##Trust Model For NLSR
The trust model of NLSR is semi-hierarchical. An example certificate signing hierarchy is:
root
|
+--------------+---------------+
site1 site2
| |
+---------+---------+ +
operator1 operator2 operator3
| | |
+-----+-----+ +----+-----+ +-----+-----+--------+
router1 router2 router3 router4 router5 router6 router7
| | | | | | |
+ + + + + + +
NLSR NSLR NSLR NSLR NSLR NSLR NSLR
Each entity's name and corresponding certificate name follow the convention below:
Entity | Identity Name | Example | Certificate Name Example -------- | ------------------------------------------------- | ------------------------------- | ----------------------------------------------- root | /\<network\> | /ndn | /ndn/KEY/ksk-1/ID-CERT/%01 site | /\<network\>/\<site\> | /ndn/edu/ucla | /ndn/edu/ucla/KEY/ksk-2/ID-CERT/%01 operator | /\<network\>/\<site\>/%C1.Operator/\<operator-name\> | /ndn/edu/ucla/%C1.Operator/op1 | /ndn/edu/ucla/%C1.Operator/op1/KEY/ksk-3/ID-CERT/%01 router | /\<network\>/\<site\>/%C1.Router/\<router-name\> | /ndn/edu/ucla/%C1.Router/rt1 | /ndn/edu/ucla/%C1.Router/rt1/KEY/ksk-4/ID-CERT/%01 NLSR | /\<network\>/\<site\>/%C1.Router/\<router-name\>/NLSR | /ndn/edu/ucla/%C1.Router/rt1/NLSR | /ndn/edu/ucla/%C1.Router/rt1/NLSR/KEY/ksk-5/ID-CERT/%01
Users should create keys according to the naming and signing hierarchies above.
In a network, every router should have the root certificate configured as a trust anchor. For each site, at least one router should publish the site certificate, at least one router should publish the certificate of the site operator. Each router should publish its own certificate. All this information should be explicitly specified in nlsr.conf file. For example, the following configuration file indicates that NLSR should publish the site certificate and the router certificate:
...
security
{
validator
{
...
}
cert-to-publish "site.cert" ; name of the file which contains the site certificate (optional).
cert-to-publish "router.cert" ; name of the file which contains the router certificate (required).
}
Note that when a new NLSR instance is created, it will create a new key for the instance; generating the certificate for the new NLSR key is handled internally in NLSR. Therefore, user does not have to explcitly create keys and certificate for each NLSR instance.
For key and certificate generation, please refer to the ndnsec tool kit.
Security Configuration: Every machine in network will have the same set of security rules to configure. However, different machine will have different configuration commands "cert-to-publish" depending on responsibility. Let us use the same topology used for example(https://github.com/named-data/NLSR/blob/master/docs/TOPOLOGY.md).
ndnsec-key-gen generates a key
Lets assume that /ndn/memphis.edu/router1 is the router who is responsible as the memphis site router and also responsible as root which is the trust anchor of the network. So router in memphis will do the following key creation and signing.
NOTE: The first two steps may not apply to everyone as the root certificate and the site certificate are usually present at a testbed outside the scope of NLSR. These steps will help if you are testing an isolated testbed.
Create root key and self signed certificate with prefis /ndn $ndnsec-key-gen -n /ndn > root.cert This root.cert will be configured by "cert-to-publish" commands in nlsr.conf
Generate key for site prefix /ndn/edu/memphis and sign it by root key $ndnsec-key-gen -n /ndn/edu/memphis > selfsigned_site.cert $ndnsec-cert-gen -S 20140701000000 -E 20150701000000 -N "University of Memphis" -s /ndn -p /ndn/edu/memphis -r selfsigned_site.cert > site.cert
Generate key for operator and sign it by memphis site key. Lets assume that operator name in Memphis site is ndnuser, so the prefix is /ndn/edu/memphis/%C1.O.N./ndnuser $ndnsec-key-gen -n /ndn/edu/memphis/%C1.Operator/ndnuser > selfsigned_operator.cert $ndnsec-cert-gen -S 20140701000000 -E 20150701000000 -N "University of Memphis Operator" -s /ndn/edu/memphis -p /ndn/edu/memphis/%C1.Operator/ndnuser -r selfsigned_operator.cert > operator.cert
Generate key for router and sign it with operator's key $ndnsec-key-gen /ndn/edu/memphis/%C1.Router/router1 > selfsigned_router.cert $ndnsec-cert-gen -S 20140701000000 -E 20150701000000 -N "University of Memphis Router" -s /ndn/edu/memphis/%C1.Operator/ndnuser -p /ndn/edu/memphis/%C1.Router/router1 -r selfsigned_router.cert > router.cert
