dutsnekcirf's questions

We recently setup a FreeIPA server. We're using it for central user management, DNS, and CA. It's been working great with one exception.

Some of the workstations that authenticate with this FreeIPA server are several thousands of miles away. Round Trip Time is about 300 ms. We've noticed some unpredictable authentication failures on these machines. One second they'll fail to authenticate a login attempt and then they'll succeed to authenticate only seconds later. We're thinking that the delay is the culprit.

Is there a way to extend the timeout on the clients? Alternatively, we've been considering setting up an IPA replica at the location where these workstations reside. How would the high latency link affect the replica's ability to replicate with the primary server?

I'm trying to dynamically configure multiple NFS servers in my system by generating their /etc/exports files using Ansible. I'm hoping to be able to do this with a jinja2 template. It's the jinja2 template that I can't figure out based on my exports list.

I have the following variables defined in my nfs role:

site_nfs_servers: ['ansibletarget1', 'ansibletarget2']

exports:
  - server: "ansibletarget1"
    shares:
      - path: "/my/first/share/path"
        client: "*"
        options: "rw,sync"
      - path: "/my/second/share/path"
        client: "*"
        options: "rw,sync,root_squash"
  - server: "ansibletarget2"
    shares:
      - path: "/another/shared/path/different/server"
        client: "*"
        options: "ro,sync"

I then have the following ansible play to generate the template:

- name: Generate the exports file.
  template:
    src: exports.j2
    dest: /etc/exports
    owner: root
    group: root
    mode: '0750'

My template currently looks like this:

{% for export in exports %}
{% if ansible_hostname in export.server %}
{% for share in shares %}
{{ share.path }} {{ share.client }} {{ share.options }}
{% endfor %}
{% endif %}
{% endfor %}

I don't think I'm anywhere near close to having the correct template structure. How on earth does one iterate through this list?

I have two Linux routers (RHEL 7) participating in a redundant VRRP configuration provided by the keepalived package version 2.0.20. These two routers used to be running RHEL 6 and keepalived version 2.0.16 but we recently upgraded them to the aforemented versions.

Before we upgraded I had a script that I could run on the backup router that would cause the router to take over as the master router. The script would glean the priority value of the current master router and then increment its own priority to be 1 higher and then restart the keepalived service. This would cause the backup router to take over as the master.

The script would glean the value of the current master router by issuing the following commands:

kill -s $(keepalived --signum=DATA) $(cat /var/run/keepalived.pid)
vrrpPriority='more /tmp/keepalived.data | grep -m1 "Master priority" | awk '{print $4}''

Now that we've upgraded, it doesn't look like the first command does anything anymore. The command appears to execute without errors, but I never get a generated file in /tmp/keepalived.data. So the second command fails since that file doesn't exist.

Is there a better or different way of gleaning the priority value of the current master router?

Another difference is that when we were running in RHEL 6, keepalived was running as an upstart script whereas today keepalived is running as a systemd service. All other aspect of keepalived appear to be working correctly.

Our network supports many multicast streams using pimd. Many (but not all) of those multicast streams only flow if we use the "altnet multicast_source_ip masklen 24" statement in the phyint section of the pimd.conf file. Those multicast flows are dynamically added or removed as certain network devices are brought up/down based on specific events throughout the day. Throughout the day the pimd.conf file could have these altnet statements added or removed many times. Each time this occurs we have to issue the "pimd -l" command in order for the change to take affect. Each time this command is issued the daemon is reloaded and the mroute table gets wiped. After a short period of rediscovery, the mroutes slowly find their way back into the multicast routing table. This causes a short disruption to pre-existing multicast traffic flow until all of the mroutes are repopulated.

I would like to know if it's possible to add/remove altnet directives without having to edit the pimd.conf file and issue the pimd -l command to reload the config. In other words, could they be added or removed during runtime? Or added without affecting any existing multicast flows/routes?

I'm attempting to configure an openvpn client on a raspberry pi 3 b+. The raspberry pi is running CentOS 7 armhfp.

