Tools for the people who keep the lights on
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Subnet calculator
CIDR to network, broadcast, usable hosts, wildcard mask and range.
- Network
- 192.168.10.0
- Broadcast
- 192.168.10.255
- First host
- 192.168.10.1
- Last host
- 192.168.10.254
- Usable hosts
- 254
- Subnet mask
- 255.255.255.0
- Wildcard mask
- 0.0.0.255
- Class
- C · RFC1918 private
- Binary
- 11111111.11111111.11111111.00000000
DNS lookup
A, AAAA, MX, TXT, NS, CNAME records via DNS-over-HTTPS.
Email security checker
SPF, DMARC and DKIM posture of any domain with plain-English advice.
Password generator & strength
Cryptographically random passwords and passphrases, with entropy score.
Time to crack (offline, 10 billion guesses per second): 1.8e+20 years
SLA downtime calculator
What 99.9% really means in minutes per month, per year.
Allowed downtime
- Per day
- 1.4 min
- Per week
- 10.1 min
- Per month
- 43.8 min
- Per year
- 8.77 h
My IP & connection
Your public IP, ISP and location, plus IPv6 support.
Detecting your public address...
Managed IT plan estimator
Devices and needs in, recommended plan out.
Best for companies with 50 or fewer devices · 9/6 coverage
View plan detailsSecurity posture score
Ten questions, one score and a prioritised fix list.
0/10
Port & protocol reference
Search 100+ common TCP/UDP ports and what they do.
| Port | Protocol | Service | Description |
|---|---|---|---|
| 20 | TCP | FTP data | File transfer (data channel) |
| 21 | TCP | FTP | File transfer control. Avoid, use SFTP |
| 22 | TCP | SSH / SFTP | Secure shell, secure file transfer |
| 23 | TCP | Telnet | Insecure remote login. Disable |
| 25 | TCP | SMTP | Mail transfer between servers |
| 53 | TCP/UDP | DNS | Domain name resolution |
| 67 | UDP | DHCP server | Dynamic IP assignment |
| 68 | UDP | DHCP client | Dynamic IP assignment |
| 69 | UDP | TFTP | Trivial file transfer (firmware, PXE) |
| 80 | TCP | HTTP | Web, unencrypted |
| 88 | TCP/UDP | Kerberos | Active Directory authentication |
| 110 | TCP | POP3 | Mail retrieval (legacy) |
| 123 | UDP | NTP | Time synchronisation |
| 135 | TCP | MS RPC | Windows RPC endpoint mapper |
| 137 | UDP | NetBIOS name | Windows name service |
| 139 | TCP | NetBIOS session | Legacy SMB over NetBIOS |
| 143 | TCP | IMAP | Mail retrieval |
| 161 | UDP | SNMP | Network monitoring |
| 162 | UDP | SNMP trap | Monitoring alerts |
| 389 | TCP/UDP | LDAP | Directory services |
| 443 | TCP | HTTPS | Web, TLS encrypted |
| 445 | TCP | SMB | Windows file sharing. Never expose to the internet |
| 465 | TCP | SMTPS | Mail submission over TLS |
| 500 | UDP | IKE / IPsec | VPN key exchange |
| 514 | UDP | Syslog | Log forwarding |
| 554 | TCP | RTSP | Camera video streams |
| 587 | TCP | SMTP submission | Mail submission (STARTTLS) |
| 636 | TCP | LDAPS | Directory over TLS |
| 853 | TCP | DNS over TLS | Encrypted DNS |
| 873 | TCP | rsync | File synchronisation |
| 902 | TCP | VMware ESXi | Host management |
| 993 | TCP | IMAPS | Mail retrieval over TLS |
| 995 | TCP | POP3S | POP over TLS |
| 1194 | UDP | OpenVPN | VPN |
| 1433 | TCP | MS SQL | Microsoft SQL Server |
| 1521 | TCP | Oracle DB | Oracle listener |
| 1701 | UDP | L2TP | VPN tunnelling |
| 1723 | TCP | PPTP | Legacy VPN. Insecure |
| 1812 | UDP | RADIUS | Network authentication (Wi-Fi 802.1X) |
| 1883 | TCP | MQTT | IoT messaging |
Data size converter
Bits, bytes, KB, MB, GB, TB, PB - binary and decimal.
- bits
- 8,000,000,000
- B
- 1,000,000,000
- KB
- 1,000,000
- MB
- 1,000
- GB
- 1
- TB
- 0.001
- PB
- 0.000001
These tools are provided free of charge for convenience and education. Results are indicative only; validate before making production changes.
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