Manufacturer Usage Description (MUD) is a technique whereby constrained end devices (e.g., IoT devices) can signal to the network what sort of access and network functionality they require to properly function. The end device performs this signaling by issuing a URL in LLDP, DHCP, or as part of an X.509 certificate. A MUD Manager is a service sitting in the network that receives the MUD URL, fetches a MUD file containing access requirements provided by a manufacturer, and creates Access Control Lists (ACLs) that can be installed on network equipment to allow that access.
The MUD specification can be found in (https://tools.ietf.org/html/draft-ietf-opsawg-mud-25), which has been approved to be an IETF RFC. This implementation supports all abstractions, except model. In addition, source and destination IPv4 and IP networks from the ACL model are supported, so long as they are multicast addresses.
After you have installed the MUD Manager, guidance is available at (https://developer.cisco.com/docs/mud/#!mud-developer-guide) if you need help creating a MUD file, and/or preparing a device to emit a URL to a MUD file.
The MUD Manager is used by a RADIUS server to translate a MUD URL into access control policies. The MUD Manager receives REST APIs containing the MUD URL (and possibly other information), and returns RADIUS attributes that can be sent to a Network Access Device (NAD) such as an Ethernet switch. The NAD installs the policy on the access port, which restricts the device providing the MUD URL to just its required network access.
A MUD URL is an "https://..." file, which means that TLS is used to fetch the file.
The MUD manager depends on the following packages.
OpenSSL is used for cryptographic services, and is available on most Linux systems. If not, then a recent release will need to be installed. It may be available using a package installer (such as apt-get), else it can be downloaded from https://www.openssl.org.
If a Linux distribution has openssl, but you cannot link to it try:
sudo apt-get install -y libssl-dev # debianor
yum install openssl-devel # centoscJSON is used for JSON processing in "C". Download it from GitHub:
git clone https://github.com/DaveGamble/cJSON
cd cJSON
make
sudo make installMongoDB is used to store the MUD URLs, policy derived from the MUD URLs, and MAC addresses that are associated with a MUD URL.
Instructions for installing MongoDB with a package manager can be found
here.
Alternatively it can be downloaded with git, and the follow the instructions in its README.
git clone https://github.com/mongodb/mongo.gitThe MongoDB service should be started automatically when the system boots. If you see an indication that the MUD Manager cannot reach the MongoDB server, you can try
sudo service mongodb start # (Recent Debian/Ubuntu releases)
sudo /etc/init.d/mongod start # Amazon/CentOS\The Mongo C driver is needed for the MUD manager to communicate with MongoDB. Download from https://github.com/mongodb/mongo-c-driver/releases. We suggest version 1.7.0 or later, but in any case a version that supports PKG-CONFIG (this excludes the Debian package manager).
To retrieve, make and install 1.7.0:
wget https://github.com/mongodb/mongo-c-driver
cd mongo-c-driver
cmake
make
sudo make installLibcurl is used to fetch MUD files from a MUD file server.
sudo apt-get install libcurl4-openssl-dev # Debian/Ubuntuor
sudo yum install libcurl-devel # CentOS/AmazonIf you retrieve libcurl and build it on your own, you may wish to
build against OpenSSL rather than GNUTLS, as the latter dramatically
increases the number of dependencies (this includes such things as
the GSSAPI and MySQL, which are really unused in this case).
Run configure and make.
./configure
make
sudo make installThe default location for the configuration file is:
/usr/local/etc/mud_manager_config.jsonThe following fields can be set in the configuration file.
This defines whether the REST APIs should be http:// or https://. The
default configuration file setting is http://.
If https:// is used, then the MUD Manager will also need the following TLS-related fields added:
MUDManager_cert, with a pathname to the MUD Manager's signing certificateMUDManager_key, with a pathname to the MUD Manager's private keyEnterprise_CACert, with a pathname to the CA certificate that signed theMUDManager_cert
This provides for a VLAN when same-manufacturer is not used.
This directs the MUD manager to return ACLs only to enforce policy on the "ingress" direction (i.e., from the device), or whether to enforce policy on both ingress and egress (i.e., to and from the device). Its setting depends on the capabilities of the NAD.
The safest choice is to leave it as dACL-ingress-only, however if you have a NAD that will also enforce egress policy you should set it as dACL-ingress-egress.
In some cases, a RADIUS server will complete an Authentication exchange for a device before the NAD gives it a MUD URL associated with that device. When the association is subsequently made, the MUD policy will not become effective on the NAD before the next Authentication session. A convenient way to cause the Authentication to happen is for the MUD manager to send a Change of Authorization (CoA) to the NAD, instructing it to perform authentication with the RADIUS server again.
For the CoA to succeed, the MUD Manager must share a password with the NAD. Replace the sample password provided in the configuration file with the password you use on the NAD.
If the VLANs array is present, it consists of a pool of VLANs
available for assignment when same-manufacturer is present for a
given authority. These will be automatically assigned, and stored in
MUD-Manager's internal database. If they are removed from the
configuration file, they will still be used. If a vlan field
exists for a particular manufacturer, it will override the use of the
pool.