I installed openvpn from the EPEL repository for armhfp platforms. I've placed my config and associated keys and auth file in /etc/openvpn

[root@raspberrypi openvpn]# ll
total 24
drwxr-x---. 2 root openvpn 4096 Jan  1  1970 client
-rwxrwxrwx. 1 root root    2186 Jan 25 22:17 mullvad_ca.crt
-rwxrwxrwx. 1 root root     985 Jan  1  1970 mullvad_us.conf
-rwxrwxrwx. 1 root root      19 Jan 25 22:17 mullvad_userpass.txt
drwxr-x---. 2 root openvpn 4096 Nov 18 14:06 server
-rwxrwxrwx. 1 root root    1301 Jan 25 22:17 update-resolv-conf
[root@raspberrypi openvpn]#

I'm attempting to start the service with the command: systemctl start openvpn-client@mullvad_us

When I do it fails with the following status:

[root@raspberrypi openvpn]# systemctl status openvpn-client@mullvad_us -l
● openvpn-client@mullvad_us.service - OpenVPN tunnel for mullvad_us
   Loaded: loaded (/usr/lib/systemd/system/[email protected]; enabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Sun 2020-01-26 01:17:19 UTC; 3h 10min ago
     Docs: man:openvpn(8)
           https://community.openvpn.net/openvpn/wiki/Openvpn24ManPage
           https://community.openvpn.net/openvpn/wiki/HOWTO
  Process: 994 ExecStart=/usr/sbin/openvpn --suppress-timestamps --nobind --config %i.conf (code=exited, status=1/FAILURE)
 Main PID: 994 (code=exited, status=1/FAILURE)

Jan 26 01:17:19 raspberrypi systemd[1]: Starting OpenVPN tunnel for mullvad_us...
Jan 26 01:17:19 raspberrypi openvpn[994]: Options error: In [CMD-LINE]:1: Error opening configuration file: mullvad_us.conf
Jan 26 01:17:19 raspberrypi openvpn[994]: Use --help for more information.
Jan 26 01:17:19 raspberrypi systemd[1]: openvpn-client@mullvad_us.service: main process exited, code=exited, status=1/FAILURE
Jan 26 01:17:19 raspberrypi systemd[1]: Failed to start OpenVPN tunnel for mullvad_us.
Jan 26 01:17:19 raspberrypi systemd[1]: Unit openvpn-client@mullvad_us.service entered failed state.
Jan 26 01:17:19 raspberrypi systemd[1]: openvpn-client@mullvad_us.service failed.

It appears to be failing to read my mullvad_us.conf file. I've given it full 777 permissions as well as tried to change its ownership to openvpn:openvpn. I've also disabled selinux just in case that's the problem. I've also moved the files into /etc/openvpn/client with no success as well.

If I start openvpn from the command line it works fine. I'll run the command: "nohup openvpn --config /etc/openvpn/mullvad_us.conf &" and the tunnel builds and forms correctly.

I just can't get it to come up automatically at bootup. I'm planning to run this in a headless manner and don't want to have to ssh into the device each time I power it on just to get the vpn tunnel up.

I've seen articles online saying to edit the file at /etc/default/openvpn but that file doesn't exist for some reason and I can't help but think it's due to the flavor of CentOS that I'm running. At this point I'm pretty stumped. Any help would be hugely appreciated.

I'm attempting to install a FreeRADIUS server on a RHEL 6.9 VM. This VM is operating in FIPS mode. I'm running into the problem described in a Red Hat bug report found here.

According to that bug report from March of 2015 the RADIUS protocol requires MD5 support. FreeRADIUS (and RADIUS) can therefore not be supported in FIPS mode.

I'm hoping that in the 3 years that have transpired since that bug report there's been a fix or workaround that I can implement to get around this issue. Unfortunately, I'm restricted to running in FIPS mode per DISA STIG requirements. Is anyone aware of a way to get FreeRADIUS to work on a machine that's operating in FIPS mode?

I have a Linux machine that is being used as a router. It has quagga installed and has ip forwarding enabled. It's forming an OSPF adjacency with a 3925 Cisco router.

