IPv4 Wildcard Mask & Cisco ACL Calculator
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Convert subnet masks to Cisco wildcard masks (inverse masks) and generate access control list (ACL) network rule statements.
Network & Prefix Input
Wildcard & IOS Statements
Wildcard (Inverse) Mask
0.0.0.255
Subnet Mask
255.255.255.0
Cisco Standard ACL Rule:
access-list 10 permit 192.168.10.0 0.0.0.255
Cisco OSPF Network Statement:
network 192.168.10.0 0.0.0.255 area 0
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Direct In-Browser Handoff
IP Subnetting & Addressing Pipeline
Chain this tool with complementary private browser utilities for a complete zero-server workflow:
Helpful Examples
Class C /24 Subnet
IP: 192.168.1.0, Mask: 255.255.255.0
192.168.1.0 /24How to Use the IPv4 Wildcard Mask & Cisco ACL Calculator
Client-side Cisco wildcard mask and access control list calculator. Inverts 32-bit subnet masks into bitwise wildcard masks (255.255.255.255 minus subnet mask) used in Cisco IOS, OSPF, EIGRP, and BGP routing access control filters.
Privacy & Data Processing Notice
No user data leaves your browser. Computation is executed entirely on your device. We do not store, view, or transmit your inputs over our network. Your computation remains on your personal machine.
Frequently Asked Questions
What is a wildcard mask?
A wildcard mask (inverse mask) indicates which bits of an IP address must match. A bit 0 means the corresponding bit must match exactly; a bit 1 means the bit can be ignored (wildcard). It is the bitwise complement of the subnet mask.
How do you calculate a wildcard mask?
Subtract each octet of the subnet mask from 255. For example, for 255.255.255.0: 255-255 = 0, 255-255 = 0, 255-255 = 0, 255-0 = 255, giving 0.0.0.255.
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