Astro

Encapsulation Packet Protocol operations: encode, decode, inspect, validate, and stream CCSDS Encapsulation Packets (CCSDS 133.1-B-3).

Subcommands

Command	Description
`astro epp decode`	Decode raw bytes into Encapsulation Packet fields
`astro epp encode`	Construct an Encapsulation Packet from header fields and data zone
`astro epp inspect`	Pretty-print an annotated packet breakdown with hex dump
`astro epp validate`	Check PVN, Protocol ID, header format, and packet length consistency
`astro epp stream`	Decode a stream of concatenated Encapsulation Packets
`astro epp gen`	Generate synthetic Encapsulation Packets

Common flags

All subcommands that read input support:

Flag	Default	Description
`--input`	`hex`	Input format: `hex` (hex-encoded text) or `bin` (raw binary)

All subcommands that produce output support:

Flag	Default	Description
`--format`	varies	Output format: `text`, `json`, or `hex`

Input can be provided as a file argument or piped via stdin. Hex input accepts optional 0x prefix, spaces, and newlines.

astro epp decode

Decode an Encapsulation Packet from raw bytes, printing its header fields and data zone.

astro epp decode [file] [flags]

Flags

Flag	Default	Description
`--input`	`hex`	Input format: `hex` or `bin`
`--format`	`text`	Output format: `text`, `json`, or `hex`

Examples

# Decode hex from stdin
echo "e90661626364" | astro epp decode --input hex

# Decode with JSON output
echo "e90661626364" | astro epp decode --input hex --format json

# Decode a binary file
astro epp decode --input bin packet.bin

astro epp encode

Construct an Encapsulation Packet from header fields and hex-encoded data zone.

astro epp encode [flags]

Flags

Flag	Default	Description
`--pid`	`2`	Protocol ID (0=idle, 1=LTP, 2=IPE, 6=extended, 7=mission)
`--data`		Data zone as hex string (omit for the 1-octet idle packet)
`--long-length`	`false`	Force at least a 4-octet header (2-octet length field)
`--user-defined`	`0`	User Defined Field value, 4 bits (4- and 8-octet headers)
`--ext-pid`	`0`	Protocol ID Extension, 4 bits (4- and 8-octet headers)
`--ccsds-defined`	`0`	CCSDS Defined Field value (8-octet header)
`--format`	`hex`	Output format: `text`, `json`, or `hex`

Examples

# Encode an IPE packet
astro epp encode --pid 2 --data 4500001400

# Encode a mission-specific packet with a user defined field value
astro epp encode --pid 7 --data a1b2c3d4 --user-defined 5

# Encode with an extended protocol ID (4-octet header)
astro epp encode --pid 6 --ext-pid 9 --data a1b2c3d4

# Encode with a CCSDS-defined field (8-octet header)
astro epp encode --pid 6 --ext-pid 9 --ccsds-defined 4660 --data a1b2c3d4

# Encode the 1-octet idle packet (0xE0)
astro epp encode --pid 0

# Encode with JSON output
astro epp encode --pid 2 --data 61626364 --format json

astro epp inspect

Display an annotated breakdown of an Encapsulation Packet showing header fields, data zone, and a hex dump.

astro epp inspect [file] [flags]

Flags

Flag	Default	Description
`--input`	`hex`	Input format: `hex` or `bin`

Examples

# Inspect from hex stdin
echo "e90661626364" | astro epp inspect --input hex

# Inspect binary file
astro epp inspect --input bin packet.bin

Sample Output

Encapsulation Packet Inspector
────────────────────────────────────────────────────────────
Header (2 bytes, LoL 1)
  PVN .................. 7
  Protocol ID .......... 2 (ipe)
  Length of Length ...... 1
  Packet Length ........ 6 (total packet: 6 bytes)
────────────────────────────────────────────────────────────
Data Zone (4 bytes)
  0000  61 62 63 64                                       |abcd|
────────────────────────────────────────────────────────────
Raw Packet (6 bytes)
  0000  e9 06 61 62 63 64                                 |..abcd|

astro epp validate

Validate an Encapsulation Packet for CCSDS conformance: checks PVN, Protocol ID, header format, and packet length consistency.

astro epp validate [file] [flags]

Flags

Flag	Default	Description
`--input`	`hex`	Input format: `hex` or `bin`

Examples

# Validate a packet
echo "e90661626364" | astro epp validate --input hex

# Validate a binary file
astro epp validate --input bin packet.bin

# Encode then validate
astro epp encode --pid 2 --data a1b2c3d4 | astro epp validate --input hex

astro epp stream

Decode a stream of concatenated Encapsulation Packets, printing each packet as it is parsed. Useful for processing capture files containing multiple back-to-back packets.

astro epp stream [file] [flags]

Flags

Flag	Default	Description
`--input`	`hex`	Input format: `hex` or `bin`
`--format`	`text`	Output format: `text`, `json`, or `hex`

With --format json, each packet is printed as a single JSON line (NDJSON), suitable for piping to jq or other tools.

Examples

# Stream decode a binary capture
astro epp stream --input bin capture.bin

# Stream decode with JSON output for jq processing
astro epp stream --input bin capture.bin --format json | jq '.protocol_id'

# Concatenate multiple encoded packets and stream decode
P1=$(astro epp encode --pid 2 --data aabb)
P2=$(astro epp encode --pid 7 --data ccdd)
echo "${P1}${P2}" | astro epp stream --input hex

astro epp gen

Generate a stream of synthetic Encapsulation Packets with random data zones.

astro epp gen [flags]

Flags

Flag	Default	Description
`--pid`	`2`	Protocol ID (1=LTP, 2=IPE, 7=mission)
`--count`	`10`	Number of packets to generate
`--size`	`64`	Data zone size in bytes per packet
`--long-length`	`false`	Force at least a 4-octet header (2-octet length field)
`--format`	`bin`	Output format: `bin` or `hex`

Examples

# Generate 10 IPE packets of 64 bytes each
astro epp gen --pid 2 --count 10 --size 64

# Generate and pipe to stream decoder
astro epp gen --pid 2 --count 50 --size 128 --format bin | astro epp stream --input bin

# Generate mission-specific packets with long headers
astro epp gen --pid 7 --count 5 --size 32 --long-length --format hex

Piping

All commands support stdin/stdout piping for composability:

# Encode -> Inspect
astro epp encode --pid 2 --data 0102030405 | astro epp inspect --input hex

# Encode -> Validate
astro epp encode --pid 7 --data a1b2c3d4 | astro epp validate --input hex

# Encode -> Decode as JSON
astro epp encode --pid 2 --data 0102030405 | astro epp decode --input hex --format json

# Generate -> Stream decode
astro epp gen --pid 2 --count 20 --size 32 --format bin | astro epp stream --input bin

# EPP -> SPP interop: EPP carrying SPP-encoded data
SPP=$(astro spp encode --apid 100 --type tm --data 61626364)
astro epp encode --pid 7 --data $SPP

See also: the protocol page for the standard and the Go API, and the conformance statement for what is and is not implemented.