I'm being asked to ensure that this Linux machine (running Redhat 6.8) will not send any ICMP Unreachable notifications. I know that on a Cisco router I would simply set "no icmp unreachable" on any interfaces that need it. But how could I be certain that they're disabled on a Linux machine?

I'm also being asked to ensure that no "ICMP Mask Reply" messages get sent from the router. Likewise, I know that on a Cisco router the "no ip mask-reply" command would be used. Is there an equivalent type of setting in Redhat?

Thanks for any help.

I have a machine located in a secure environment that does not have access to the internet. I has a base load of CentOS with a handful of additional RPMs. This includes a basic install of PERL with no additional modules. Nor does it have GCC installed so I can't install new modules manually nor use CPAN to install them. Therefore, I need a pure Perl solution.

I've been asked to create a Perl script that will validate that the machine has a specific list of RPMs installed and that they're a specific version or newer.

Here's what I have so far:

#!/usr/bin/perl

use strict;
use warnings;

# This is the list of RPMs to look for on the machine.
my @RPMs = ("bwm-ng",
        "celt051",
        "device-mapper-multipath",
        "device-mapper-multipath-libs",
        "dhcp",
        "dhcp-common",
        "ebtables",
        "freeglut",
        "glusterfs-api",
        "glusterfs-libs",
        "gnutls-utils",
        "gpm",
        "hmaccalc",
        "iftop",
        "iperf",
        "ipsec-tools",
        "iptraf",
        "iscsi-initiator-utils",
        "libsysfs",
        "lm_sensors",
        "lm_sensors-libs",
        "log4cpp",
        "lrzsz",
        "lzop",
        "mcsctrans",
        "minicom",
        "nc",
        "netcf-libs",
        "net-snmp",
        "net-snmp-libs",
        "net-snmp-utils",
        "omping",
        "perl-AppConfig",
        "perl-Pod-POM",
        "perl-Template-Toolkit",
        "pimd",
        "python-lxml",
        "quagga",
        "radvd",
        "smcroute",
        "usbredir",
        "yajl");

# These are the RPM versions that they should be equal to or newer than.
my @RPMVersions = ("bwm-ng-0.6-6.el6.2.x86_64",
        "celt051-0.5.1.3-0.el6.x86_64",
        "device-mapper-multipath-0.4.9-87.el6.x86_64",
        "device-mapper-multipath-libs-0.4.9-87.el6.x86_64",
        "dhcp-4.1.1-49.P1.el6.centos.x86_64",
        "dhcp-common-4.1.1-49.P1.el6.centos.x86_64",
        "ebtables-2.0.9-6.el6.x86_64",
        "freeglut-2.6.0-1.el6.x86_64",
        "glusterfs-api-3.4.0.57rhs-1.el6_5.x86_64",
        "glusterfs-libs-3.4.0.57rhs-1.el6_5.x86_64",
        "gnutls-utils-2.8.5-18.el6.x86_64",
        "gpm-1.20.6-12.el6.x86_64",
        "hmaccalc-0.9.12-2.el6.x86_64",
        "iftop-1.0-0.7.pre4.el6.x86_64",
        "iperf-2.0.5-11.el6.x86_64",
        "ipsec-tools-0.8.0-25.3.x86_64",
        "iptraf-3.0.1-14.el6.x86_64",
        "iscsi-initiator-utils-6.2.0.873-14.el6.x86_64",
        "libsysfs-2.1.0-7.el6.x86_64",
        "lm_sensors-3.1.1-17.el6.x86_64",
        "lm_sensors-libs-3.1.1-17.el6.x86_64",
        "log4cpp-1.0-13.el6_5.1.x86_64",
        "lrzsz-0.12.20-27.1.el6.x86_64",
        "lzop-1.02-0.9.rc1.el6.x86_64",
        "mcsctrans-0.3.1-4.el6.x86_64",
        "minicom-2.3-6.1.el6.x86_64",
        "nc-1.84-24.el6.x86_64",
        "netcf-libs-0.2.4-3.el6.x86_64",
        "net-snmp-5.5-54.el6.x86_64",
        "net-snmp-libs-5.5-54.el6.x86_64",
        "net-snmp-utils-5.5-54.el6.x86_64",
        "omping-0.0.4-1.el6.x86_64",
        "perl-AppConfig-1.66-6.el6.x86_64",
        "perl-Pod-POM-0.25-2.el6.x86_64",
        "perl-Template-Toolkit-2.22-5.el6.x86_64",
        "pimd-2.3.0-1.x86_64",
        "python-lxml-2.2.3-1.1.el6.x86_64",
        "quagga-0.99.23.1-2014082501.x86_64",
        "radvd-1.6-1.el6.x86_64",
        "smcroute-2.0.0-0.x86_64",
        "usbredir-0.5.1-2.el6.x86_64",
        "yajl-1.0.7-3.el6.x86_64");

