Network Working Group M. Tuexen, Ed.
Internet-Draft Muenster Univ. of Appl. Sciences
Intended status: Informational F. Risso
Expires: 7 April 2022 Politecnico di Torino
J. Bongertz
Airbus DS CyberSecurity
G. Combs
Wireshark
G. Harris
E. Chaudron
Red Hat
M. Richardson
Sandelman
4 October 2021
Additional block types for PCAP Next Generation (pcapng) Capture File
Format
draft-richardson-opsawg-pcapng-extras-00
Abstract
This document contains a number of extensions to the PCAPng file
format which are outside of the IETF networking mandate.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 7 April 2022.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
Tuexen, et al. Expires 7 April 2022 [Page 1]
Internet-Draft pcapng October 2021
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Simplified BSD License text
as described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Simplified BSD License.
Table of Contents
1. Introduction to Additional Block Types . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Additional Block Types . . . . . . . . . . . . . . . . . . . 2
3.1. systemd Journal Export Block . . . . . . . . . . . . . . 3
3.2. Alternative Packet Blocks (experimental) . . . . . . . . 4
3.3. Compression Block (experimental) . . . . . . . . . . . . 4
3.4. Encryption Block (experimental) . . . . . . . . . . . . . 5
3.5. Fixed Length Block (experimental) . . . . . . . . . . . . 6
3.6. Directory Block (experimental) . . . . . . . . . . . . . 7
3.7. Traffic Statistics and Monitoring Blocks
(experimental) . . . . . . . . . . . . . . . . . . . . . 7
3.8. Event/Security Block (experimental) . . . . . . . . . . . 7
4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 8
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction to Additional Block Types
TBD
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Additional Block Types
Tuexen, et al. Expires 7 April 2022 [Page 2]
Internet-Draft pcapng October 2021
3.1. systemd Journal Export Block
The systemd (https://www.freedesktop.org/wiki/Software/systemd/)
Journal Export Block
(https://www.freedesktop.org/wiki/Software/systemd/export/) is a
lightweight container for systemd Journal Export Format entry data.
One of the primary components of the systemd System and Service
Manager is the "Journal", a message logging system that uses arrays
of key-value pairs. Journal entries are stored in a database-like
file on disk but can be serialized to easily parseable "Journal
Export Format" data or to a JSON object. The block described here is
limited to Journal Export Format data only.
A systemd Journal Export Block contains a single systemd Journal
Export Format entry. Each entry MUST contain a __REALTIME_TIMESTAMP=
field. If a timestamp for the block is required it can be derived
from this field. Each entry MUST be zero-padded to 32 bits.
Although the primary use of this block is intended for importing data
from systemd, it could potentially be used to include arbitrary key-
value data in a capture file.
Figure 1 shows the format of the Journal Export Block.
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 | Block Type = 0x00000009 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4 | Block Total Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
8 / /
/ Journal Entry /
/ variable length, padded to 32 bits /
/ /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Block Total Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: systemd Journal Export Block Format
The systemd Journal Export Block has the following fields:
* Block Type: The block type of the Journal Export Block is 9.
* Block Total Length: total size of this block, as described in
[I-D.tuexen-opsawg-pcapng], section "Section Blocks".
Tuexen, et al. Expires 7 April 2022 [Page 3]
Internet-Draft pcapng October 2021
* Journal Entry: A journal entry as described in the Journal Export
Format (https://www.freedesktop.org/wiki/Software/systemd/export/)
documentation. Entries consist of a series of field names
followed by text or binary field data. Common field names can be
found in the systemd.journal-fields
(https://www.freedesktop.org/software/systemd/man/systemd.journal-
fields.html) documentation. The __REALTIME_TIMESTAMP= field MUST
be present and valid as described above. Entries are not
guaranteed to be a multiple of four octets and must be zero-
padded. This allows the length of the entry to be determined by
finding the last non-zero octet in the Journal Entry data. An
entry may contain an entry separator (trailing newline) as
described in the Journal Export Format specification
3.2. Alternative Packet Blocks (experimental)
Can some other packet blocks (besides the ones described in the
previous paragraphs) be useful?
3.3. Compression Block (experimental)
The Compression Block is optional. A file can contain an arbitrary
number of these blocks. A Compression Block, as the name says, is
used to store compressed data. Its format is shown in Figure 2.
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 | Block Type = ? |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4 | Block Total Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
8 | Compr. Type | /
+-+-+-+-+-+-+-+-+ /
/ /
/ Compressed Data /
/ /
/ variable length, octet-aligned and padded to end on a 32-bit /
/ boundary /
/ /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Block Total Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Compression Block Format
The fields have the following meaning:
Tuexen, et al. Expires 7 April 2022 [Page 4]
Internet-Draft pcapng October 2021
* Block Type: The block type of the Compression Block is not yet
assigned.
* Block Total Length: total size of this block, as described in
[I-D.tuexen-opsawg-pcapng], section "Section Blocks".
* Compression Type (8 bits): an unsigned value that specifies the
compression algorithm. Possible values for this field are 0
(uncompressed), 1 (Lempel-Ziv), 2 (Gzip), other?? Probably some
kind of dumb and fast compression algorithm could be effective
with some types of traffic (for example web), but which?
* Compressed Data: data of this block. Once decompressed, it is
made of other blocks.
3.4. Encryption Block (experimental)
The Encryption Block is optional. A file can contain an arbitrary
number of these blocks. An Encryption Block is used to store
encrypted data. Its format is shown in Figure 3.
