(random semi-opinionated comment: c'est rare to see this highish count of unconstructive et plain inaccurate answers et comments to a question)
In contrast to others here, I claim that votre request is actually assez elementary et has been supported in dnsmasq since version 2.46, IIRC. C'était le sole reason I switched from dd-wrt. After about a year of running OpenWRT, I now know there are actually plenty more reasons to switch, mais c'est beside le point.
Je suis running Backfire 10.04-rc4:
May 23 17:45:16 gateway dnsmasq[1925]: started, version 2.55 cachesize 150
My configuration:
$ cat /etc/config/dhcp
config 'dnsmasq'
option 'domainneeded' '1'
option 'boguspriv' '1'
option 'localise_queries' '1'
option 'rebind_protection' '1'
option 'rebind_localhost' '1'
option 'expandhosts' '1'
option 'authoritative' '1'
option 'readethers' '1'
option 'leasefile' '/tmp/dhcp.leases'
option 'resolvfile' '/tmp/resolv.conf.auto'
option 'enable_tftp' '1'
option 'domain' 'domain.net'
option 'local' '/domain.net/'
config 'dhcp' 'lan'
option 'interface' 'lan'
option 'start' '100'
option 'limit' '150'
option 'leasetime' 'infinite'
config 'dhcp' 'wan'
option 'interface' 'wan'
option 'ignore' '1'
option 'dynamicdhcp' '0'
config 'dhcp'
option 'interface' 'dmz'
option 'start' '100'
option 'limit' '150'
option 'leasetime' '12h'
config 'host'
option 'name' 'travelmate'
option 'mac' '00:11:22:33:44:55 aa:bb:cc:dd:ee:ff'
option 'ip' '192.168.1.111'
config 'host'
option 'name' 'mobilitymac'
option 'mac' '99:88:77:66:55:44 ff:ee:dd:cc:bb:aa'
option 'ip' '192.168.1.104'
Enjoy le seamless transition this setup provides, tous existing session stay alive si you ne take too long avec le switch.