my $RPMname; #This reprepsents an individual RPM name within the @RPMs array.

foreach $RPMname (@RPMs){ # Loop through the @RPMs array and query the RPM database for each RPM.
    my $cmd = "rpm -qa | grep " . $RPMname;

    my @cmdResults = `$cmd`;

    if (! @cmdResults){
        print "\tMissing RPM: " . $RPMname . "\n\n"; # If the RPM isn't installed; inform the user.
    } else {
        foreach(@cmdResults){
            print "\t" . $_ . "\n"; # Print the version of the RPM that's currently installed.

            # Compare the RPM version that's installed with the corresponding version that should be installed
            # as listed in the @RPMVersions array.
            # write some magic here. <------

        }
    }
}

exit(0);

I've found what appears to be a possible solution but I can't seem to figure out how to adjust the code of fit my scenario.

see here: http://www.perlmonks.org/bare/?node=240384

I can't use RPM::VersionSort or several of the other RPM related modules because of the restrictions that I mentioned above.

Any help would be hugely appreciated.

Thanks!

I have a mini-pc with six network interfaces running CentOS 7.2 with Kernel 3.10 with a minimal install.

I want to name my interfaces net0-net5. To do so I'm trying to follow the suggestions mentioned here: http://www.freedesktop.org/wiki/Software/systemd/PredictableNetworkInterfaceNames/

In the above article it states that in order to rename my interfaces I need to create .link files and place them in /etc/systemd/network. This is the new way in which one is required to rename their network interfaces in compliance with the systemd-networkd.

I'm finding however, that the systemd-networkd service won't start and without this service running, I don't think I can name my interfaces at all.

See the following:

systemctl --failed -l
  UNIT                     LOAD   ACTIVE SUB    DESCRIPTION
<E2><97><8F> systemd-networkd.service loaded failed failed Network Service
<E2><97><8F> systemd-networkd.socket  loaded failed failed networkd rtnetlink so

LOAD   = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB    = The low-level unit activation state, values depend on unit type.

2 loaded units listed. Pass --all to see loaded but inactive units, too.
To show all installed unit files use 'systemctl list-unit-files'.


systemctl  status systemd-networkd -l
��● systemd-networkd.service - Network Service
   Loaded: loaded (/usr/lib/systemd/system/systemd-networkd.service; enabled; vendor preset: enabled)
   Active: failed (Result: start-limit) since Tue 2011-05-10 01:45:45 UTC; 32min ago
     Docs: man:systemd-networkd.service(8)
  Process: 317 ExecStart=/usr/lib/systemd/systemd-networkd (code=exited, status=226/NAMESPACE)
 Main PID: 317 (code=exited, status=226/NAMESPACE)

May 10 01:45:45 localhost systemd[1]: Unit systemd-networkd.service entered failed state.
May 10 01:45:45 localhost systemd[1]: systemd-networkd.service failed.
May 10 01:45:45 localhost systemd[1]: systemd-networkd.service has no holdoff time, scheduling restart.
May 10 01:45:45 localhost systemd[1]: start request repeated too quickly for systemd-networkd.service
May 10 01:45:45 localhost systemd[1]: Failed to start Network Service.
May 10 01:45:45 localhost systemd[1]: Unit systemd-networkd.service entered failed state.
May 10 01:45:45 localhost systemd[1]: systemd-networkd.service failed.
May 10 01:45:45 localhost systemd[1]: start request repeated too quickly for systemd-networkd.service
May 10 01:45:45 localhost systemd[1]: Failed to start Network Service.
May 10 01:45:45 localhost systemd[1]: systemd-networkd.service failed.

