Network & SysAdmin
IPv4 CIDR subnet calculators, network diagnostics, and system administrator utilities.
Available Tools (45)
← Back to all toolsIP & Subnet Calculation
IPv4 Subnet Calculator
Calculate IPv4 network, mask, broadcast, host range and address counts for prefixes /0 through /32, including /31 point-to-point links.
IPv6 Subnet & Prefix Calculator
Calculates the normalized IPv6 network, first and last address, and exact decimal address count for one address and prefix.
IPv4 to Mapped IPv6 & Hex Converter
IPv4 / IPv6 transition formats. Enter dotted IPv4 (optional /0–/32, validated only) or an IPv4-mapped IPv6 address such as ::ffff:192.0.2.1 or ::ffff:c000:201. IPv6 input must have no suffix. General IPv6, 6to4 input and zone identifiers are rejected.
IP Range to CIDR Calculator
Converts an inclusive IPv4 start–end range into the smallest exact set of aligned CIDR blocks, without filling gaps outside the range.
IPv4 CIDR Range Summary
Enter one dotted IPv4 address with optional /0–/32 (default /24). Run locally to normalize the CIDR and show network, upper boundary and host count. For blocks of at most 4096 addresses, read and copy the host list.
Private IP & Bogon Address Checker
Check IPv4 or IPv6 against a dated local snapshot of the complete IANA special-purpose registries, with flags, source and longest-prefix matches.
Subnet Mask to Wildcard Mask (Cisco)
Convert CIDR, subnet masks and wildcard masks; inspect bit inversions and an illustrative Cisco ACL.
Route Summarization / CIDR Aggregation
Summarize up to 100 IPv4 CIDRs, calculate entry savings and exact address coverage, and warn about extra coverage and blackhole risk.
IPv6 Subnet & Prefix Allocation Planner
Plan IPv6 subnet depth with exact BigInt capacity, compressed and full first/last addresses, a 128-bit split diagram and bounded pages.
IPv4 Representation Converter
Convert dotted IPv4, unsigned decimal, hexadecimal and binary representations locally, with four explicit 8-bit groups.
Tool category
DNS WireFormat Hex Packet Parser
Decode DNS header fields, compressed names and A, AAAA, CNAME, MX and TXT records from hexadecimal bytes locally.
Offline HAR Network Waterfall Analyzer
Summarizes HAR request totals, body bytes, slowest entries and HTTP errors; no timing-phase waterfall.
DNS TTL Remaining-Time Calculator
It accepts a fully qualified domain name and, optionally, a JSON object with domain, ttlSeconds or ttl, and elapsedSeconds or elapsed. It returns the trimmed domain, the two numeric inputs, remainingSeconds as max(0, TTL minus elapsed), and cacheExpiryProgressPercent rounded to two decimal places.
MAC Address OUI Vendor Lookup
Look up MAC address block assignments in a dated offline IEEE registry snapshot, normalize three formats, or generate a local unicast address.
Network MTU & MSS Overhead Calculator
Calculate fixed-header MSS or model PPPoE, basic GRE and WireGuard with per-layer byte budgets.
SDP Media Sections and Codec Inspector
Inspect SDP media sections, inherited connection and ICE fields, ordered codecs, fmtp parameters and parsed ICE candidates locally.
Wireshark Display Filter Builder
Build local display filters for IP, ports, TCP flags, HTTP status and DNS names, with logic and presets.
DNS Amplification Estimate and Defense Guide
Estimate DNS response/request byte ratios for ANY, TXT, DNSKEY or A and review BCP 38, recursive access controls and response rate limiting.
Ethernet Frame & 802.1Q VLAN Inspector
Inspect Ethernet MAC addresses, EtherType and one VLAN tag with byte offsets, PCP/DEI/VID fields and a trunk explanation.
TCP Handshake & State Machine Visualizer
Step through a normal TCP active open and close with two endpoint states, segment direction, sequence numbers, acknowledgments and TIME-WAIT.
