Rohde & Schwarz GP-E - Using Anchors in String Decoders

Application Examples
R&S
®
GP-E/GP-S
204User Manual v16.2.1 ─ 01
Field Setting
"Type"
string
"Left Anchor"
any
"Right Anchor"
any
"Expression" [keyword]
4.13.6 Using Anchors in String Decoders
Protocol decoders that use the string type can use anchors to define which part of
the expression to search for keywords.
Consider a decoder created with the following settings to match traffic if the requested
resource (URI) contains the expression used.
Table 4-6: Sample decoder settings to match URIs.
Field Setting
"Protocol"
http
"Option"
requestURI
"Type"
string
"Expression"
used
When searching in the Request URI, remember that the URI begins with the trailing
slash that follows the host name. The host name (www.amazon.com in the examples
below) is not part of the requested resource.
A decoder with the settings shown above would match traffic as follows, depending on
the anchor settings and the visited URLs.
●
Case 1:
– Left anchor: string
– Right anchor: any
– Visited URL: www.amazon.com/books-used-books-textbooks
No match, because the string does not appear at the beginning of the content
(URI)
●
Case 2:
– Left anchor: word
– Right anchor: any
– Visited URL: www.amazon.com/books-used-books-textbooks
Matches, because the expression used appears as a single word
●
Case 3:
– Left anchor: word
Decoder Examples