systemctl  status systemd-networkd.socket -l                                                             
��● systemd-networkd.socket - networkd rtnetlink socket
   Loaded: loaded (/usr/lib/systemd/system/systemd-networkd.socket; enabled; vendor preset: disabled)
   Active: failed (Result: service-failed-permanent) since Tue 2011-05-10 01:45:45 UTC; 39min ago
     Docs: man:systemd-networkd.service(8)
           man:rtnetlink(7)
   Listen: route 273 (Netlink)

May 10 01:45:45 localhost systemd[1]: Unit systemd-networkd.socket entered failed state.
Warning: Journal has been rotated since unit was started. Log output is incomplete or unavailable.

I should mention that NetworkManager is not installed nor is DHClient. Due to the fact that this was a minimal install I thought I'd show what processes are running:

ps -ax
  PID TTY      STAT   TIME COMMAND
    1 ?        Ss     0:09 /init
    2 ?        S      0:00 [kthreadd]
    3 ?        S      0:00 [ksoftirqd/0]
    5 ?        S<     0:00 [kworker/0:0H]
    7 ?        S      0:00 [migration/0]
    8 ?        S  /0]
   10 ?        S      0:00 [rcuob/1]
   11 ?        S      0:00 [rcuob/2]
   12 ?        S      0:00 [rcuob/3]
   13 ?        S      0:00 [rcu_sched]
   14 ?        S      0:00 [rcuos/0]
   15 ?        S      0:00 [rcuos/1]
   16 ?        S      0:00 [rcuos/2]
   17 ?        S      0:00 [rcuos/3]
   18 ?        S      0:00 [watchdog/0]
   19 ?        S      0:00 [watchdog/1]
   20 ?        S      0:00 [migration/1]
   21 ?        S      0:00 [ksoftirqd/1]
   23 ?        S<     0:00 [kworker/1:0H]
   24 ?        S<     0:00 [khelper]
   25 ?        S      0:00 [kdevtmpfs]
   26 ?        S<     0:00 [netns]
   27 ?        S<     0:00 [perf]
   28 ?        S<     0:00 [writeback]
   29 ?        S<     0:00 [kintegrityd]
   30 ?        S<     0:00 [bioset]
   31 ?        S<     0:00 [kblockd]
   32 ?        S<     0:00 [md]
   33 ?        S      0:00 [kworker/0:1]
   34 ?        S      0:00 [kworker/1:1]
   38 ?        S      0:00 [khungtaskd]
   39 ?        S      0:00 [kswapd0]
   40 ?        SN     0:00 [ksmd]
   41 ?        SN     0:00 [khugepaged]
   42 ?        S      0:00 [fsnotify_mark]
   43 ?        S<     0:00 [crypto]
   51 ?        S<     0:00 [kthrotld]
   54 ?        S<     0:00 [kmpath_rdacd]
   55 ?        S      0:00 [kworker/1:2]
   56 ?        S<     0:00 [kpsmoused]
   57 ?        S      0:00 [kworker/0:2]
   58 ?        S<     0:00 [ipv6_addrconf]
   77 ?        S<     0:00 [deferwq]
   89 ?        Ss     0:00 /usr/lib/systemd/systemd-journald
   96 ?        S<     0:00 [rpciod]
  109 ?        S      0:00 [kauditd]
  110 ?        Ss     0:00 /usr/sbin/lvmetad -f
  131 ?        Ss     0:00 /usr/lib/systemd/systemd-udevd
  160 ?        S<     0:00 [events_power_ef]
  164 ?        S<     0:00 [ata_sff]
  166 ?        S      0:17 [kworker/u8:3]
  167 ?        S      0:00 [scsi_eh_0]
  169 ?        S<     0:00 [scsi_tmf_0]
  172 ?        S      0:00 [scsi_eh_1]
