MSN Messenger and UDP 1900

From: Louie Martinez (louieat_private)
Date: Tue Feb 05 2002 - 18:15:09 PST

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    I had noticed I had been getting these curious entries in my logfile on my 
    linux box which is set up as a firewall. (I use Shorewall to manage IPTables)
    
    Feb  5 17:37:07 firewall kernel: Shorewall:all2all:REJECT:IN=eth1 OUT= 
    MAC=00:a0:cc:3f:64:00:00:e0:7d:b8:78:72:08:00 SRC=192.
    168.1.18 DST=192.168.1.1 LEN=160 TOS=0x00 PREC=0x00 TTL=128 ID=1638 
    PROTO=UDP SPT=1148 DPT=1900 LEN=140
    Feb  5 17:42:04 firewall kernel: Shorewall:all2all:REJECT:IN=eth1 OUT= 
    MAC=00:a0:cc:3f:64:00:00:02:e3:11:b7:cc:08:00 SRC=192.
    168.1.4 DST=192.168.1.1 LEN=160 TOS=0x00 PREC=0x00 TTL=128 ID=5080 
    PROTO=UDP SPT=1211 DPT=1900 LEN=140
    
    These happen to be Windows XP machines. The curious part is that I have 
    properly disabled UPnP and SSDP Discovery on both system.
    
    With some investigating I managed to view the payload of the mysterious UDP 
    packet.
    
    M-SEARCH * HTTP/1.1
    HOST: 239.255.255.250:1900
    MAN: "ssdp:discover"
    MX: 3
    ST: urn:schemas-upnp-org:service:WANIPConnection:1
    
    Anyway after even further investigation it seems that these mysterious 
    packets are only sent if MSN messenger is launched. You don't even have to 
    be logged into your MSN Messenger account. As long as it's sitting in your 
    system tray, these packets seem to be sent every 10 to 15 seconds on 
    machines with active MSN accounts and every 5 minutes or so on machines 
    that haven't set up an MSN Messenger acount but still leave it sitting in 
    the system tray.
    
    If anyone else can confirm this or know why MSN wants to talk like a UPnP 
    device, I'd be appreciative to hear from you.
    



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