Red Hat Bugzilla – Bug 78104
xinetd / ftp DOS attack
Last modified: 2005-10-31 17:00:50 EST
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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):
Steps to Reproduce:
1. start up xinetd with ftp
2. wait for an attack.
Actual Results: a connection to port 21 will result in only
syn-ack packets -- as if subsequent incomming packets aren't
Doesn't even respond to a fin-ack or rst packet
Expected Results: Should respond properly to subsequent packets.
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)