Jump to content

TCP/IP stack fingerprinting: Difference between revisions

From Wikipedia, the free encyclopedia
Browse history interactively
← Previous editNext edit →
Content deleted Content added
VisualWikitext
Filling in 8 references using Reflinks, see also Fingerprinting tools section
Line 5: Line 5:
== TCP/IP Fingerprint Specifics ==
== TCP/IP Fingerprint Specifics ==


Certain parameters within the [[TCP protocol]] definition are left up to the implementation.  Different operating systems, and different versions of the same operating system, set different defaults for these values.  By collecting and examining these values, one may differentiate among various operating systems, and implementations of TCP/IP.<ref>[http://project.honeynet.org/papers/finger/ Know Your Enemy: Passive Fingerprinting]</ref> The TCP/IP fields that may vary
Certain parameters within the [[TCP protocol]] definition are left up to the implementation.  Different operating systems, and different versions of the same operating system, set different defaults for these values.  By collecting and examining these values, one may differentiate among various operating systems, and implementations of TCP/IP.<ref>{{cite web|url=http://project.honeynet.org/papers/finger/ |title=Know Your Enemy: Passive Fingerprinting |publisher=Project.honeynet.org |date= |accessdate=2011-11-25}}</ref> The TCP/IP fields that may vary
include the following:
include the following:


Line 17: Line 17:
* "nop" flag (1 bit)
* "nop" flag (1 bit)


These values may be combined to form a 67-bit signature, or fingerprint, for the target machine.<ref>Chuvakin A. and Peikari, C: "Security Warrior.", page 229. O'Reilly Media Inc., 2004.</ref> Just inspecting the Initial TTL and window size fields is often enough in order to successfully identify an operating system, which eases the task of performing manual OS fingerprinting<ref>[http://www.netresec.com/?page=Blog&month=2011-11&post=Passive-OS-Fingerprinting Passive OS Fingerprinting, NETRESEC Network Security Blog]</ref>.
These values may be combined to form a 67-bit signature, or fingerprint, for the target machine.<ref>Chuvakin A. and Peikari, C: "Security Warrior.", page 229. O'Reilly Media Inc., 2004.</ref> Just inspecting the Initial TTL and window size fields is often enough in order to successfully identify an operating system, which eases the task of performing manual OS fingerprinting.<ref>{{cite web|url=http://www.netresec.com/?page=Blog&month=2011-11&post=Passive-OS-Fingerprinting |title=Passive OS Fingerprinting, NETRESEC Network Security Blog |publisher=Netresec.com |date=2011-11-05 |accessdate=2011-11-25}}</ref>


== Protection against and detecting fingerprinting ==
== Protection against and detecting fingerprinting ==
Protection against all types of TCP/IP fingerprinting is achieved through TCP/IP fingerprint obfuscators. Also known as fingerprint scrubbing, tools exist for [[MS Windows]],<ref>[http://www.irongeek.com/i.php?page=security/osfuscate-change-your-windows-os-tcp-ip-fingerprint-to-confuse-p0f-networkminer-ettercap-nmap-and-other-os-detection-tools OSfuscate]</ref> [[Linux]],<ref>[http://ippersonality.sourceforge.net/ IPPersonality]</ref> [[FreeBSD]],<ref>[http://www.usenix.org/events/sec00/full_papers/smart/smart_html/index.html Defeating TCP/IP stack fingerprinting]</ref> and likely others.
Protection against all types of TCP/IP fingerprinting is achieved through TCP/IP fingerprint obfuscators. Also known as fingerprint scrubbing, tools exist for [[MS Windows]],<ref>{{cite web|url=http://www.irongeek.com/i.php?page=security/osfuscate-change-your-windows-os-tcp-ip-fingerprint-to-confuse-p0f-networkminer-ettercap-nmap-and-other-os-detection-tools |title=OSfuscate |publisher=Irongeek.com |date=2008-09-30 |accessdate=2011-11-25}}</ref> [[Linux]],<ref>{{cite web|author=Carl-Daniel Hailfinger, carldani@4100XCDT |url=http://ippersonality.sourceforge.net/ |title=IPPersonality |publisher=Ippersonality.sourceforge.net |date= |accessdate=2011-11-25}}</ref> [[FreeBSD]],<ref>{{cite web|url=http://www.usenix.org/events/sec00/full_papers/smart/smart_html/index.html |title=Defeating TCP/IP stack fingerprinting |publisher=Usenix.org |date=2002-01-29 |accessdate=2011-11-25}}</ref> and likely others.


