Filter determines whether a packet satisfies specified condition. Actually Filter is wrapper for bpf_program. For details of filter expression, see tcpdump(1).

Super Class:


Class Methods:

compile(expr, capture[, optimize[, netmask]])
new(expr, capture[, optimize[, netmask]])

Create a new Filter object. expr is a filter string. capture is a Capture object. optimize controls optimization of resulting code. netmask specifies the netmask of the local net.

Created Filter can be applied to packets captured via capture.

If libpcap-0.5 or later used, one of following values can be specified instead of capture:

[snaplen, datalink]
an array containing required parameters
omitted (or nil)
Ethernet default ([68, DLT_EN10MB])


self === packet
self =~ packet

Return true if packet matches this filter.

~ self

Return a Filter which represents "not self".

self | other

Return a Filter which represents "self or other".

self & other

Return a Filter which represents "self and other".


Returns the orginal string from which the filter is constructed.