Estou executando algumas VMs do Ubuntu 16.04 na nuvem do Azure. Sempre que eu reinicio uma VM, tenho que configurar o gateway padrão manualmente.
O gateway deve ser definido pelo dhclient. Eu ativei a depuração e obtive isso:
root @ backend01: /etc/dhcp/dhclient-exit-hooks.d# cat /tmp/dhclient-script.debug
root@backend01:/etc/dhcp/dhclient-exit-hooks.d# cat /tmp/dhclient-script.debug
Thu Jun 2 17:18:33 UTC 2016: entering /etc/dhcp/dhclient-enter-hooks.d, dumping variables.
reason='PREINIT'
interface='eth0'
--------------------------
Thu Jun 2 17:18:33 UTC 2016: entering /etc/dhcp/dhclient-enter-hooks.d, dumping variables.
reason='REBOOT'
interface='eth0'
new_ip_address='10.10.0.13'
new_network_number='10.10.0.0'
new_subnet_mask='255.255.0.0'
new_broadcast_address='10.10.255.255'
new_routers='10.10.0.1'
new_rfc3442_classless_static_routes='0 10 10 0 1 32 168 63 129 16 10 10 0 1'
new_domain_name='azure-prod'
new_domain_search='azure-prod.'
new_domain_name_servers='10.11.0.250 10.11.0.251'
Portanto, a opção de roteadores está definida corretamente. Até mesmo o arquivo de aluguel mostra o valor correto:
lease {
interface "eth0";
fixed-address 10.10.0.13;
server-name "RD7CFE90879C98";
option subnet-mask 255.255.0.0;
option dhcp-lease-time 4294967295;
option routers 10.10.0.1;
option dhcp-message-type 5;
option dhcp-server-identifier 168.63.129.16;
option domain-name-servers 10.11.0.250,10.11.0.251;
option domain-search "azure-prod.";
option dhcp-renewal-time 4294967295;
option rfc3442-classless-static-routes 0,10,10,0,1,32,168,63,129,16,10,10,0,1;
option unknown-245 a8:3f:81:10;
option dhcp-rebinding-time 4294967295;
option domain-name "azure-prod";
renew 0 2152/07/09 23:41:47;
rebind 0 2152/07/09 23:41:47;
expire 0 2152/07/09 23:41:47;
}
É assim que meu /etc/dhcp/dhclient.conf parece:
option rfc3442-classless-static-routes code 121 = array of unsigned integer 8;
send host-name = gethostname();
request subnet-mask, broadcast-address, time-offset, routers,
domain-name, domain-name-servers, domain-search, host-name,
dhcp6.name-servers, dhcp6.domain-search, dhcp6.fqdn, dhcp6.sntp-servers,
netbios-name-servers, netbios-scope, interface-mtu,
rfc3442-classless-static-routes, ntp-servers;
timeout 300;
supersede domain-name "azure-prod";
supersede domain-search "azure-prod";
Por que o dhclient não define minha rota padrão?