User Guide

Customizing Wireshark
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10.12. Object Identifiers
Many protocols that use ASN.1 use Object Identifiers (OIDs) to uniquely identify certain pieces of
information. In many cases, they are used in an extension mechanism so that new object identifiers (and
associated values) may be defined without needing to change the base standard.
Whilst Wireshark has knowledge about many of the OIDs and the syntax of their associated values, the
extensibility means that other values may be encountered.
Wireshark uses this table to allow the user to define the name and syntax of Object Identifiers that
Wireshark does not know about (for example, a privately defined X.400 extension). It also allows the user
to override the name and syntax of Object Identifiers that Wireshark does know about (e.g. changing the
name "id-at-countryName" to just "c").
This table is handled by an Section 10.7, “User Table” with the following fields.
OID The string representation of the Object Identifier e.g. "2.5.4.6".
Name The name that should be displayed by Wireshark when the Object Identifier is dissected e.g.
("c");
Syntax The syntax of the value associated with the Object Identifier. This must be one of the syntaxes
that Wireshark already knows about (e.g. "PrintableString").
10.13. PRES Users Context List
Wireshark uses this table to map a presentation context identifier to a given object identifier when the
capture does not contain a PRES package with a presentation context definition list for the conversation.
This table is handled by an Section 10.7, “User Table” with the following fields.
Context Id An Integer representing the presentation context identifier for which this
association is valid.
Syntax Name OID The object identifier representing the abstract syntax name, which defines the
protocol that is carried over this association.
10.14. SCCP users Table
Wireshark uses this table to map specific protocols to a certain DPC/SSN combination for SCCP.
This table is handled by an Section 10.7, “User Table” with the following fields.
Network Indicator An Integer representing the network indicator for which this association is
valid.
Called DPCs An range of integers representing the dpcs for which this association is valid.
Called SSNs An range of integers representing the ssns for which this association is valid.
User protocol The protocol that is carried over this association