KFL2 Complete Variable and Field Reference

This is the exhaustive reference for every variable available in KFL2 filters. KFL2 is built on Google's CEL (Common Expression Language) and evaluates against Kubeshark's protobuf-based BaseEntry structure.

Most Commonly Used Variables

These are the variables you'll reach for in 90% of investigations:

Variable	Type	What it's for
status_code	int	HTTP response status (200, 404, 500)
method	string	HTTP method (GET, POST, PUT, DELETE)
path	string	URL path without query string
dst.pod.namespace	string	Where traffic is going (namespace)
dst.service.name	string	Where traffic is going (service)
src.pod.name	string	Where traffic comes from (pod)
elapsed_time	int	Request duration in microseconds
dns_questions	[]string	DNS domains being queried
namespaces	[]string	All namespaces involved (src + dst)

Network-Level Variables

Variable	Type	Description	Example
src.ip	string	Source IP address	"10.0.53.101"
dst.ip	string	Destination IP address	"192.168.1.1"
src.port	int	Source port number	43210
dst.port	int	Destination port number	8080
protocol	string	Detected protocol type	"HTTP", "DNS"

Identity and Metadata Variables

Variable	Type	Description
id	int	BaseEntry unique identifier (assigned by sniffer)
node_id	string	Node identifier (assigned by hub)
index	int	Entry index for stream uniqueness
stream	string	Stream identifier (hex string)
timestamp	timestamp	Event time (UTC), use with timestamp() function
elapsed_time	int	Age since timestamp in microseconds
worker	string	Worker identifier

Cross-Reference Variables

Variable	Type	Description
conn_id	int	L7 to L4 connection cross-reference ID
flow_id	int	L7 to L4 flow cross-reference ID
has_pcap	bool	Whether PCAP data is available for this entry

Capture Source Variables

Variable	Type	Description	Values
capture_source	string	Canonical capture source	"unspecified", "af_packet", "ebpf", "ebpf_tls"
capture_backend	string	Backend family	"af_packet", "ebpf"
capture_source_code	int	Numeric enum	0=unspecified, 1=af_packet, 2=ebpf, 3=ebpf_tls
capture	map	Nested map access	capture["source"], capture["backend"]

Protocol Detection Flags

Boolean variables indicating detected protocol. Use as first filter term for performance.

Variable	Protocol	Variable	Protocol
http	HTTP/1.1, HTTP/2	redis	Redis
dns	DNS	kafka	Kafka
tls	TLS/SSL handshake	amqp	AMQP messaging
tcp	TCP transport	ldap	LDAP directory
udp	UDP transport	ws	WebSocket
sctp	SCTP streaming	gql	GraphQL (v1 or v2)
icmp	ICMP	gqlv1	GraphQL v1 only
radius	RADIUS auth	gqlv2	GraphQL v2 only
diameter	Diameter	conn	L4 connection tracking
flow	L4 flow tracking	tcp_conn	TCP connection tracking
tcp_flow	TCP flow tracking	udp_conn	UDP connection tracking
udp_flow	UDP flow tracking

HTTP Variables

Variable	Type	Description	Example
method	string	HTTP method	"GET", "POST", "PUT", "DELETE", "PATCH"
url	string	Full URL path and query string	"/api/users?id=123"
path	string	URL path component (no query)	"/api/users"
status_code	int	HTTP response status code	200, 404, 500
http_version	string	HTTP protocol version	"HTTP/1.1", "HTTP/2"
query_string	map[string]string	Parsed URL query parameters	query_string["id"] → "123"
request.headers	map[string]string	Request HTTP headers	request.headers["content-type"]
response.headers	map[string]string	Response HTTP headers	response.headers["server"]
request.cookies	map[string]string	Request cookies	request.cookies["session"]
response.cookies	map[string]string	Response cookies	response.cookies["token"]
request_headers_size	int	Request headers size in bytes
request_body_size	int	Request body size in bytes
response_headers_size	int	Response headers size in bytes
response_body_size	int	Response body size in bytes

GraphQL requests have gql (or gqlv1/gqlv2) set to true and all HTTP variables available.

Example: http && method == "POST" && status_code >= 500 && path.contains("/api")

DNS Variables

Variable	Type	Description	Example
dns_questions	[]string	Question domain names (request + response)	["example.com"]
dns_answers	[]string	Answer domain names	["1.2.3.4"]
dns_question_types	[]string	Record types in questions	["A"], ["AAAA"], ["CNAME"]
dns_request	bool	Is DNS request message
dns_response	bool	Is DNS response message
dns_request_length	int	DNS request size in bytes (0 if absent)
dns_response_length	int	DNS response size in bytes (0 if absent)
dns_total_size	int	Sum of request + response sizes

Supported question types: A, AAAA, NS, CNAME, SOA, MX, TXT, SRV, PTR, ANY.