Ping Transcript and TTL Estimates
Parse pasted English ping replies and summaries locally, showing RTT ranges, loss and conditional TTL hop estimates.
Traceroute Hop Cards
Turn pasted Linux traceroute or Windows tracert text into hop cards with RTT bounds, unanswered probes and cautious latency-rise markers.
Tool category
IANA offline port directory
Search the bundled IANA registry by port number or service name, filter TCP/UDP/SCTP/DCCP, and review registered uses and local hardening guidance.
URL Parser & Query Param Visualizer
Inspect URL components, edit ordered duplicate query pairs, group bracket-array names, remove selected tracking parameters and rebuild a URL locally.
cURL Request Form and Flag Dictionary
Build an HTTP(S) cURL command from method, URL, headers, body, proxy and timeout, then inspect 31 common flags.
HTTP Method Scenario Guide
Choose among nine business scenarios for an HTTP method recommendation, safety, idempotency, caching and retry boundaries.
Open Graph and Twitter Card Live Preview
Generate Open Graph and Twitter summary_large_image tags from a form with site name, and preview a large card locally.
Browser API, WebGL and WASM Capability Probes
Inspect WebGL texture limits, renderer and extensions, P3, API exposure, touch points and WebAssembly shared-memory prerequisites locally.
Transfer Units, Time and 10% Overhead
Convert MB/GB and Mbps/MB/s, calculate theoretical and 10%-overhead transfer times, and compare six bandwidth tiers locally.
Offline ASN Directory and BGP Path Guide
Search three sourced ASN organization records locally, distinguish 16-bit and 32-bit numbers and learn special-purpose ranges and BGP path policy.
IANA Offline TLD Directory
Search an offline IANA root-zone snapshot by suffix or registry manager, with official types, Unicode labels and dated delegation-list membership.
WHOIS Registration Guide
Prepare official domain lookup links and read five registration fields, ten EPP status explanations, privacy notes and browser limits.
PEM Certificate Chain Organizer
Inspect pasted PEM certificate names, find structural issuer gaps and export a candidate server certificate order locally.
Cache Policy Presets and Templates
Choose a resource policy, compare Cache-Control directives and prepare response headers or static Cloudflare Pages and Netlify templates.
HTTP Protocol Interactive Explainer
Compare HTTP/1.1, HTTP/2 and HTTP/3 with a local stream animation, a header dictionary illustration and qualified connection explanations.
WebSocket Heartbeat and Retry Template
Generate a local JavaScript heartbeat template with missed-reply limits, capped exponential reconnect delays and full jitter.
Exact Data Amount Converter
Convert data amounts across decimal and binary byte units with exact decimal and scientific notation; keep the rate calculator below.
HTTP Redirect Scenario Guide
Choose a redirect scenario and request method; compare local illustrations of 301, 302, 303, 307 and 308 without sending a request.
DNS CAA Policy Builder
Select certificate authorities and an optional reporting email to generate local issue, issuewild and iodef DNS record text.
Tool category
SSH Config and Connection Command
Generate an SSH Host block with a keepalive interval, optional ProxyJump and a matching connection command locally.
Systemd Service and Resource Configuration
Create systemd service text with environment variables, restart policy, journal logging, resource limits and startup commands.
Nginx Proxy, CORS and Static Cache Builder
Create a local Nginx proxy snippet with optional gzip, fixed-origin CORS and caching for files served from a static root.
Apache Rewrite Conditions to Nginx
Convert a bounded document-root Apache rewrite subset to Nginx with associated conditions, query-string handling and explicit unsupported-rule diagnostics.
Syslog Header and Structured Data Inspector
Inspect one RFC 5424 VERSION 1 message, calendar timestamps and structured data with highlighted syntax diagnostics.
SNMP OID Tree and Typed Reference
Browse 16 core SNMP objects with MIB paths, data types and collection notes, including interfaces and host resources.