subnet incorrectly detected for ISC-DHCP

[Wayne Workman]

r6455 when installing on CentOS 7 fully updated, DHCP fails.

Looking at the dhcpd.conf file that the installer built, the subnet mask is incorrect which means any calculations (like the network address or broadcast address) will also be incorrect because those calculations are dependent on the subnet mask being correct.

I’m thinking that wherever that info is pulled - it’s not pulling from the correct interface.

Here’s the config FOG produces currently for this machine:

# DHCP Server Configuration file\n#see /usr/share/doc/dhcp*/dhcpd.conf.sample
# This file was created by FOG
#Definition of PXE-specific options
# Code 1: Multicast IP Address of bootfile
# Code 2: UDP Port that client should monitor for MTFTP Responses
# Code 3: UDP Port that MTFTP servers are using to listen for MTFTP requests
# Code 4: Number of seconds a client must listen for activity before trying
#         to start a new MTFTP transfer
# Code 5: Number of seconds a client must listen before trying to restart
#         a MTFTP transfer
option space PXE;
option PXE.mtftp-ip code 1 = ip-address;
option PXE.mtftp-cport code 2 = unsigned integer 16;
option PXE.mtftp-sport code 3 = unsigned integer 16;
option PXE.mtftp-tmout code 4 = unsigned integer 8;
option PXE.mtftp-delay code 5 = unsigned integer 8;
option arch code 93 = unsigned integer 16;
use-host-decl-names on;
ddns-update-style interim;
ignore client-updates;
next-server 10.11.1.11;
# Specify subnet of ether device you do NOT want service.
# For systems with two or more ethernet devices.
# subnet 136.165.0.0 netmask 255.255.0.0 {}
subnet 10.11.1.0 netmask 255.255.255.0{
    option subnet-mask 255.255.255.0;
    range dynamic-bootp 10.11.1.10 10.11.15.254;
    default-lease-time 21600;
    max-lease-time 43200;
    option routers 10.11.15.254;
    option domain-name-servers 10.51.1.7;
    class "UEFI-32-1" {
        match if substring(option vendor-class-identifier, 0, 20) = "PXEClient:Arch:00006";
        filename "i386-efi/ipxe.efi";
    }
    class "UEFI-32-2" {
        match if substring(option vendor-class-identifier, 0, 20) = "PXEClient:Arch:00002";
        filename "i386-efi/ipxe.efi";
    }
    class "UEFI-64-1" {
        match if substring(option vendor-class-identifier, 0, 20) = "PXEClient:Arch:00007";
        filename "ipxe.efi";
    }
    class "UEFI-64-2" {
        match if substring(option vendor-class-identifier, 0, 20) = "PXEClient:Arch:00008";
        filename "ipxe.efi";
    }
    class "UEFI-64-3" {
        match if substring(option vendor-class-identifier, 0, 20) = "PXEClient:Arch:00009";
        filename "ipxe.efi";
    }
    class "Legacy" {
        match if substring(option vendor-class-identifier, 0, 20) = "PXEClient:Arch:00000";
        filename "undionly.kkpxe";
    }
}

Here is the output of 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: em1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 98:90:96:c5:11:e1 brd ff:ff:ff:ff:ff:ff
    inet 10.11.1.11/20 brd 10.11.15.255 scope global em1
       valid_lft forever preferred_lft forever
    inet6 fe80::9a90:96ff:fec5:11e1/64 scope link
       valid_lft forever preferred_lft forever
3: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN
    link/ether 52:54:00:2c:87:59 brd ff:ff:ff:ff:ff:ff
    inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
       valid_lft forever preferred_lft forever
4: virbr0-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast master virbr0 state DOWN qlen 500
    link/ether 52:54:00:2c:87:59 brd ff:ff:ff:ff:ff:ff

During installation, the installer recommended the IP address to be 192.168.122.1 (incorrect) and I manually typed in the correct address of 10.11.1.11

The installer also recommended virbr0 as the interface, and I changed that to em1.

I will do a pull request that fixes this later tonight.

In the meantime I’ve just configured ISC-DHCP on this machine manually, and told FOG no for DHCP.

[Wayne Workman]

Also - it’s noteworthy that the ending range that is calculated is calculated correctly.

[Wayne Workman]

I’ve patched this up in a suggested pull request. see here for details: https://forums.fogproject.org/topic/6732/install-update-your-database-blank-white-page