Example: dns && dns_response && status_code != 0 (failed DNS lookups)

TLS Variables

Variable	Type	Description	Example
tls	bool	TLS payload detected
tls_summary	string	TLS handshake summary	"ClientHello", "ServerHello"
tls_info	string	TLS connection details	"TLS 1.3, AES-256-GCM"
tls_request_size	int	TLS request size in bytes
tls_response_size	int	TLS response size in bytes
tls_total_size	int	Sum of request + response (computed if not provided)

TCP Variables

Variable	Type	Description
tcp	bool	TCP payload detected
tcp_method	string	TCP method information
tcp_payload	bytes	Raw TCP payload data
tcp_error_type	string	TCP error type (empty if none)
tcp_error_message	string	TCP error message (empty if none)

UDP Variables

Variable	Type	Description
udp	bool	UDP payload detected
udp_length	int	UDP packet length
udp_checksum	int	UDP checksum value
udp_payload	bytes	Raw UDP payload data

SCTP Variables

Variable	Type	Description
sctp	bool	SCTP payload detected
sctp_checksum	int	SCTP checksum value
sctp_chunk_type	string	SCTP chunk type
sctp_length	int	SCTP chunk length

ICMP Variables

Variable	Type	Description
icmp	bool	ICMP payload detected
icmp_type	string	ICMP type code
icmp_version	int	ICMP version (4 or 6)
icmp_length	int	ICMP message length

WebSocket Variables

Variable	Type	Description	Values
ws	bool	WebSocket payload detected
ws_opcode	string	WebSocket operation code	"text", "binary", "close", "ping", "pong"
ws_request	bool	Is WebSocket request
ws_response	bool	Is WebSocket response
ws_request_payload_data	string	Request payload (safely truncated)
ws_request_payload_length	int	Request payload length in bytes
ws_response_payload_length	int	Response payload length in bytes

Redis Variables

Variable	Type	Description	Example
redis	bool	Redis payload detected
redis_type	string	Redis command verb	"GET", "SET", "DEL", "HGET"
redis_command	string	Full Redis command line	"GET session:1234"
redis_key	string	Key (truncated to 64 bytes)	"session:1234"
redis_request_size	int	Request size (0 if absent)
redis_response_size	int	Response size (0 if absent)
redis_total_size	int	Sum of request + response

Example: redis && redis_type == "GET" && redis_key.startsWith("session:")

Kafka Variables

Variable	Type	Description	Example
kafka	bool	Kafka payload detected
kafka_api_key	int	Kafka API key number	0=FETCH, 1=PRODUCE
kafka_api_key_name	string	Human-readable API operation	"PRODUCE", "FETCH"
kafka_client_id	string	Kafka client identifier	"payment-processor"
kafka_size	int	Message size (request preferred, else response)
kafka_request	bool	Is Kafka request
kafka_response	bool	Is Kafka response
kafka_request_summary	string	Request summary/topic	"orders-topic"
kafka_request_size	int	Request size (0 if absent)
kafka_response_size	int	Response size (0 if absent)

Example: kafka && kafka_api_key_name == "PRODUCE" && kafka_request_summary.contains("orders")

AMQP Variables

Variable	Type	Description	Example
amqp	bool	AMQP payload detected
amqp_method	string	AMQP method name	"basic.publish", "channel.open"
amqp_summary	string	Operation summary
amqp_request	bool	Is AMQP request
amqp_response	bool	Is AMQP response
amqp_request_length	int	Request length (0 if absent)
amqp_response_length	int	Response length (0 if absent)
amqp_total_size	int	Sum of request + response

LDAP Variables

Variable	Type	Description
ldap	bool	LDAP payload detected
ldap_type	string	LDAP operation type (request preferred)
ldap_summary	string	Operation summary
ldap_request	bool	Is LDAP request
ldap_response	bool	Is LDAP response
ldap_request_length	int	Request length (0 if absent)
ldap_response_length	int	Response length (0 if absent)
ldap_total_size	int	Sum of request + response

RADIUS Variables

Variable	Type	Description	Example
radius	bool	RADIUS payload detected
radius_code	int	RADIUS code (request preferred)
radius_code_name	string	Code name	"Access-Request"
radius_request	bool	Is RADIUS request
radius_response	bool	Is RADIUS response
radius_request_authenticator	string	Request authenticator (hex)
radius_request_length	int	Request size (0 if absent)
radius_response_length	int	Response size (0 if absent)
radius_total_size	int	Sum of request + response

