例のDLLでLOGをとってみました。

gethostname(ｽ9 +ﾔ, 260)
gethostbyname(main-notepc) = 001EB730
getsockname(0x594, 0013E4A4, 1303740)
WSAStartup(0x101,0013E45C) = 0
socket(0x2, 0x1, 0) = 0x648
htons(6891)
WSAAsyncSelect(0x648, 01431114, 0x428, 0x3b)
bind(0x648, 0013E5B8, 0x10)
listen(0x648, 2147483647)
inet_ntoa(285321408)
msmIP:こっちのグローバルなIPアドレス
msmPort:6891
gethostname( ﾙ, 255)
gethostbyname(main-notepc) = 001EB730
inet_ntoa(-2127517504)
old_str: IP-Address: 192.168.48.129
new_str: IP-Address: こっちのグローバルなIPアドレス
new_buf: MSG 115 U 244
MIME-Version: 1.0
Content-Type: text/x-msmsgsinvite; charset=UTF-8

Invitation-Command: ACCEPT
Invitation-Cookie: 87568998
IP-Address: 192.168.1.17
Port: 6891
AuthCookie: 99902792
Launch-Application: FALSE
Request-Data: IP-Address:


ﾝ
new_str2: Port: 6891
***** send start *****
send(0x598, 0013D750, 0x103, 0)
MSG 115 U 244
MIME-Version: 1.0
Content-Type: text/x-msmsgsinvite; charset=UTF-8

Invitation-Command: ACCEPT
Invitation-Cookie: 87568998
IP-Address: 192.168.1.17
Port: 6891
AuthCookie: 99902792
Launch-Application: FALSE
Request-Data: IP-Address:


***** send end *****

っていう感じです。