output formats

Output formats

CIDR (default)

The default output is sorted, non-overlapping CIDR blocks:

10.0.0.0/24
10.0.1.0/25
10.0.1.128/26

This is the optimal representation — the fewest entries that cover the exact set of IPs.

Controlling CIDR prefixes

Minimum prefix — restrict the largest block size:

# Only /24 to /32 (no blocks larger than /24)
iprange --min-prefix 24 blocklist.txt

A /16 network would be expressed as 256 /24 entries. Warning: misuse can produce very large output.

Specific prefixes — allow only certain prefix lengths:

# Only /16, /24, and /32
iprange --prefixes 16,24,32 blocklist.txt

Prefix /32 is always enabled regardless of settings.

For IPv6, the same options work with prefix range 0-128.

Ranges (--print-ranges / -j)

Print start-end ranges:

10.0.0.0-10.0.0.255
10.0.1.0-10.0.1.191

Single IPs print as ranges with identical endpoints: 10.0.0.5-10.0.0.5

Single IPs (--print-single-ips / -1)

Enumerate every individual IP address:

10.0.0.0
10.0.0.1
10.0.0.2
...

Safety cap: ranges larger than 16,777,216 IPs (256^3) are skipped with a warning to stderr. This prevents unbounded output from large ranges like 0.0.0.0/0. The cap applies to both IPv4 and IPv6 modes.

Binary (--print-binary)

Machine-readable binary format for fast round-trips:

# Save
iprange --print-binary blocklist.txt > cache.bin

# Load
iprange cache.bin

Binary files include:

• A header line identifying the format version (v1.0 for IPv4, v2.0 for IPv6)
• Metadata: family, optimization flag, record count, unique IP count
• An endianness marker
• Raw address-pair records

Binary files are architecture-specific — they use native byte order and are intended as a same-machine cache. Do not transfer between machines with different endianness.

CSV output

CSV output is produced by the comparison and counting modes:

Mode	Columns
--compare	name1, name2, entries1, entries2, ips1, ips2, combined_ips, common_ips
--compare-first	name, entries, unique_ips, common_ips
--compare-next	name1, name2, entries1, entries2, ips1, ips2, combined_ips, common_ips
--count-unique	entries, unique_ips
--count-unique-all	name, entries, unique_ips

Add --header to print the column header as the first line.

Prefix and suffix strings

Customize output lines with arbitrary strings before and after each entry. This is useful for generating ipset restore commands, iptables rules, or other tool-specific formats.

Basic usage

# Add prefix to every line
iprange --print-prefix "add myset " blocklist.txt
# Output: add myset 10.0.0.0/24

# Add suffix to every line
iprange --print-suffix " timeout 3600" blocklist.txt
# Output: 10.0.0.0/24 timeout 3600

Separate handling for IPs and networks

Single IPs (/32 entries) and networks (other prefixes) can have different prefixes and suffixes. This is useful when single IPs and networks go into different ipsets:

iprange \
  --print-prefix-ips "add single-ips " \
  --print-prefix-nets "add networks " \
  blocklist.txt
# Output:
#   add networks 10.0.0.0/24
#   add single-ips 10.0.1.5

Option	Applies to
--print-prefix STRING	Both IPs and networks
--print-prefix-ips STRING	Single IPs only (/32)
--print-prefix-nets STRING	Networks only (not /32)
--print-suffix STRING	Both IPs and networks
--print-suffix-ips STRING	Single IPs only (/32)
--print-suffix-nets STRING	Networks only (not /32)

Quiet mode

Use --quiet with --diff to suppress output and only use the exit code:

iprange old.txt --diff new.txt --quiet
echo $?  # 0 = identical, 1 = different