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Bug 78104

Summary: xinetd / ftp DOS attack
Product: [Retired] Red Hat Linux Reporter: Stephen Samuel <samuel>
Component: xinetdAssignee: Trond Eivind Glomsrxd <teg>
Status: CLOSED NOTABUG QA Contact: Brock Organ <borgan>
Severity: high Docs Contact:
Priority: high    
Version: 7.3CC: jbeima, jn
Target Milestone: ---   
Target Release: ---   
Hardware: i386   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2002-12-03 20:24:19 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 77074    
Bug Blocks:    

Description Stephen Samuel 2002-11-19 03:12:34 UTC
From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.3a) Gecko/20021111

Description of problem:
Opening and then quickly closing multiple sessions to ftp can cause a hang. 
This may be an xinetd problem or a kernel problem

Version-Release number of selected component (if applicable):


How reproducible:
Always

Steps to Reproduce:
1. start up xinetd with ftp
2. wait for an attack.
3.
	

Actual Results:  a connection to port 21 will result in only 
syn-ack  packets -- as if subsequent incomming packets aren't
even recieved.

Doesn't even respond to a fin-ack or rst packet

Expected Results:  Should respond properly to subsequent packets.

Additional info:

This is related to bug 77074. (more notes and attachments there)

These DOS attacks may be the only way that these lockups are likely to occur, 
or the DOS may be just be exploiting the bug that caused the original lockups.

NB: The machine that locks up is a dual processor box with multiple IP addresses.
(This may or may not have something to do with the problem)

associated RPMs:
ftp-0.17-13
wu-ftpd-2.6.2-5
anonftp-4.0-9
ncftp-3.1.3-3
ftpcopy-0.3.9-1
xinetd-2.3.9-0.73
kernel-bigmem-2.4.18-18.7.x