Moreover, protection against active fingerprinting attempts is achieved by limiting the type and amount of traffic a system responds to. Examples include the following: blocking of all unnecessary outgoing [[Internet Control Message Protocol|ICMP]] traffic, especially unusual packet types like address masks and timestamps. Also, blocking of any [[ICMP Echo Reply|ICMP echo replies]]. Be warned that blocking things without knowing exactly what they are for can very well lead to a broken network; for instance, your network could become a [[Black hole (networking)|black hole]]. Alternatively, active fingerprinting tools themselves have fingerprints that can be detected.<ref>[http://ojnk.sourceforge.net/stuff/iplog.readme iplog]</ref>
Moreover, protection against active fingerprinting attempts is achieved by limiting the type and amount of traffic a system responds to. Examples include the following: blocking of all unnecessary outgoing [[Internet Control Message Protocol|ICMP]] traffic, especially unusual packet types like address masks and timestamps. Also, blocking of any [[ICMP Echo Reply|ICMP echo replies]]. Be warned that blocking things without knowing exactly what they are for can very well lead to a broken network; for instance, your network could become a [[Black hole (networking)|black hole]]. Alternatively, active fingerprinting tools themselves have fingerprints that can be detected.<ref>{{cite web|url=http://ojnk.sourceforge.net/stuff/iplog.readme |title=iplog |date= |accessdate=2011-11-25}}</ref>


Defeating TCP/IP fingerprinting may provide limited protection from potential attackers who employ a [[vulnerability scanner]] to select machines of a specific target OS. However, a determined adversary may simply try a series of different attacks until one is successful.<ref>http://seclists.org/pen-test/2007/Sep/0030.html OS detection not key to penetration</ref>
Defeating TCP/IP fingerprinting may provide limited protection from potential attackers who employ a [[vulnerability scanner]] to select machines of a specific target OS. However, a determined adversary may simply try a series of different attacks until one is successful.<ref>{{cite web|url=http://seclists.org/pen-test/2007/Sep/0030.html |title=OS detection not key to penetration |publisher=Seclists.org |date= |accessdate=2011-11-25}}</ref>


== Fingerprinting tools ==
== Fingerprinting tools ==
A list of TCP/OS Fingerprinting Tools
A list of TCP/OS Fingerprinting Tools
⚫
* [[PRADS]] - Passive comprehensive TCP/IP stack fingerprinting and service detection
* [[Ettercap (computing)|Ettercap]] - passive TCP/IP stack fingerprinting.
* [[Ettercap (computing)|Ettercap]] - passive TCP/IP stack fingerprinting.
* [[NetworkMiner]] - passive [[DHCP]] and TCP/IP stack fingerprinting (combines p0f, Ettercap and Satori databases)
* [[NetworkMiner]] - passive [[DHCP]] and TCP/IP stack fingerprinting (combines p0f, Ettercap and Satori databases)
* [[Nmap]] - comprehensive active stack fingerprinting.
* [[Nmap]] - comprehensive active stack fingerprinting.
* [[p0f]] - comprehensive passive TCP/IP stack fingerprinting.
* [[p0f]] - comprehensive passive TCP/IP stack fingerprinting.
* [[PacketFence]]<ref>[http://www.packetfence.org/ PacketFence]</ref> - open source [[Network Access Control|NAC]] with passive DHCP fingerprinting.
* [[PacketFence]]<ref>{{cite web|url=http://www.packetfence.org/ |title=PacketFence |publisher=PacketFence |date=2011-11-21 |accessdate=2011-11-25}}</ref> - open source [[Network Access Control|NAC]] with passive DHCP fingerprinting.
⚫
* [[PRADS]] - Passive comprehensive TCP/IP stack fingerprinting and service detection
* Satori - passive [[Cisco Discovery Protocol|CDP]], DHCP, ICMP, [[HP Switch Protocol|HPSP]], [[HTTP]], TCP/IP and other stack fingerprinting.
* Satori - passive [[Cisco Discovery Protocol|CDP]], DHCP, ICMP, [[HP Switch Protocol|HPSP]], [[HTTP]], TCP/IP and other stack fingerprinting.
* SinFP - single-port active/passive fingerprinting.
* SinFP - single-port active/passive fingerprinting.