Diameter Variables

Variable	Type	Description
diameter	bool	Diameter payload detected
diameter_method	string	Method name (request preferred)
diameter_summary	string	Operation summary
diameter_request	bool	Is Diameter request
diameter_response	bool	Is Diameter response
diameter_request_length	int	Request size (0 if absent)
diameter_response_length	int	Response size (0 if absent)
diameter_total_size	int	Sum of request + response

L4 Connection Tracking Variables

Variable	Type	Description	Example
conn	bool	Connection tracking entry
conn_state	string	Connection state	"open", "in_progress", "closed"
conn_local_pkts	int	Packets from local peer
conn_local_bytes	int	Bytes from local peer
conn_remote_pkts	int	Packets from remote peer
conn_remote_bytes	int	Bytes from remote peer
conn_l7_detected	[]string	L7 protocols detected on connection	["HTTP", "TLS"]
conn_group_id	int	Connection group identifier

Example: conn && conn_state == "open" && conn_local_bytes > 1000000 (high-volume open connections)

L4 Flow Tracking Variables

Flows extend connections with rate metrics (packets/bytes per second).

Variable	Type	Description
flow	bool	Flow tracking entry
flow_state	string	Flow state ("open", "in_progress", "closed")
flow_local_pkts	int	Packets from local peer
flow_local_bytes	int	Bytes from local peer
flow_remote_pkts	int	Packets from remote peer
flow_remote_bytes	int	Bytes from remote peer
flow_local_pps	int	Local packets per second
flow_local_bps	int	Local bytes per second
flow_remote_pps	int	Remote packets per second
flow_remote_bps	int	Remote bytes per second
flow_l7_detected	[]string	L7 protocols detected on flow
flow_group_id	int	Flow group identifier

Example: tcp_flow && flow_local_bps > 5000000 (high-bandwidth TCP flows)

Kubernetes Variables

Pod and Service (Directional)

Variable	Type	Description
src.pod.name	string	Source pod name
src.pod.namespace	string	Source pod namespace
dst.pod.name	string	Destination pod name
dst.pod.namespace	string	Destination pod namespace
src.service.name	string	Source service name
src.service.namespace	string	Source service namespace
dst.service.name	string	Destination service name
dst.service.namespace	string	Destination service namespace

Fallback behavior: Pod namespace/name fields automatically fall back to service data when pod info is unavailable. This means dst.pod.namespace works even when only service-level resolution exists.

Example: src.service.name == "api-gateway" && dst.pod.namespace == "production"

Aggregate Collections (Non-Directional)

Variable	Type	Description
namespaces	[]string	All namespaces (src + dst, pod + service)
pods	[]string	All pod names (src + dst)
services	[]string	All service names (src + dst)

Labels and Annotations

Variable	Type	Description
local_labels	map[string]string	Kubernetes labels of local peer
local_annotations	map[string]string	Kubernetes annotations of local peer
remote_labels	map[string]string	Kubernetes labels of remote peer
remote_annotations	map[string]string	Kubernetes annotations of remote peer

Use map_get(local_labels, "key", "default") for safe access that won't error on missing keys.

Example: map_get(local_labels, "app", "") == "checkout" && "production" in namespaces

Node Information

Variable	Type	Description
node	map	Nested: node["name"], node["ip"]
node_name	string	Node name (flat alias)
node_ip	string	Node IP (flat alias)
local_node_name	string	Node name of local peer
remote_node_name	string	Node name of remote peer

Process Information

Variable	Type	Description
local_process_name	string	Process name on local peer
remote_process_name	string	Process name on remote peer

DNS Resolution

Variable	Type	Description
src.dns	string	DNS resolution of source IP
dst.dns	string	DNS resolution of destination IP
dns_resolutions	[]string	All DNS resolutions (deduplicated)

Resolution Status

Variable	Type	Values
local_resolution_status	string	"" (resolved), "no_node_mapping", "rpc_error", "rpc_empty", "cache_miss", "queue_full"
remote_resolution_status	string	Same as above

Default Values

When a variable is not present in an entry, KFL2 uses these defaults:

Type	Default
string	""
int	0
bool	false
list	[]
map	{}
bytes	[]

Protocol Variable Precedence

For protocols with request/response pairs (Kafka, RADIUS, Diameter), merged fields prefer the request side. If no request exists, the response value is used. Size totals are always computed as request_size + response_size.

CEL Language Features

KFL2 supports the full CEL specification:

• Short-circuit evaluation: && stops on first false, || stops on first true
• Ternary: condition ? value_if_true : value_if_false
• Regex: str.matches("pattern") uses RE2 syntax
• Type coercion: Timestamps require timestamp(), durations require duration()
• Null safety: Use in operator or map_get() before accessing map keys

For the full CEL specification, see the CEL Language Definition.