Solved

port 445 always open and sending syn ack packets.

Posted on 2004-09-10
6
1,535 Views
Last Modified: 2012-05-05
dear sir ,
i have a huge network , for about 3000 clients , using xp , win2k , 2003 , 98 , linux etc
all clients using win xp , 2000 , or 2003  are sending many packets using port 445 .
i can see the traffic from my routers
i thought it is the sasser  or the Gaobot , because it attacks on port 445 , i scanned many times with the utility that symantec provides it but nothing found .
is there any solution ?
0
Comment
Question by:skynoc
6 Comments
 
LVL 7

Accepted Solution

by:
LimeSMJ earned 500 total points
ID: 12025055
Windows XP, 2000, and 2003 use port 445 for SMB (Server Message Blocks)... instead of using NetBIOS over TCP/IP (ports 137-139) for SMB, these operating systems can directly send SMBs over TCP/IP.  The SMB protocol is used for Microsoft File and Printer sharing, so if your network needs it, just leave it.  These packets are OK as long as they are BEHIND your firewall.  SMB's should NEVER be passed onto the Internet as it poses a very high security risk.

If you are not using File and Printer sharing on your network at all, you can disable SMBs:

http://www.uksecurityonline.com/husdg/windows2000/close445.htm

Otherwise, make sure you block port 445 on your firewall (both incoming and outgoing).
0
 

Author Comment

by:skynoc
ID: 12025937
i did this before , but nothing has been changed ,
the virus uses this port to send packets .
but what kind of viruses is this. i scanned for sasser and gaobot ,
because they uses port 445.
0
 
LVL 23

Expert Comment

by:Tim Holman
ID: 12027565
It ISN'T a virus - this is NORMAL COMMUNICATION.
0
Ransomware: The New Cyber Threat & How to Stop It

This infographic explains ransomware, type of malware that blocks access to your files or your systems and holds them hostage until a ransom is paid. It also examines the different types of ransomware and explains what you can do to thwart this sinister online threat.  

 

Author Comment

by:skynoc
ID: 12028002
i followed the link you gave me before , i found that i did that many times before .
many computers are sending millions of packets , my routers track this traffic and they found they are attacking on port 445 and ( 135 to 138 tcp ) and port 139 udp
0
 
LVL 1

Expert Comment

by:Keravi
ID: 12036293
Port 135 on your windows machines could be DCOM and can be turned off using "dcomcnfg.exe" or using a variety of other methods, just google for "disable dcom windows" and check out the myriad of results, one should fit your scenario. Some viruses famous for exploiting this were MSBlast and Lovesan.

You mention that you see an "attack". What is the nature of this attack? How large are the packet sizes? TCP? UDP? Both? Do you have a plain text packet capture log snippet that you can share with us to help diagnose your problem?

You said that you followed the link and "did that many times before". Does this mean that you disabled port 445 as per the suggestion of LimeSMJ and a computer in question was still sending packets out on port 445?

Which side of your router is picking up this traffic? Do you have ingress filters and do they disallow internal IPs from being able to originate from outside your network?

We're going to need more information in order to solve this one.
0
 
LVL 23

Expert Comment

by:Tim Holman
ID: 12043549
Sounds a little out of the ordinary, in that case.
Can you identify a problem machine, and run netstat -an on it ?
Is it spawning excessive 445 connections ?
Something like Stinger would remove Sasser.  I believe Enterprise AV software becomes infected/disabled by Sasser and the likes, so reports everything as normal...

http://vil.nai.com/vil/stinger/
0

Featured Post

Networking for the Cloud Era

Join Microsoft and Riverbed for a discussion and demonstration of enhancements to SteelConnect:
-One-click orchestration and cloud connectivity in Azure environments
-Tight integration of SD-WAN and WAN optimization capabilities
-Scalability and resiliency equal to a data center

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

This article outlines the process to identify and resolve account lockout in an Active Directory environment.
The related questions "How do I recover the passwords for my Q-See DVR" and "How can I reset my Q-See DVR to eliminate a password" are seen several times a week.  Here we discuss the grim reality of the situation.
Sending a Secure fax is easy with eFax Corporate (http://www.enterprise.efax.com). First, Just open a new email message.  In the To field, type your recipient's fax number @efaxsend.com. You can even send a secure international fax — just include t…
With Secure Portal Encryption, the recipient is sent a link to their email address directing them to the email laundry delivery page. From there, the recipient will be required to enter a user name and password to enter the page. Once the recipient …

808 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question