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I have a virtual network configured in libvirt and configured to provide DHCP (via dnsmasq) but not configured to provide bootp information (see below), but when I boot an iPXE ISO and look at the traffic in wireshark I see that the DHCP service on that virtual network seems to be responding with a next-server parameter:

bootp.ip.server 192.168.122.1

This causes a problem because I'd like to use another server as a DHCP proxy to provide PXE information and for this to work libvirt's DHCP service has not not provide the next-server value.

How can I get libvirt virtual networks to not send that value?

EDIT: it seems that geeting libvirt's dnsmasq to ignore bootp requests can be accomplished by adding the folling statement to /var/lib/libvirt/dnsmasq/defaut.conf:

dhcp-ignore: bootp

...unfortunately thi file is overwritten when libvirt is restarted. Not sure if there's a configurable template where arguments for all virtual networks can be placed.

Virtual Network config:

<network connections='3'>
  <name>default</name>
  <uuid>59535def-2082-42f4-8e5e-a68f6f0fffbd</uuid>
  <forward mode='nat'>
    <nat>
      <port start='1024' end='65535'/>
    </nat>
  </forward>
  <bridge name='virbr0' stp='on' delay='0'/>
  <mac address='52:54:00:1c:02:0e'/>
  <ip address='192.168.122.1' netmask='255.255.255.0'>
    <dhcp>
      <range start='192.168.122.2' end='192.168.122.254'/>
    </dhcp>
  </ip>
</network>

DHCP request from iPXE:

16:04:59.394149 IP (tos 0x0, ttl 64, id 2237, offset 0, flags [none], proto UDP (17), length 441)
    0.0.0.0.bootpc > 255.255.255.255.bootps: [udp sum ok] BOOTP/DHCP, Request from 52:54:00:35:45:c5, length 413, xid 0xb665d069, secs 11, Flags [Broadcast] (0x8000)
  Client-Ethernet-Address 52:54:00:35:45:c5
  Vendor-rfc1048 Extensions
    Magic Cookie 0x63825363
    DHCP-Message Option 53, length 1: Request
    MSZ Option 57, length 2: 1472
    ARCH Option 93, length 2: 0
    NDI Option 94, length 3: 1.2.1
    Vendor-Class Option 60, length 32: "PXEClient:Arch:00000:UNDI:002001"
    CLASS Option 77, length 4: "iPXE"
    Parameter-Request Option 55, length 21: 
      Subnet-Mask, Default-Gateway, Domain-Name-Server, LOG
      Hostname, Domain-Name, RP, Vendor-Option
      Vendor-Class, TFTP, BF, Option 128
      Option 129, Option 130, Option 131, Option 132
      Option 133, Option 134, Option 135, Option 175
      Option 203
    T175 Option 175, length 51: 177.5.1.16.236.129.57.34.1.1.25.1.1.33.1.1.24.1.1.235.3.1.0.0.38.1.1.17.1.1.19.1.1.23.1.1.21.1.1.39.1.1.16.1.2.18.1.1.27.1.1
    Client-ID Option 61, length 7: ether 52:54:00:35:45:c5
    GUID Option 97, length 17: 0.36.246.109.48.115.66.98.75.170.28.144.120.91.142.203.164
    Server-ID Option 54, length 4: 192.168.122.1
    Requested-IP Option 50, length 4: 192.168.122.178
    END Option 255, length 0

DHCP response from libvirt:

16:04:59.487750 IP (tos 0xc0, ttl 64, id 11805, offset 0, flags [none], proto UDP (17), length 328)
192.168.122.1.bootps > 255.255.255.255.bootpc: [udp sum ok] BOOTP/DHCP, Reply, length 300, xid 0xb665d069, secs 11, Flags [Broadcast] (0x8000)
  Your-IP 192.168.122.178
  Server-IP 192.168.122.1
  Client-Ethernet-Address 52:54:00:35:45:c5
  Vendor-rfc1048 Extensions
    Magic Cookie 0x63825363
    DHCP-Message Option 53, length 1: ACK
    Server-ID Option 54, length 4: 192.168.122.1
    Lease-Time Option 51, length 4: 3600
    RN Option 58, length 4: 1800
    RB Option 59, length 4: 3150
    Subnet-Mask Option 1, length 4: 255.255.255.0
    BR Option 28, length 4: 192.168.122.255
    Default-Gateway Option 3, length 4: 192.168.122.1
    Domain-Name-Server Option 6, length 4: 192.168.122.1
    END Option 255, length 0
    PAD Option 0, length 0, occurs 8
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