  173 ?        S<     0:00 [scsi_tmf_1]
  174 ?        S      0:00 [kworker/u8:4]
  175 ?        S      0:00 [scsi_eh_2]
  176 ?        S<     0:00 [scsi_tmf_2]
  177 ?        S      0:00 [scsi_eh_3]
  178 ?        S<     0:00 [scsi_tmf_3]
  181 ?        S<     0:00 [kvm-irqfd-clean]
  208 ?        S<     0:00 [kworker/0:1H]
  209 ?        S<     0:00 [kworker/1:1H]
  213 ?        S      0:00 [jbd2/sda1-8]
  214 ?        S<     0:00 [ext4-rsv-conver]
  215 ?        S<     0:00 [ext4-unrsv-conv]
  235 ?        S<sl   0:00 /sbin/auditd -n
  260 ?        SNs    0:00 /usr/sbin/alsactl -s -n 19 -c -E ALSA_CONFIG_PATH=/et
  262 ?        SNsl   0:00 /usr/libexec/rtkit-daemon
  263 ?        Ss     0:00 /bin/dbus-daemon --system --address=systemd: --nofork
  268 ?        Ss     0:00 avahi-daemon: running [linux.local]
  269 ?        Ssl    0:00 /usr/bin/python -Es /usr/sbin/firewalld --nofork --no
  270 ?        Ss     0:00 /usr/lib/systemd/systemd-logind
  279 ?        Ss     0:00 /usr/sbin/gpm -m /dev/input/mice -t exps2
  280 ?        Ss     0:00 /usr/sbin/irqbalance --foreground
  281 ?        Ssl    0:00 /usr/sbin/rsyslogd -n
  282 ?        Ssl    0:00 /usr/sbin/gssproxy -D
  284 ?        S      0:00 avahi-daemon: chroot helper
  500 ?        Ss     0:00 /usr/sbin/sshd -D
  503 ?        Ssl    0:00 /usr/bin/python -Es /usr/sbin/tuned -l -P
  510 ?        Ssl    0:00 /usr/sbin/libvirtd
  512 ?        Ss     0:00 /usr/sbin/xinetd -stayalive -pidfile /var/run/xinetd.
  519 ?        Ss     0:00 /usr/sbin/crond -n
  546 tty1     Ss+    0:00 /sbin/agetty --noclear tty1 linux
  547 ?        Ss     0:00 login -- mini
  976 ?        Ssl    0:00 /usr/lib/polkit-1/polkitd --no-debug
 1022 ?        S      0:00 /sbin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/de
 1023 ?        S      0:00 /sbin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/de
 1025 ttyS0    Ss     0:00 -bash
 1057 ttyS0    S      0:00 su -
 1058 ttyS0    S      0:00 -bash
 1093 ?        Ss     0:00 /usr/sbin/anacron -s
15547 ttyS0    R+     0:00 ps -ax

One thing I find interesting is that /init is listed as PID 1 but ps -p 1 -o comm= shows that I'm running systemd. Also:

[root@localhost tmp]# pstree

systemd-+-agetty
        |-alsactl
        |-anacron
        |-auditd---{auditd}
        |-avahi-daemon---avahi-daemon
        |-crond
        |-dbus-daemon
        |-dnsmasq---dnsmasq
        |-firewalld---{firewalld}
        |-gpm
        |-gssproxy---5*[{gssproxy}]
        |-irqbalance
        |-libvirtd---15*[{libvirtd}]
        |-login---bash---su---bash---pstree
        |-lvmetad
        |-polkitd---5*[{polkitd}]
        |-rsyslogd---2*[{rsyslogd}]
        |-rtkit-daemon---2*[{rtkit-daemon}]
        |-sshd
        |-systemd-journal
        |-systemd-logind
        |-systemd-udevd
        |-tuned---4*[{tuned}]
        `-xinetd

Any ideas as to what I should do to get systemd-networkd.service and systemd-networkd.socket to load successfully would be greatly appreciated.

