Re: firewalls - Kerio PF Part 1 - what to block and why - your security at risk
Re: firewalls - Kerio PF Part 1 - what to block and why - your security at risk
To no one directly, but to all who have interest:
Before we completely stop this thread, and it fades away, I thought I
should display how a persistent contact attempt may show up in a firewall
log, and how one can use the log to help secure a system.
I'll use the Shaw aspect as I have previously referenced this entity [again
this is just logon and mail retrieval]:
1,[31/Jul/2007 23:40:44] Rule 'Shaw Comm block': Blocked: In UDP,
24.64.28.88:6950->localhost:1026, Owner: no owner
1,[31/Jul/2007 23:40:44] Rule 'Shaw Comm block': Blocked: In UDP,
24.64.28.88:6950->localhost:1027, Owner: no owner
1,[31/Jul/2007 23:40:44] Rule 'Shaw Comm block': Blocked: In UDP,
24.64.28.88:6950->localhost:1028, Owner: no owner
1,[31/Jul/2007 23:41:24] Rule 'Shaw Comm block': Blocked: In UDP,
24.64.75.177:29736->localhost:1026, Owner: no owner
1,[31/Jul/2007 23:41:24] Rule 'Shaw Comm block': Blocked: In UDP,
24.64.75.177:29736->localhost:1027, Owner: no owner
1,[31/Jul/2007 23:41:24] Rule 'Shaw Comm block': Blocked: In UDP,
24.64.75.177:29736->localhost:1028, Owner: no owner
Next we see a distinct switch in tactics, to an out of Shaw range and
TCP...
1,[31/Jul/2007 23:41:34] Rule 'Packet to unopened port received': Blocked:
In TCP, S010600508df5db23.ed.shawcable.net
[68.149.172.142:33745]->localhost:6346, Owner: no owner
1,[31/Jul/2007 23:41:36] Rule 'Packet to unopened port received': Blocked:
In TCP, S010600508df5db23.ed.shawcable.net
[68.149.172.142:33745]->localhost:6346, Owner: no owner
1,[31/Jul/2007 23:41:42] Rule 'Packet to unopened port received': Blocked:
In TCP, S010600508df5db23.ed.shawcable.net
[68.149.172.142:33745]->localhost:6346, Owner: no owner
1,[31/Jul/2007 23:43:14] Rule 'Packet to unopened port received': Blocked:
In TCP, S010600508df5db23.ed.shawcable.net
[68.149.172.142:63441]->localhost:6346, Owner: no owner
1,[31/Jul/2007 23:43:18] Rule 'Packet to unopened port received': Blocked:
In TCP, S010600508df5db23.ed.shawcable.net
[68.149.172.142:63441]->localhost:6346, Owner: no owner
1,[31/Jul/2007 23:43:24] Rule 'Packet to unopened port received': Blocked:
In TCP, S010600508df5db23.ed.shawcable.net
[68.149.172.142:63441]->localhost:6346, Owner: no owner
1,[31/Jul/2007 23:44:46] Rule 'Packet to unopened port received': Blocked:
In TCP, S010600508df5db23.ed.shawcable.net
[68.149.172.142:42961]->localhost:6346, Owner: no owner
1,[31/Jul/2007 23:44:54] Rule 'Packet to unopened port received': Blocked:
In TCP, S010600508df5db23.ed.shawcable.net
[68.149.172.142:42961]->localhost:6346, Owner: no owner
We do find though, the unique identifier and time and date, which supplies
sufficient material were this a subpoena matter [server logs], or something
one wished to trace [as it occurred], or was suspect of a hack attempt.
For reference, here was the range as posted by PCR:
OrgName: Shaw Communications Inc.
OrgID: SHAWC
Address: Suite 800
Address: 630 - 3rd Ave. SW
City: Calgary
StateProv: AB
PostalCode: T2P-4L4
Country: CA
ReferralServer: rwhois://rs1so.cg.shawcable.net:4321
NetRange: 24.64.0.0 - 24.71.255.255
CIDR: 24.64.0.0/13
NetName: SHAW-COMM
NetHandle: NET-24-64-0-0-1
Parent: NET-24-0-0-0-0
NetType: Direct Allocation
NameServer: NS7.NO.CG.SHAWCABLE.NET
NameServer: NS8.SO.CG.SHAWCABLE.NET
Comment:
RegDate: 1996-06-03
Updated: 2006-02-08
And last, the *shawcable.net* address so we can again visualize the above
as a referenced Shaw attempt, and another unique identifier.
1,[02/Aug/2007 01:03:40] Rule 'Shaw Comm block': Blocked: In UDP,
S0106000ae6120fdf.cg.shawcable.net [24.64.120.223:16547]->localhost:1028,
Owner: no owner
So finding out a range of addresses gives one opportunity to address
specific issues by blocking them using the range, and your general blocks
*with logging* provide additional information which you can use to determine
other potential issues.
---
This post is to display how important and useful firewall logs can be.
A set of rules properly setup can keep out things we may not wish to enter
our systems, and help monitor what is actually occurring as we travel the
Internet.
Keep it in mind when setting up, and monitoring your security..
--
MEB
http://peoplescounsel.orgfree.com
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