Revision as of 15:46, 25 November 2011

Passive OS Fingerprinting method and diagram.

TCP/IP stack fingerprinting is the passive collection of configuration attributes from a remote device during standard layer 4 network communications. The combination of parameters may then be used to infer the remote machine's operating system (aka, OS fingerprinting), or incorporated into a device fingerprint.

TCP/IP Fingerprint Specifics

Certain parameters within the TCP protocol definition are left up to the implementation.  Different operating systems, and different versions of the same operating system, set different defaults for these values.  By collecting and examining these values, one may differentiate among various operating systems, and implementations of TCP/IP.[1] The TCP/IP fields that may vary include the following:

  • Initial packet size (16 bits)
  • Initial TTL (8 bits)
  • Window size (16 bits)
  • Max segment size (16 bits)
  • Window scaling value (8 bits)
  • "don't fragment" flag (1 bit)
  • "sackOK" flag (1 bit)
  • "nop" flag (1 bit)

These values may be combined to form a 67-bit signature, or fingerprint, for the target machine.[2] Just inspecting the Initial TTL and window size fields is often enough in order to successfully identify an operating system, which eases the task of performing manual OS fingerprinting.[3]

Protection against and detecting fingerprinting

Protection against all types of TCP/IP fingerprinting is achieved through TCP/IP fingerprint obfuscators. Also known as fingerprint scrubbing, tools exist for MS Windows,[4] Linux,[5] FreeBSD,[6] and likely others.

Moreover, protection against active fingerprinting attempts is achieved by limiting the type and amount of traffic a system responds to. Examples include the following: blocking of all unnecessary outgoing ICMP traffic, especially unusual packet types like address masks and timestamps. Also, blocking of any ICMP echo replies. Be warned that blocking things without knowing exactly what they are for can very well lead to a broken network; for instance, your network could become a black hole. Alternatively, active fingerprinting tools themselves have fingerprints that can be detected.[7]

Defeating TCP/IP fingerprinting may provide limited protection from potential attackers who employ a vulnerability scanner to select machines of a specific target OS. However, a determined adversary may simply try a series of different attacks until one is successful.[8]

Fingerprinting tools

A list of TCP/OS Fingerprinting Tools

  • Ettercap - passive TCP/IP stack fingerprinting.
  • NetworkMiner - passive DHCP and TCP/IP stack fingerprinting (combines p0f, Ettercap and Satori databases)
  • Nmap - comprehensive active stack fingerprinting.
  • p0f - comprehensive passive TCP/IP stack fingerprinting.
  • PacketFence[9] - open source NAC with passive DHCP fingerprinting.
  • PRADS - Passive comprehensive TCP/IP stack fingerprinting and service detection
  • Satori - passive CDP, DHCP, ICMP, HPSP, HTTP, TCP/IP and other stack fingerprinting.
  • SinFP - single-port active/passive fingerprinting.
  • XProbe2 - active TCP/IP stack fingerprinting.

References

  1. ^ "Know Your Enemy: Passive Fingerprinting". Project.honeynet.org. Retrieved 2011-11-25.
  2. ^ Chuvakin A. and Peikari, C: "Security Warrior.", page 229. O'Reilly Media Inc., 2004.
  3. ^ "Passive OS Fingerprinting, NETRESEC Network Security Blog". Netresec.com. 2011-11-05. Retrieved 2011-11-25.
  4. ^ "OSfuscate". Irongeek.com. 2008-09-30. Retrieved 2011-11-25.
  5. ^ Carl-Daniel Hailfinger, carldani@4100XCDT. "IPPersonality". Ippersonality.sourceforge.net. Retrieved 2011-11-25.{{cite web}}: CS1 maint: numeric names: authors list (link)
  6. ^ "Defeating TCP/IP stack fingerprinting". Usenix.org. 2002-01-29. Retrieved 2011-11-25.
  7. ^ "iplog". Retrieved 2011-11-25.
  8. ^ "OS detection not key to penetration". Seclists.org. Retrieved 2011-11-25.
  9. ^ "PacketFence". PacketFence. 2011-11-21. Retrieved 2011-11-25.

External links

Retrieved from "https://en.wikipedia.org/w/index.php?title=TCP/IP_stack_fingerprinting&oldid=462420582"