I have a minimal CentOS 7.2 installation on a small mini PC with 6 ethernet ports. I chose to exclude NetworkManager from the install as I would prefer to use the basic network service or switch to using systemd-networkd. However, I can't seem to get the network or systemd-networkd services to start.

    systemctl status network.service -l
��● network.service - LSB: Bring up/down networking
   Loaded: loaded (/etc/rc.d/init.d/network)
   Active: failed (Result: exit-code) since Tue 2011-05-10 00:01:22 UTC; 5min ago
     Docs: man:systemd-sysv-generator(8)
  Process: 25591 ExecStart=/etc/rc.d/init.d/network start (code=exited, status=1/FAILURE)

May 10 00:01:22 localhost network[25591]: RTNETLINK answers: File exists
May 10 00:01:22 localhost network[25591]: RTNETLINK answers: File exists
May 10 00:01:22 localhost network[25591]: RTNETLINK answers: File exists
May 10 00:01:22 localhost network[25591]: RTNETLINK answers: File exists
May 10 00:01:22 localhost network[25591]: RTNETLINK answers: File exists
May 10 00:01:22 localhost network[25591]: RTNETLINK answers: File exists
May 10 00:01:22 localhost systemd[1]: network.service: control process exited, code=exited status=1
May 10 00:01:22 localhost systemd[1]: Failed to start LSB: Bring up/down networking.
May 10 00:01:22 localhost systemd[1]: Unit network.service entered failed state.
May 10 00:01:22 localhost systemd[1]: network.service failed.

journalctl -xe -u network.service
    -- Logs begin at Tue 2011-05-10 00:00:40 UTC, end at Tue 2011-05-10 00:02:35 UTC. --
May 10 00:00:44 localhost systemd[1]: Starting LSB: Bring up/down networking...
-- Subject: Unit network.service has begun start-up
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit network.service has begun starting up.
May 10 00:00:44 localhost network[334]: Bringing up loopback interface:  [  OK  ]
May 10 00:00:45 localhost network[334]: Bringing up interface eth0:  ERROR    : [/etc/sysconfig/network-scripts/ifup-eth] Device eth
0 does not seem to be present, delaying initialization.
May 10 00:00:45 localhost network[334]: [FAILED]
May 10 00:00:45 localhost network[334]: Bringing up interface eth1:  ERROR    : [/etc/sysconfig/network-scripts/ifup-eth] Device eth
1 does not seem to be present, delaying initialization.
May 10 00:00:45 localhost /etc/sysconfig/network-scripts/ifup-eth[702]: Device eth1 does not seem to be present, delaying initializa
tion.
May 10 00:00:45 localhost network[334]: [FAILED]
May 10 00:00:45 localhost systemd[1]: network.service: control process exited, code=exited status=1
May 10 00:00:45 localhost systemd[1]: Failed to start LSB: Bring up/down networking.
-- Subject: Unit network.service has failed
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
-- 
-- Unit network.service has failed.
-- 
-- The result is failed.
May 10 00:00:45 localhost systemd[1]: Unit network.service entered failed state.
May 10 00:00:45 localhost systemd[1]: network.service failed.
May 10 00:01:20 localhost systemd[1]: Starting LSB: Bring up/down networking...

