* strange log
@ 2003-05-02 9:47 Keith Tin
2003-05-03 23:29 ` Cedric Blancher
0 siblings, 1 reply; 6+ messages in thread
From: Keith Tin @ 2003-05-02 9:47 UTC (permalink / raw)
To: netfilter
[-- Attachment #1: Type: text/plain, Size: 487 bytes --]
Hi, I found something strange in my iptables log. It was strange because I put my server at ISP and I don't know why there was an internal IP logged by my server. May 2 16:55:35 ABC kernel: FW-REJECT IN=eth0 OUT= MAC=ff:ff:ff:ff:ff:ff:00:10:5a:63:d3:d8:08:00 SRC=192.168.93.1 DST=255.255.255.255 LEN=276 TOS=0x00 PREC=0x00 TTL=128 ID=34884 PROTO=UDP SPT=68 DPT=67 LEN=256 How can I block these kind of IP? Thanks, Keith
第二世(謝霆鋒)，習慣失戀(容祖兒)，兄妹(陳奕迅)...
Yahoo! 鈴聲下載
[-- Attachment #2: Type: text/html, Size: 1080 bytes --]
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: strange log
2003-05-02 9:47 Keith Tin
@ 2003-05-03 23:29 ` Cedric Blancher
2003-05-03 23:45 ` Alexander Demenshin
0 siblings, 1 reply; 6+ messages in thread
From: Cedric Blancher @ 2003-05-03 23:29 UTC (permalink / raw)
To: Keith Tin; +Cc: netfilter
Le ven 02/05/2003 à 11:47, Keith Tin a écrit :
> I found something strange in my iptables log. It was strange because I
> put my server at ISP and I don't know why there was an internal IP
> logged by my server.
>
> May 2 16:55:35 ABC kernel: FW-REJECT IN=eth0 OUT=
> MAC=ff:ff:ff:ff:ff:ff:00:10:5a:63:d3:d8:08:00 SRC=192.168.93.1
> DST=255.255.255.255 LEN=276 TOS=0x00 PREC=0x00 TTL=128 ID=34884
> PROTO=UDP SPT=68 DPT=67 LEN=256
Broadcast UDP packet from port 68 to port 67
$ grep 6[78]/udp /etc/services
bootps 67/udp
bootpc 68/udp
[...]
This is DHCP request from client to server. For client already has an
IP, I would say it is a DHCP request confirmation or a bail renewal.
> How can I block these kind of IP?
Block all private IPs if they're not supposed to reach your server.
I agree it's quite unsual to see DHCP stuff within a hosting
infrastructure.
--
Cédric Blancher <blancher@cartel-securite.fr>
IT systems and networks security - Cartel Sécurité
Phone : +33 (0)1 44 06 97 87 - Fax: +33 (0)1 44 06 97 99
PGP KeyID:157E98EE FingerPrint:FA62226DA9E72FA8AECAA240008B480E157E98EE
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: strange log
2003-05-03 23:29 ` Cedric Blancher
@ 2003-05-03 23:45 ` Alexander Demenshin
2003-05-04 0:10 ` Cedric Blancher
0 siblings, 1 reply; 6+ messages in thread
From: Alexander Demenshin @ 2003-05-03 23:45 UTC (permalink / raw)
To: netfilter
On Sun, May 04, 2003 at 01:29:18AM +0200, Cedric Blancher wrote:
> I agree it's quite unsual to see DHCP stuff within a hosting
> infrastructure.
It depends. Some ISP use DHCP to assign IP addresses to customer's
servers.
Regards,
/Al
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: strange log
2003-05-03 23:45 ` Alexander Demenshin
@ 2003-05-04 0:10 ` Cedric Blancher
2003-05-04 0:35 ` Alexander Demenshin
0 siblings, 1 reply; 6+ messages in thread
From: Cedric Blancher @ 2003-05-04 0:10 UTC (permalink / raw)
To: Alexander Demenshin; +Cc: netfilter
Le dim 04/05/2003 à 01:45, Alexander Demenshin a écrit :
> It depends. Some ISP use DHCP to assign IP addresses to customer's
> servers.
DHCP is a very weak system from security point of vue, that can easily
lead to DoS and traffic redirection. A customer server compromise could
be a serious threat for other servers...
--
Cédric Blancher <blancher@cartel-securite.fr>
IT systems and networks security - Cartel Sécurité
Phone : +33 (0)1 44 06 97 87 - Fax: +33 (0)1 44 06 97 99
PGP KeyID:157E98EE FingerPrint:FA62226DA9E72FA8AECAA240008B480E157E98EE
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: strange log
2003-05-04 0:10 ` Cedric Blancher
@ 2003-05-04 0:35 ` Alexander Demenshin
0 siblings, 0 replies; 6+ messages in thread
From: Alexander Demenshin @ 2003-05-04 0:35 UTC (permalink / raw)
To: netfilter
On Sun, May 04, 2003 at 02:10:24AM +0200, Cedric Blancher wrote:
> DHCP is a very weak system from security point of vue, that can easily
> lead to DoS and traffic redirection.
When you have few hundreths servers, there is no better way to
assign/change IPs. And even without DHCP, there are a lot of ways
for traffic redirection (ARP poisoning and so on).
> A customer server compromise could be a serious threat for other servers...
When server is not managed, or when attacker is inside of hosting segment
- perhaps. But when attacker is outside - there is no way to compromise
the host through DHCP. If it is compromised by other means - DHCP is not the
cause, so? :)
Even MAC filtering is weak - modern NICs may have any MAC, it is configurable.
No system is secure - unless it is plugged off and burned out. And even then...
but this is another story :)
Regards,
/Al
^ permalink raw reply [flat|nested] 6+ messages in thread
* strange log
@ 2004-04-22 6:50 Emilio Casbas
0 siblings, 0 replies; 6+ messages in thread
From: Emilio Casbas @ 2004-04-22 6:50 UTC (permalink / raw)
To: netfilter
[-- Attachment #1: Type: text/plain, Size: 337 bytes --]
Hi,
We've seen in the firewall's log of transparent proxy this messege from
different ips repeteadly :
Apr 21 21:28:55 moria kernel: TCP: Treason uncloaked! Peer
external_ip/80 shrinks window 1466359669:1466360884. Repaired.
We've googling, but we dont know if is an attack or a bad negotiation.
Any suggestion?
Thanks
Emilio C.
[-- Attachment #2: S/MIME Cryptographic Signature --]
[-- Type: application/x-pkcs7-signature, Size: 3958 bytes --]
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2004-04-22 6:50 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2004-04-22 6:50 strange log Emilio Casbas
-- strict thread matches above, loose matches on Subject: below --
2003-05-02 9:47 Keith Tin
2003-05-03 23:29 ` Cedric Blancher
2003-05-03 23:45 ` Alexander Demenshin
2003-05-04 0:10 ` Cedric Blancher
2003-05-04 0:35 ` Alexander Demenshin
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox