In part 1 of this series we were introduced to OpenSCAP and the process of running scans via the SCAP workbench. In part 2, we explored concepts and components that define security/vulnerability scans. In this 3rd post we are going to dive into the command line operation.
Let’s get started with oscap.
In RHEL 7 oscap can be installed with the following command
So this one is pretty simple. However, I found a lot of misinformation along the way, so I figured that I would jot the proper (and most simple) process here.
Symptoms: a RHEL (or variant) VM that takes a very long time to boot. On the VM console, you can see the following output while the VM boot process is stalled and waiting for a timeout. Note that the message below has nothing to do with cloud init, but its the output that I have most often seen on the console while waiting for a VM to boot.
[106.325574} random: crng init done
Note that I have run into this issue in both OpenStack (when booting from external provider networks) and in KVM.
Upon initial boot of the VM, run the command below.
Seriously, that’s it. No need to disable or remove cloud-init services. See reference.
According to Wikipedia, “Link Layer Discovery Protocol (LLDP) is a vendor-neutral link layer protocol in the Internet Protocol Suite used by network devices for advertising their identity, capabilities, and neighbors on an IEEE 802 local area network, principally wired Ethernet”
LLDP is often what you will find running on non-Cisco switches and routers (which usually run CDP). If you want to use tcpdump to capture northbound switch port information, you can use the example below as a guide.
# tcpdump -nn -v -i p4p2 ether proto 0x88cc
tcpdump: WARNING: p4p2: no IPv4 address assigned
tcpdump: listening on p4p2, link-type EN10MB (Ethernet), capture size 65535 bytes
19:00:12.559556 LLDP, length 218
Chassis ID TLV (1), length 7
Subtype MAC address (4): f4:8e:38:28:b6:89
Port ID TLV (2), length 11
Subtype Interface Name (5): ethernet11
Time to Live TLV (3), length 2: TTL 120s
Port Description TLV (4), length 39: BCF Port ethernet11
System Name TLV (5), length 22: Switch01
Plotnetcfg is a Linux utility that you can use to scan the networking configuration on a server and output the configuration hierarchy to a file. Plotnetcfg is most useful when troubleshooting complex virtual networks with all sorts of bonds and bridges, the likes of which you will find on KVM nodes, or OpenStack Controller nodes.
You can install plot on RHEL/Centos as shown below.
# yum -y plotnetcfg.x86_64
You will also want to install the “dot” command which is installed with graphiz. See below.
# yum -y install graphviz.x86_64
Now that the bits and pieces are installed we can run the command below which outputs to PDF file named file.pd
# plotnetcfg | dot -Tpdf > file.pd
If you want to, you can also use “convert” to convert the PDF to a jpg. For example, I exported to jpg to embed below.
Super clean, and super easy to read and understand
In this post I will walk though the steps that I used to setup software raid using mdadm on my RHEL 7.2 server.
The disks in my server are shown below.
/dev/sda – 64gb SSD – OS disk
/dev/sdb – 4TB – Unused
/dev/sdc – 4TB – Unused
My plan is to create a RAID 1 mirror from the two 4TB drives (sdb and sdc) and mount the mirrored device to “/var/lib/libvirt/images” for use via KVM.
First we need to partition the disks. Note that we cannot use fdisk as does not support partition sizes over 4Tb in size. See below.
[root@titan]# fdisk /dev/sdb
WARNING: The size of this disk is 4.0 TB (4000000000000 bytes).
DOS partition table format can not be used on drives for volumes
larger than (2199023255040 bytes) for 512-byte sectors. Use parted(1) and GUID partition table format (GPT).
Instead we will use parted. See steps below. Note that each step is repeated as we have two disks.