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 | Block Type = ? |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4 | Block Total Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
8 | Encr. Type | /
+-+-+-+-+-+-+-+-+ /
/ /
/ Encrypted Data /
/ /
/ variable length, octet-aligned /
/ /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Block Total Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Encryption Block Format
The fields have the following meaning:
* Block Type: The block type of the Encryption Block is not yet
assigned.
* Block Total Length: total size of this block, as described in
[I-D.tuexen-opsawg-pcapng], section "Section Blocks".
Tuexen, et al. Expires 7 April 2022 [Page 5]
Internet-Draft pcapng October 2021
* Encryption Type (8 bits): an unsigned value that specifies the
encryption algorithm. Possible values for this field are ???
(TODO) NOTE: this block should probably contain other fields,
depending on the encryption algorithm. To be defined precisely.
* Encrypted Data: data of this block. Once decrypted, it originates
other blocks.
3.5. Fixed Length Block (experimental)
The Fixed Length Block is optional. A file can contain an arbitrary
number of these blocks. A Fixed Length Block can be used to optimize
the access to the file. Its format is shown in Figure 4. A Fixed
Length Block stores records with constant size. It contains a set of
Blocks (normally Enhanced Packet Blocks or Simple Packet Blocks), of
which it specifies the size. Knowing this size a priori helps to
scan the file and to load some portions of it without truncating a
block, and is particularly useful with cell-based networks like ATM.
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 | Block Type = ? |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4 | Block Total Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
8 | Cell Size | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ /
/ /
/ Fixed Size Data /
/ /
/ variable length, octet-aligned /
/ /
/ /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Block Total Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Fixed Length Block Format
The fields have the following meaning:
* Block Type: The block type of the Fixed Length Block is not yet
assigned.
* Block Total Length: total size of this block, as described in
[I-D.tuexen-opsawg-pcapng], section "Section Blocks".
Tuexen, et al. Expires 7 April 2022 [Page 6]
Internet-Draft pcapng October 2021
* Cell size (16 bits): an unsigned value that indicates the size of
the blocks contained in the data field.
* Fixed Size Data: data of this block.
3.6. Directory Block (experimental)
If present, this block contains the following information:
* number of indexed packets (N)
* table with position and length of any indexed packet (N entries)
A directory block MUST be followed by at least N packets, otherwise
it MUST be considered invalid. It can be used to efficiently load
portions of the file to memory and to support operations on memory
mapped files. This block can be added by tools like network
analyzers as a consequence of file processing.
3.7. Traffic Statistics and Monitoring Blocks (experimental)
One or more blocks could be defined to contain network statistics or
traffic monitoring information. They could be use to store data
collected from RMON or Netflow probes, or from other network
monitoring tools.
3.8. Event/Security Block (experimental)
This block could be used to store events. Events could contain
generic information (for example network load over 50%, server
down...) or security alerts. An event could be:
* skipped, if the application doesn't know how to do with it
* processed independently by the packets. In other words, the
applications skips the packets and processes only the alerts
* processed in relation to packets: for example, a security tool
could load only the packets of the file that are near a security
alert; a monitoring tool could skip the packets captured while the
server was down.
4. Security Considerations
TBD.
Tuexen, et al. Expires 7 April 2022 [Page 7]
Internet-Draft pcapng October 2021
5. IANA Considerations
TBD.
[Open issue: decide whether the block types, option types, NRB Record
types, etc. should be IANA registries. And if so, what the IANA
policy for each should be (see RFC 5226)]
6. Contributors
Loris Degioanni and Gianluca Varenni were coauthoring this document
before it was submitted to the IETF.
7. Acknowledgments
The authors wish to thank Anders Broman, Ulf Lamping, Richard Sharpe
and many others for their invaluable comments.
8. References
8.1. Normative References
[I-D.tuexen-opsawg-pcapng]
Tuexen, M., Risso, F., Bongertz, J., Combs, G., Harris,
G., Chaudron, E., and M. C. Richardson, "PCAP Next
Generation (pcapng) Capture File Format", Work in
Progress, Internet-Draft, draft-tuexen-opsawg-pcapng-03,
23 June 2021, <https://www.ietf.org/archive/id/draft-
tuexen-opsawg-pcapng-03.txt>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
8.2. Informative References
[LINKTYPES]
The Tcpdump Group, "the tcpdump.org link-layer header
types registry", <http://www.tcpdump.org/linktypes.html>.
Authors' Addresses
Tuexen, et al. Expires 7 April 2022 [Page 8]
Internet-Draft pcapng October 2021
Michael Tuexen (editor)
Muenster University of Applied Sciences
Stegerwaldstrasse 39
48565 Steinfurt
Germany
Email: tuexen@fh-muenster.de
Fulvio Risso
Politecnico di Torino
Corso Duca degli Abruzzi, 24
10129 Torino
Italy
Email: fulvio.risso@polito.it
Jasper Bongertz
Airbus Defence and Space CyberSecurity
Kanzlei 63c
40667 Meerbusch
Germany
Email: jasper@packet-foo.com
Gerald Combs
Wireshark Foundation
339 Madson Pl
Davis, CA 95618
United States of America
Email: gerald@wireshark.org
Guy Harris
Email: gharris@sonic.net
Eelco Chaudron
Red Hat
De Entree 238
1101 EE Amsterdam
Netherlands
Email: eelco@redhat.com
Tuexen, et al. Expires 7 April 2022 [Page 9]
Internet-Draft pcapng October 2021
Michael C. Richardson
Sandelman Software Works
Email: mcr+ietf@sandelman.ca
URI: http://www.sandelman.ca/
Tuexen, et al. Expires 7 April 2022 [Page 10]