Key creation and signing is done for /ndn/memphis.edu/router1. In nlsr.conf this router will have this lines
cert-to-publish "root.cert" cert-to-publish "site.cert" cert-to-publish "operator.cert" cert-to-publish "router.cert"
Here is the entire security configuraion of the router1 (As seen in nlsr.conf. Note that only the semi-colons before the certs have been removed, rest is same)
security
{
validator
{
rule
{
id "NSLR Hello Rule"
for data
filter
{
type name
regex ^[^<NLSR><INFO>]*<NLSR><INFO><><>$
}
checker
{
type customized
sig-type rsa-sha256
key-locator
{
type name
hyper-relation
{
k-regex ^([^<KEY><NLSR>]*)<NLSR><KEY><ksk-.*><ID-CERT>$
k-expand \\1
h-relation equal
p-regex ^([^<NLSR><INFO>]*)<NLSR><INFO><><>$
p-expand \\1
}
}
}
}
rule
{
id "NSLR LSA Rule"
for data
filter
{
type name
regex ^[^<NLSR><LSA>]*<NLSR><LSA>
}
checker
{
type customized
sig-type rsa-sha256
key-locator
{
type name
hyper-relation
{
k-regex ^([^<KEY><NLSR>]*)<NLSR><KEY><ksk-.*><ID-CERT>$
k-expand \\1
h-relation equal
p-regex ^([^<NLSR><LSA>]*)<NLSR><LSA>(<>*)<><><>$
p-expand \\1\\2
}
}
}
}
rule
{
id "NSLR Hierarchy Exception Rule"
for data
filter
{
type name
regex ^[^<KEY><%C1.Router>]*<%C1.Router>[^<KEY><NLSR>]*<KEY><ksk-.*><ID-CERT><>$
}
checker
{
type customized
sig-type rsa-sha256
key-locator
{
type name
hyper-relation
{
k-regex ^([^<KEY><%C1.Operator>]*)<%C1.Operator>[^<KEY>]*<KEY><ksk-.*><ID-CERT>$
k-expand \\1
h-relation equal
p-regex ^([^<KEY><%C1.Router>]*)<%C1.Router>[^<KEY>]*<KEY><ksk-.*><ID-CERT><>$
p-expand \\1
}
}
}
}
rule
{
id "NSLR Hierarchical Rule"
for data
filter
{
type name
regex ^[^<KEY>]*<KEY><ksk-.*><ID-CERT><>$
}
checker
{
type hierarchical
sig-type rsa-sha256
}
}
trust-anchor
{
type file
file-name "root.cert"
}
}
;cert-to-publish "root.cert" //optional, a file containing the root certificate. only the router
//that is designated to publish root cert needs to specify this
cert-to-publish "site.cert" //optional, a file containing the root certificate. only the router
//that is designated to publish site cert need to specify this
cert-to-publish "operator.cert" //optional, a file containing the root certificate. only the
//router that is designated to publish operator cert need to
//specify this
cert-to-publish "router.cert" //required, a file containing the router certificate.
}
Now lets see how /ndn/colostate.edu/router2 will create and sign keys. Let assume that this router is responsible for hosting site keys and operator keys of colorado site.
Generate key for site prefix /ndn/edu/colorado $ndnsec-key-gen -n /ndn/edu/memphis > selfsigned_site.cert
Send this cert to Memphis site ( as in example Memphis is the root) and get it signed by root. After you get back the site please put it in your convenient certificate directory.
Generate key for operator and sign it by colorado site key. Lets assume that operator name in Colorado site is testop, so the prefix is /ndn/edu/colorado/%C1.O.N./testop $ndnsec-key-gen -n /ndn/edu/colorado/%C1.Operator/testop > unsigned_operator.cert $ndnsec-cert-gen -S 20140701000000 -E 20150701000000 -N "Colorado State University Operator" -s /ndn/edu/colorado -p /ndn/edu/colorado/%C1.Operator/testop -r selfsigned_operator.cert > operator.cert
Generate key for router and sign it with operator's key $ndnsec-key-gen /ndn/edu/colorado/%C1.Router/router2 > unsigned_router.cert $ndnsec-cert-gen -S 20140701000000 -E 20150701000000 -N "Colorado State University Router" -s /ndn/edu/colorado/%C1.Operator/testop -p /ndn/edu/colorado/%C1.Router/router2 -r selfsigned_router.cert > router.cert
Key creation and signing is done for /ndn/edu/colorado/router2. In nlsr.conf this router will have these lines
cert-to-publish "site.cert" cert-to-publish "operator.cert" cert-to-publish "router.cert"
(The rest of the security configuration is same as the other router.)
Colorado also need to bring the root.cert from Memphis and put it in the certificate directory as it is configured as trust anchor.
Now both Memphis and Colorado router is ready to run with security configuration. Arizona router will follow the same step as Colorado to configure security for NLSR.
To disable packet validation in NLSR, you need to change the configuration file in section: security.validator.trust-anchor
trust-anchor
{
type file
file-name "root.cert"
}
change the previous section in security configuration to below
trust-anchor
{
type any
}
With this change, packets are still signed, but validation will be skipped.