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netconan - a Network Configuration Anonymizer


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Netconan (network configuration anonymizer) anonymizes text files that contain sensitive network information.

With Netconan, a sensitive input file

$ cat sensitive/cisco.cfg
! This is intentionet's sensitive comment
username admin password 7 122A001901
enable secret 5 $1$wtHI$0rN7R8PKwC30AsCGA77vy.
tacacs-server host key pwd1234
ip address
ip address 2001:2002::9d3b:1
route-map sea-to-lax ...
route-map sea-to-atl ...

can be anonymized

$ netconan -i sensitive -o anonymized \
    --sensitive-words intentionet,sea,lax,atl \
    --anonymize-passwords \
WARNING No salt was provided; using randomly generated "WNo5pX28MJOrqxfv"
INFO Anonymizing cisco.cfg

to produce an output file you can feel comfortable sharing.

$ cat anonymized/cisco.cfg
! This is db1792's sensitive comment
username admin password 7 09424B1D1A0A1913053E012724322D3765
enable secret 5 $1$0000$EhfXcDfB7iiakW6mwMy1i.
tacacs-server host key netconanRemoved2
ip address
ip address cd7e:83e:1eaf:2ada:7535:591e:6d47:a4b8
route-map e69ceb-to-880ac2 ...
route-map e69ceb-to-5d37ad ...

Installing Netconan

Install Netconan using pip:

$ pip install netconan


Netconan can anonymize many types of sensitive information:

  • Sensitive strings like passwords or SNMP community strings (--anonymize-passwords, -p), for many common network vendors.
  • IPv4 and IPv6 addresses (--anonymize-ips, -a).
  • User-specified sensitive words (--sensitive-words, -w). Note that any occurrence of a specified sensitive word will be replaced regardless of context, even if it is part of a larger string.
  • User-specified AS numbers (--as-numbers, -n). Note that any number matching a specified AS number will be anonymized.

Netconan attempts to preserve useful structure. For example,

  • Netconan preserves prefixes when anonymizing IPv4 and IPv6 addresses: IP addresses with a common prefix before anonymization will share the same prefix length after anonymization. For more information, see J. Xu et al., On the Design and Performance of Prefix-Preserving IP Traffic Trace Anonymization, ACM SIGCOMM Workshop on Internet Measurement, 2001 [link].
  • IPv4 classes and private-use prefixes (see IANA IPv4 assignments) are preserved by default, but can be overridden (with --preserve-prefixes e.g. --preserve-prefixes will preserve a leading octet 12 of IP addresses encountered but anonymize octets after the 12).
  • By default, the last 8 bits of each IP address are preserved. This prevents IP anonymization from breaking important network structure such as point-to-point IPv4 /30 links or NAT pools. This can be overridden to a new number B using --preserve-host-bits B, and it can be disabled entirely using --preserve-host-bits 0.
  • Specific addresses can optionally be preserved, e.g.
    • --preserve-addresses skips anonymizing the specified network or address. For example, --preserve-addresses, will skip anonymization for any address in the network and skip anonymizing
    • --preserve-private-addresses skips anonymizing all addresses that fall under private-use blocks.
  • AS number blocks are preserved (i.e. an anonymized public AS number will still be in the public AS number range after anonymization).
  • Standard password and hash formats (salted md5, Cisco Type 7, Juniper Type 9) are recognized and substituted with format-compliant replacements.

Netconan is deterministic when provided the same user-controllable salt (--salt, -s). Files processed using the same salt are compatible (e.g., IP addresses anonymized the same way) whether anonymized together or separately. Setting the salt in a configuration file is recommended, so that you can get compatible anonymization each time you use netconan.

For reversible operations (specifically, IP address anonymization), Netconan can produce a de-anonymized file (--undo, -u) when provided with the same salt used in anonymization (--salt, -s).

Running netconan

Netconan processes the input file or recursively processes files in the input directory (skipping files starting with .) and saves processed files at the specified output.

For more information about less commonly-used features, see the Netconan help (-h). For more information on config file syntax, see here.

usage: netconan [-h] [--version] [-a] [-c CONFIG] [-d DUMP_IP_MAP] -i INPUT
                OUTPUT [-p] [-r RESERVED_WORDS] [-s SALT] [-u]
                [-w SENSITIVE_WORDS] [--preserve-prefixes PRESERVE_PREFIXES]
                [--preserve-addresses PRESERVE_ADDRESSES]
                [--preserve-host-bits PRESERVE_HOST_BITS]

Args that can start with '--' can also be set in a config file (specified via
-c). If an arg is specified in more than one place, then command line values
override config file values which override defaults. Config file syntax
allows: key=value, flag=true, stuff=[a,b,c] (for more details, see here

optional arguments:
  -h, --help            show this help message and exit
  --version             Print version number and exit
  -a, --anonymize-ips   Anonymize IP addresses
  -c CONFIG, --config CONFIG
                        Netconan configuration file with defaults for these
                        CLI parameters
  -d DUMP_IP_MAP, --dump-ip-map DUMP_IP_MAP
                        Dump IP address anonymization map to specified file
  -i INPUT, --input INPUT
                        Input file or directory containing files to anonymize
                        Determines what level of logs to display
  -n AS_NUMBERS, --as-numbers AS_NUMBERS
                        List of comma separated AS numbers to anonymize
  -o OUTPUT, --output OUTPUT
                        Output file or directory where anonymized files are
  -p, --anonymize-passwords
                        Anonymize password and snmp community lines
  -r RESERVED_WORDS, --reserved-words RESERVED_WORDS
                        List of comma separated words that should not be
  -s SALT, --salt SALT  Salt for IP and sensitive keyword anonymization
  -u, --undo            Undo reversible anonymization (must specify salt)
                        List of comma separated keywords to anonymize
  --preserve-prefixes PRESERVE_PREFIXES
                        List of comma separated IP prefixes to preserve.
                        Specified prefixes are preserved, but the host bits
                        within those prefixes are still anonymized. To
                        preserve prefixes and host bits in specified blocks,
                        use --preserve-addresses instead
  --preserve-addresses PRESERVE_ADDRESSES
                        List of comma separated IP addresses or networks to
                        preserve. Prefixes and host bits within those networks
                        are preserved. To preserve just prefixes and anonymize
                        host bits, use --preserve-prefixes
                        Preserve private-use IP addresses. Prefixes and host
                        bits within the private-use IP networks are preserved.
                        To preserve specific addresses or networks, use
                        --preserve-addresses instead. To preserve just
                        prefixes and anonymize host bits, use --preserve-
  --preserve-host-bits PRESERVE_HOST_BITS
                        Preserve the trailing bits of IP addresses, aka the
                        host bits of a network. Set this value large enough to
                        represent the largest interface network (e.g., 8 for a
                        /24 or 12 for a /20) or NAT pool.