Here's dmesg | grep e1000e

    [root@localhost ~]# dmesg | grep eth
[    9.194339] e1000e 0000:00:19.0 eth0: (PCI Express:2.5GT/s:Width x1) 00:01:05:0f:2a:a0
[    9.202239] e1000e 0000:00:19.0 eth0: Intel(R) PRO/1000 Network Connection
[    9.209127] e1000e 0000:00:19.0 eth0: MAC: 7, PHY: 8, PBA No: FFFFFF-0FF
[    9.320640] e1000e 0000:04:00.0 eth1: registered PHC clock
[    9.320643] e1000e 0000:04:00.0 eth1: (PCI Express:2.5GT/s:Width x1) 00:30:59:08:18:53
[    9.320645] e1000e 0000:04:00.0 eth1: Intel(R) PRO/1000 Network Connection
[    9.320734] e1000e 0000:04:00.0 eth1: MAC: 3, PHY: 8, PBA No: FFFFFF-0FF
[    9.453298] e1000e 0000:05:00.0 eth2: registered PHC clock
[    9.458777] e1000e 0000:05:00.0 eth2: (PCI Express:2.5GT/s:Width x1) 00:30:59:08:18:54
[    9.466673] e1000e 0000:05:00.0 eth2: Intel(R) PRO/1000 Network Connection
[    9.473608] e1000e 0000:05:00.0 eth2: MAC: 3, PHY: 8, PBA No: FFFFFF-0FF
[    9.609123] e1000e 0000:06:00.0 eth3: registered PHC clock
[    9.609126] e1000e 0000:06:00.0 eth3: (PCI Express:2.5GT/s:Width x1) 00:30:59:08:18:55
[    9.609128] e1000e 0000:06:00.0 eth3: Intel(R) PRO/1000 Network Connection
[    9.609203] e1000e 0000:06:00.0 eth3: MAC: 3, PHY: 8, PBA No: FFFFFF-0FF
[    9.704211] e1000e 0000:07:00.0 eth4: registered PHC clock
[    9.704214] e1000e 0000:07:00.0 eth4: (PCI Express:2.5GT/s:Width x1) 00:30:59:08:18:56
[    9.704216] e1000e 0000:07:00.0 eth4: Intel(R) PRO/1000 Network Connection
[    9.704291] e1000e 0000:07:00.0 eth4: MAC: 3, PHY: 8, PBA No: FFFFFF-0FF
[    9.816322] e1000e 0000:08:00.0 eth5: registered PHC clock
[    9.816324] e1000e 0000:08:00.0 eth5: (PCI Express:2.5GT/s:Width x1) 00:01:05:0f:2a:a1
[    9.816326] e1000e 0000:08:00.0 eth5: Intel(R) PRO/1000 Network Connection
[    9.816483] e1000e 0000:08:00.0 eth5: MAC: 3, PHY: 8, PBA No: FFFFFF-0FF
[root@localhost ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: gre0@NONE: <NOARP> mtu 1476 qdisc noop state DOWN 
    link/gre 0.0.0.0 brd 0.0.0.0
3: gretap0@NONE: <BROADCAST,MULTICAST> mtu 1462 qdisc noop state DOWN qlen 1000
    link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
4: enp0s25: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000
    link/ether 00:01:05:0f:2a:a0 brd ff:ff:ff:ff:ff:ff
5: enp4s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000
    link/ether 00:30:59:08:18:53 brd ff:ff:ff:ff:ff:ff
6: enp5s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000
    link/ether 00:30:59:08:18:54 brd ff:ff:ff:ff:ff:ff
7: enp6s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000
    link/ether 00:30:59:08:18:55 brd ff:ff:ff:ff:ff:ff
8: enp7s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000
    link/ether 00:30:59:08:18:56 brd ff:ff:ff:ff:ff:ff
9: enp8s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000
    link/ether 00:01:05:0f:2a:a1 brd ff:ff:ff:ff:ff:ff
10: eth_bri: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN 
    link/ether ae:75:23:c7:e3:b6 brd ff:ff:ff:ff:ff:ff
    inet 129.193.148.1/24 brd 129.193.148.255 scope global eth_bri
       valid_lft forever preferred_lft forever
    inet6 fe80::ac75:23ff:fec7:e3b6/64 scope link 
       valid_lft forever preferred_lft forever

Journctl -u network.service seems to imply that there is no eth0, but from dmesg it shows that there are eth0 through eth5. however; when I issue ip addr you can see that they've all been renamed to the new style provided by systemd-udevd; enp0s25...etc.

There's another thread on here Can't start CentOS 7 "network" service that implies that dhcpclient service might be getting in the way. The answer to that thread suggests disabling the dhcpclient service. In my case, I don't have a dhcpclient running.

[root@localhost ~]# ps -ef | grep dhc
root      2506 23576  0 00:23 ttyS0    00:00:00 grep --color=auto dhc
[root@localhost ~]#