[Kea-users] Problems moving from ISC-DHCP to Kea

[Zenz, Thomas]

Hi,

Also you have to define if the reservations are in the pool or outside the pool.
I use a script to convert my reservations for each pool. My ISC-DHCP config is split into multiple files, so I search all files for Reservations in this subnet.

#!/bin/bash

# Usage: ./isc_to_kea.sh <ip-filter> <file1> [file2 ...]
# bash /usr/local/bin/isc_to_kea_ip.sh 10.102 $(find /etc/dhcpd/ -type f)

FILTER_IP="$1"
shift

echo "["

first=1
for file in "$@"; do
  # Nur reguläre Dateien verarbeiten
  [ -f "$file" ] || continue

  awk -v ip="$FILTER_IP" '
  BEGIN { block=""; inside=0 }
  {
    if ($0 ~ /^[[:space:]]*host[[:space:]]+[^{]+[[:space:]]*{[[:space:]]*$/) {
      block = $0 "\n"
      inside = 1
    } else if (inside) {
      block = block $0 "\n"
      if ($0 ~ /^[[:space:]]*}[[:space:]]*$/) {
        inside = 0
        if (block ~ "fixed-address[[:space:]]+" ip) {
          match(block, /host[[:space:]]+([^[:space:]]+)[[:space:]]*{/, m)
          hostname = m[1]
          match(block, /fixed-address[[:space:]]+([^;]+);/, m)
          ipaddr = m[1]
          match(block, /hardware ethernet[[:space:]]+([^;]+);/, m)
          hwaddr = m[1]
          match(block, /ddns-hostname[[:space:]]+"([^"]+)";/, m)
          ddns = m[1]

          if (!first) print ","
          first = 0

          print "  {"
          print "    \"hostname\": \"" hostname "\","
          print "    \"ip-address\": \"" ipaddr "\","
          print "    \"hw-address\": \"" hwaddr "\","
          print "    \"ddns-hostname\": \"" ddns "\","
          print "    \"boot-file-name\": \"\","
          print "    \"client-classes\": [],"
          print "    \"next-server\": \"0.0.0.0\","
          print "    \"option-data\": [],"
          print "    \"server-hostname\": \"\""
          print "  }"
        }
        block = ""
      }
    }
  }' "$file"
done

echo "]"


-----Ursprüngliche Nachricht-----
Von: Kea-users <kea-users-bounces at lists.isc.org> Im Auftrag von Francis Dupont
Gesendet: Donnerstag, 17. Juli 2025 09:47
An: Kea user's list <kea-users at lists.isc.org>; Mike Lieberman <mike at netwright.net>
Betreff: Re: [Kea-users] Problems moving from ISC-DHCP to Kea


HINWEIS: Externer Absender


Mike Lieberman writes:
> I have been using ISC-DHCP for years. I am a complete novice with Kea.
>
> I installed Kea 3.0.0 in a Debian 12 server. I migrated my large
> dhcp.conf via the ISC migration tool (successfully) and install the
> kea-dhcp4.conf file in the /etc/kea folder.
>
> I did run kea-admin -n with kea-dhcp4.conf and it took it. Testing
> showed that the service was live via dhcpdump.=C2=A0
>
> But the kea server is not serving up the reservation IP addresses that
> were migrated.

=> reservations are very different between ISC DHCP and Kea:
 - ISC DHCP reservations are not attached to a particular subnet (the subnet
  is found using the address when it exists)
 - Kea reservations are per subnet
Two additional details:
 - Kea has "global" reservations but they should not have an address even
  recent Kea versions try to find the corresponding subnet
 - an address can belongs to more than one subnet in Kea The result is the translation tool can't handle corner cases with reservations...

Regards

Francis Dupont <fdupont at isc.org>
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