Each array entry consists of the following elements:
-
VLAN_ID: the value of the VLAN to be used. -
v4addrmask: a string in the form of a dotted quad and a wildcard mask also in the form of a dotted quad. For example:"v4addrmask" : "192.168.1.0 0.0.0.255" -
v6addrmask: a string in the form of a v6 network and a mask.
Note Bene all VLANs listed in configuration or in the database must have previously been configured in all switches using the same AAA server.
This array of manufacturers is optional. When present, it may contain information that includes an authority string, a set of certificates for validation, an optional VLAN, my-controller information for this particular instance, and any local network information to be used. If NOT present, the MUD manager will press on, but my-controller statements will be ignored. See below for more detail.
The authority portion of the URL, which defines the unique manufacturer. For
example, if the URL is "https://luminaire.example.com/Luminaire_150", the
authority portion of the URL is "luminaire.example.com". This same string
needs to be placed in the authority policy of the Manufacturer in the
configuration file.
The CA certificate for the manufacturer, which is used to verify the MUD file server signature.
The port used to contact the file server (e.g., 443).
These are used to define what is the local IP address for a "my-controller" statement found in a MUD file. If these are not present, the my-controller statement will be ignored.
These are used to translate a "local-networks" statement found in a MUD file.
If a "same-manufacturer" statement is found in the MUD file, this VLAN value is sent with the ACLs to the NAD. This field generally should not be used. Instead, create a group of VLAN entries in the VLANs array and allow MUD Manager to assign them.
For the VLAN there needs to be a statement such as "192.168.1.0 0.0.0.255" (or equivalent v6) to permit acces to that VLAN.
If a MUD file has a DNS name in it, and that name is not resolvable (say because you are doing testing), you can add a translation here. If you do not, a DNS lookup will be performed.
If a MUD file has a "controller" statement, it needs to be translated to an IP address. Do that here.
A site policy may provide additional restrictions to the devices. These can be defined as access control list statements here. The default policy included in the configuration policy is to block all other IP and ICMP packets.
Two scripts are included to manipulate the MUD Manager collections in MongoDB.
mud_clobber_db: This can be used to clean out the MUD Manager collections, which forces MUD files to be fetched and access policy to be re-gererated.mud_show_db: This displays the contents of the three collections used by the MUD Manager.
The examples directory includes an example of a "luminaire", which includes a sample MUD file, sample MUD file server, certificates, and instructions how to use the mud_test_command to invoke the MUD Manager.
A simple test command is included, which imitates REST APIs to the MUD Manager and verifies that the MUD Manager can download and process a MUD file.
If the "luminaire" example MUD file server is running, and the MUD manage is started on its default port, then the following test command should retrieve the MUD file and the return the ACLs contained within it.
mud_test_client -f Luminaire_150 -c 127.0.0.1 -p 8000 -w luminaire.example.comThe output should look something like this:
URL: https://luminaire.example.com/Luminaire_150
Starting RESTful client against http://127.0.0.1:8000/getaclname
with request {
"MUD_URI": "https://luminaire.example.com/Luminaire_150"
}
Got ACL Names
Full ACL Name 0: ACS:CiscoSecure-Defined-ACL=mud-21966-v4fr.in
ACLname: mud-21966-v4fr.in
Starting RESTful client against http://127.0.0.1:8000/getaclpolicy with request {
"ACL_NAME": "mud-21966-v4fr.in"
}
Username: mud-21966-v4fr.in
Got DACL contents:
ACE: ip:inacl#10=permit tcp any host 172.12.212.10 range 443 443 established
ACE: ip:inacl#20=permit udp any host 10.1.1.4 range 5684 5684
ACE: ip:inacl#30=permit udp any host 255.255.255.255 range 5683 5683
ACE: ip:inacl#40=permit tcp any eq 22 any
ACE: ip:inacl#41=deny ip any anyA new web user interface is now available just for testing purposes. Beware that there is no current authentication mechanism.
Prerequisites:
- PHP 2.7 or later
- The PHP mongodb extension.
- composer
The configure script will not test for PHP or mongodb, but will test for composer.
To install, issue the configure command with --with-webui=/installdirectory where the installdirectory is where you want the HTML installed.
- Basic UI support.
- Multicast support. MUD files can contain multicast addresses.
- Source tree reorganized.
- VLAN support improved
- Support for new RESTful endpoint to update server
- Github space correction.
The latest code contains a great many bug fixes and a number of additions. Here's a brief list:
- Limit of 11 ACE lines removed. Memory is now realloced as required.
- VLANs are pulled from a pool. Manufacturer entries should not list them.
- The config file is now versioned.
- Add a default for local-networks
- Fix a memory corruption issue.
- Relax the idea that somehow "protocol" was required in the MUD file.
- Relax the MIME check on MUD files. Yes, MUD File Servers should use application/json, but as most people are just going to use apache, let's not be too pedantic.
To begin with, you don't need to list a manufacturer in the config file. Until you do, of course, the controller functions are quite limited. We are also now using the updated MUD specification, reading in all the informational elements into the MongoDB. This will become more important later on as we begin to offer at least something of a graphical interface to All of This.
Rashmikant Shah
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