With the Introduction of IOX XR 6.0, the complete IOS XR software architecture has migrated to a open source infrastructure centered around the Linux Operating System. With the Adoption of Linux and Linux Containers (LXCs) some major change have been introduce in several areas; The monolithic set of XR features has been dis-aggregated in a collection of RPM packages that can be upgraded trough local or remote repositories. The Linux environment comes with its own authentication mechanism and user privileges. With XR and Linux processes residing side-by-side inside the same namespace, it is important to control the installation and execution of these processes.
Packages and ISOs are delivered in a tar file. included in that tar file is a readme file that contain a MD5 sum for all the files. MD5 sum are a good way to verify the integrity of the file using the md5sum utility on Unix. md5sum generate a 128-bit value known as the “digital fingerprint.” If two files have different MD5 sums, the files are definitely different whereas if two files have the same MD5 sum, it is highly likely the files are exactly alike. MD5 is technically a cryptography hash function which essentially means that the risk of producing collisions is really low but possible.
Example of verifying md5sum from the Linux shell using unnamed pipes.
[email protected]:~$ diff -awsy <(grep mgbl README-ncs5k-k9sec-6.0.0 | cut -d' ' -f1) <(md5sum ncs5k-mgbl-126.96.36.199-r600.x86_64.rpm-6.0.0 | cut -d' ' -f1) 7a0e22ea86622dfc2293179d6fb52721 7a0e22ea86622dfc2293179d6fb52721 Files /dev/fd/63 and /dev/fd/62 are identical
or using a simple script:
!/bin/bash if [ -z $3 ]; then echo "file + readme + feature needed" echo "usage: 0? " exit fi export csum=$(grep $3 $2 | cut -d' ' -f1) export fsum=$(md5sum $1 | cut -d' ' -f1) echo $csum echo $fsum if [ "$csum" = "$fsum" ]; then echo "MD5sum are identical" else echo "MD5sum are different" fi
[email protected]:~$ chkmd5.sh ncs5k-mgbl-188.8.131.52-r600.x86_64.rpm-6.0.0 README-ncs5k-k9sec-6.0.0 mgbl 7a0e22ea86622dfc2293179d6fb52721 7a0e22ea86622dfc2293179d6fb52721 MD5sum are identical
IOS XR 6.0.0 and above use the RPM format for all its packages, the RPM format include the capability to digitally sign packages using a SHA-1 key. At this time none of the IOS XR packages are signed, this feature will be available in a future release.
Some third party packages embed a RSA/SHA-1signature, to install these packages, the public key of the provider can be verified before and during package installation.
Example for the puppet client
1) Key Presence
On the local repository server, you can verify if the package has been signed by the provider.
[email protected]:~$ rpm -qpi puppet-agent-1.4.1-1.cisco_wrlinux7.x86_64.rpm | grep Signature warning: puppet-agent-1.4.1-1.cisco_wrlinux7.x86_64.rpm: Header V4 RSA/SHA1 Signature, key ID 4bd6ec30: NOKEY Signature : RSA/SHA1, Thu 24 Mar 2016 03:05:33 PM PDT, Key ID 1054b7a24bd6ec30
2) Key Verification
On the local repository download and import the public key from the package provider, this step can be performed multiple time to verify the integrity of all packages in the local repository.
[email protected]:~$ wget http://yum.puppetlabs.com/RPM-GPG-KEY-puppetlabs [email protected]:~$ rpm --import RPM-GPG-KEY-puppetlab [email protected]:~$ rpm -Kv puppet-agent-1.4.1-1.cisco_wrlinux7.x86_64.rpm puppet-agent-1.4.1-1.cisco_wrlinux7.x86_64.rpm: Header V4 RSA/SHA1 Signature, key ID 4bd6ec30: OK Header SHA1 digest: OK (fd954ea78e24ea32fdbaf3be045087ffe4c277ae) V4 RSA/SHA1 Signature, key ID 4bd6ec30: OK MD5 digest: OK (5eb0292058ba82449b7fb6eaa62fc102)
3) Create a Repository Pointer
On the Router, create a .repo file in /etc/yum/repos.d that enable key verification of packages, keys can also be copied on a local repository if this repository is secure.
[puppetlabs] name=puppetlabs baseurl=http://galaxy-42.cisco.com/Packages gpgcheck=1 gpgkey=http://yum.puppetlabs.com/RPM-GPG-KEY-puppetlabs enabled=1
4) Package Installation from local repository
xr-vm_node0_RP0_CPU0:~# yum install puppet-agent Loaded plugins: app_plugin, downloadonly, protect-packages puppetlabs | 2.9 kB 00:00 Setting up Install Process Resolving Dependencies --> Running transaction check ---> Package puppet-agent.x86_64 0:1.4.1-1.cisco_wrlinux7 will be installed --> Finished Dependency Resolution Dependencies Resolved ====================================================================================================== Package Arch Version Repository Size ====================================================================================================== Installing: puppet-agent x86_64 1.4.1-1.cisco_wrlinux7 puppetlabs 41 M Transaction Summary ====================================================================================================== Install 1 Package Total download size: 41 M Installed size: 143 M Is this ok [y/N]: y Retrieving key from http://yum.puppetlabs.com//RPM-GPG-KEY-puppetlabs Importing GPG key 0x4BD6EC30: Userid: "Puppet Labs Release Key (Puppet Labs Release Key) <[email protected]>" From : http://yum.puppetlabs.com//RPM-GPG-KEY-puppetlabs Is this ok [y/N]: y Downloading Packages: puppet-agent-1.4.1-1.cisco_wrlinux7.x86_64.rpm | 41 MB 00:01 Running Transaction Check Running Transaction Test Transaction Test Succeeded Running Transaction Installing : puppet-agent-1.4.1-1.cisco_wrlinux7.x86_64 1/1 Installed: puppet-agent.x86_64 0:1.4.1-1.cisco_wrlinux7 Complete!