to Facebook's network [b] and Google's network [c]. I would like to identify the source of this traffic. My first guess is that Facebook and Google might be using multiple TCP ports for SSL load balancing. However, I could not confirm this based on the web proxy logs. What else might it be?

[a] http://support.microsoft.com/kb/204279

[b] Sep 4 08:30:03 firewall01 kernel: IN=eth0 OUT=eth2 SRC=10.0.0.131 DST=69.171.237.34 LEN=52 TOS=0x00 PREC=0x00 TTL=127 ID=14287 DF PROTO=TCP SPT=51711 DPT=445 WINDOW=8192 RES=0x00 SYN URGP=0

[c] Aug 28 06:02:41 firewall01 kernel: IN=eth0 OUT=eth2 SRC=10.0.0.115 DST=173.194.33.47 LEN=52 TOS=0x00 PREC=0x00 TTL=127 ID=4558 DF PROTO=TCP SPT=49294 DPT=445 WINDOW=8192 RES=0x00 SYN URGP=0