fix(ns-scan): block network scan for large network (/19 or lower) #1493
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Tbaile
reviewed
Jan 29, 2026
packages/ns-api/files/ns.scan
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| def scan(device, interface): | ||
| ret = [] | ||
| u = EUci() | ||
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| if interface: | ||
| netmask = u.get('network', interface, 'netmask') | ||
| netmask_cidr = netmask_to_cidr_notation(netmask) | ||
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| # block arp-scan if the subnet is /19 or smaller | ||
| if netmask_cidr is not None and netmask_cidr < 20: | ||
| return utils.validation_error("subnet_too_large_for_scan") | ||
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gsanchietti
requested changes
Jan 30, 2026
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gsanchietti
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gsanchietti
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Since you're already executing the code in a try/except, you get rif of the netmask_to_cidr notation function
packages/ns-api/files/ns.scan
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| ret.append({"interface": i, "device": interfaces[i].get('device', '')}) | ||
| try: | ||
| netmask = u.get('network', i, 'netmask') or "" | ||
| netmask_cidr = netmask_to_cidr_notation(netmask) |
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Suggested change
| netmask_cidr = netmask_to_cidr_notation(netmask) | |
| netmask_cidr = ipaddress.IPv4Network(f'0.0.0.0/{netmask}').prefixlen |
packages/ns-api/files/ns.scan
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| def netmask_to_cidr_notation(netmask): | ||
| """Convert a netmask to CIDR notation (ex. 255.255.0.0 -> 16)""" | ||
| if not netmask: | ||
| return None | ||
| try: | ||
| return ipaddress.IPv4Network(f'0.0.0.0/{netmask}').prefixlen | ||
| except: | ||
| return None | ||
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Suggested change
| def netmask_to_cidr_notation(netmask): | |
| """Convert a netmask to CIDR notation (ex. 255.255.0.0 -> 16)""" | |
| if not netmask: | |
| return None | |
| try: | |
| return ipaddress.IPv4Network(f'0.0.0.0/{netmask}').prefixlen | |
| except: | |
| return None |
packages/ns-api/files/ns.scan
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| try: | ||
| interface = utils.get_interface_from_device(u, device) | ||
| netmask = u.get('network', interface, 'netmask') | ||
| netmask_cidr = netmask_to_cidr_notation(netmask) |
Member
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Suggested change
| netmask_cidr = netmask_to_cidr_notation(netmask) | |
| netmask_cidr = ipaddress.IPv4Network(f'0.0.0.0/{netmask}').prefixlen |
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This pull request enhances the network scanning functionality by adding subnet size validation and improving interface information. The most important changes are:
Network scanning improvements:
scanfunction to take bothdeviceandinterfaceparameters, and added logic to block ARP scans on subnets smaller than /20, returning a validation error if the subnet is too large.netmask_to_cidr_notationhelper function to convert a netmask (e.g., 255.255.0.0) into CIDR notation (e.g., 16), using theipaddressmodule.Interface listing enhancements:
list_interfacesfunction to include the netmask in CIDR notation for each interface in its output.Command-line interface updates:
interfaceparameter for scans, ensuring the new validation logic is used.Refs: #1434