[CentOS] VSFTPD accepting same user/session from different IP addresses

2010-03-22 Thread Dirk H. Schulz

Hi folks,

I have found the following in my logs:

Wed Mar 10 15:52:33 2010 [pid 15232] [uploaduser] OK MKDIR: Client 
195.200.70.*40*, /04 LV gelieferte Daten 04_2010/04 LV 
Seiten/Jungz?chter
Wed Mar 10 15:52:33 2010 [pid 15231] [uploaduser] FAIL MKDIR: Client 
195.200.70.*41*, /04 LV gelieferte Daten 04_2010/04 LV 
Seiten/Jungz?chter
Wed Mar 10 15:52:36 2010 [pid 15232] [uploaduser] OK UPLOAD: Client 
195.200.70.*40*, /04 LV gelieferte Daten 04_2010/04 LV 
Seiten/Jungz?chter/Kooperationsseminar.doc, 23552 bytes, 13.89Kbyte/sec
Wed Mar 10 15:52:37 2010 [pid 15231] [uploaduser] OK UPLOAD: Client 
195.200.70.*41*, /04 LV gelieferte Daten 04_2010/04 LV 
Seiten/Jungz?chter/Veranstaltungen der Jungz?chter im Jahr 2010.doc, 
23552 bytes, 9.07Kbyte/sec
Wed Mar 10 15:52:38 2010 [pid 15232] [uploaduser] OK UPLOAD: Client 
195.200.70.*40*, /04 LV gelieferte Daten 04_2010/04 LV 
Seiten/Jungz?chter/Foto Kooperationsseminar von laura weber.JPG, 13445 
bytes, 9.90Kbyte/sec


What I am concerned about is the fact that the client sends out using 
various gateways at once. Is there some configuration item in VSFTPD 
which can prevent this and reject packets from the additional ip addresses?


Any hint or help is appreciated.

Dirk


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Re: [CentOS] VSFTPD accepting same user/session from different IP addresses

2010-03-22 Thread Kai Schaetzl
Dirk H. Schulz wrote on Mon, 22 Mar 2010 13:41:50 +0100:

 What I am concerned about is the fact that the client sends out using 
 various gateways at once. Is there some configuration item in VSFTPD 
 which can prevent this and reject packets from the additional ip addresses?

Note, this is not the same session, it's a different connect with the same 
user credentials. I don't see a problem with this. It's not a security 
problem and it's hardly a load problem. Users usually don't have more than 
one IP at their disposal at the same time. This is one of the few cases where 
this is different.

AFAIK, there is no option to allow only x logins per user, only x logins per 
IP. You could go to the vsftpd mailing list (if there is one) and ask about 
this additional feature.

Kai

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Re: [CentOS] VSFTPD accepting same user/session from different IP addresses

2010-03-22 Thread Dirk H. Schulz
Hi Kai,

Am 22.03.10 15:31, schrieb Kai Schaetzl:
 Dirk H. Schulz wrote on Mon, 22 Mar 2010 13:41:50 +0100:


 What I am concerned about is the fact that the client sends out using
 various gateways at once. Is there some configuration item in VSFTPD
 which can prevent this and reject packets from the additional ip addresses?
  
 Note, this is not the same session, it's a different connect with the same
 user credentials. I don't see a problem with this. It's not a security
 problem and it's hardly a load problem. Users usually don't have more than
 one IP at their disposal at the same time. This is one of the few cases where
 this is different.

Thanks for the fast answer - and sorry for insisting. This
 Wed Mar 10 15:52:33 2010 [pid 15232] [uploaduser] OK MKDIR: Client 
 195.200.70.40, /04 LV gelieferte Daten 04_2010/04 LV 
 Seiten/Jungz?chter
 Wed Mar 10 15:52:33 2010 [pid 15231] [uploaduser] FAIL MKDIR: Client 
 195.200.70.41, /04 LV gelieferte Daten 04_2010/04 LV 
 Seiten/Jungz?chter
makes me think that the same session with the same commands is 
delivered via 2 outgoing gateways, because it would be very 
complicated to have two ftp clients issue the same command in the same 
second. Know what I mean?

By the way, vsftpd seems not to handle this situation securely, so I 
want to prevent any occurance of it.

Dirk
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Re: [CentOS] VSFTPD accepting same user/session from different IP addresses

2010-03-22 Thread Kai Schaetzl
Dirk H. Schulz wrote on Mon, 22 Mar 2010 15:41:55 +0100:

 makes me think that the same session with the same commands is 
 delivered via 2 outgoing gateways, because it would be very 
 complicated to have two ftp clients issue the same command in the same 
 second. Know what I mean?

No, I don't know. This is *one* client and I bet it's the dreaded 
Filezilla. It opens multiple parallel connections if you don't configure 
it correctly. And then it's just a matter of how your internet connection 
and gateway is setup. This is a big institution with a big IP range 
(whois.ripe.net). It's not your usual type of connection, but it's nothing 
wrong with it.

 
 By the way, vsftpd seems not to handle this situation securely, so I 
 want to prevent any occurance of it.

Again, what's the security problem here?


Kai

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