Nos servidores Ubuntu 16.04 e 18.04, no arquivo /var/log/syslog, muitas vezes há mensagens de origem marciana como:
Aug 23 06:42:51 scilit-solr kernel: [5417098.171549] IPv4: martian source 255.255.255.255 from 192.168.0.239, on dev bond0
Aug 23 06:42:51 scilit-solr kernel: [5417098.171565] ll header: 00000000: ff ff ff ff ff ff 00 8e f2 4e 0e 67 08 00 .........N.g..
Como descobrir quem está tentando se comunicar em uma sub-rede? Eu tentei executar:
sudo tcpdump -i bond0 host 192.168.0.239
E consegui isso:
06:46:41.750645 ARP, Request who-has 192.168.0.239 tell 192.168.0.239, length 46
06:46:41.750790 ARP, Request who-has 192.168.0.239 tell 192.168.0.239, length 46
06:46:41.754853 ARP, Request who-has 192.168.0.239 tell 192.168.0.239, length 46
06:46:41.754981 ARP, Request who-has 192.168.0.239 tell 192.168.0.239, length 46
06:46:41.759720 IP 192.168.0.239.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:8e:f2:4e:0e:67 (oui Unknown), length 253
06:46:41.759865 IP 192.168.0.239.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:8e:f2:4e:0e:67 (oui Unknown), length 253
06:46:46.081698 IP 192.168.0.239.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:8e:f2:4e:0e:67 (oui Unknown), length 253
06:46:46.081836 IP 192.168.0.239.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:8e:f2:4e:0e:67 (oui Unknown), length 253
06:46:52.414603 IP 192.168.0.239.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:8e:f2:4e:0e:67 (oui Unknown), length 253
06:46:52.414749 IP 192.168.0.239.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:8e:f2:4e:0e:67 (oui Unknown), length 253
06:47:03.750032 IP 192.168.0.239.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:8e:f2:4e:0e:67 (oui Unknown), length 253
06:47:03.750170 IP 192.168.0.239.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:8e:f2:4e:0e:67 (oui Unknown), length 253
06:47:26.089927 IP 192.168.0.239.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:8e:f2:4e:0e:67 (oui Unknown), length 253
06:47:26.090082 IP 192.168.0.239.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request from 00:8e:f2:4e:0e:67 (oui Unknown), length 253
O objetivo seria identificar o dispositivo que costuma enviar quem tem e corrigir seu IP e sub-rede.
Responder1
Consegui descobrir isso, não da melhor maneira, mas os resultados estão aí.
Alterei o endereço IP de uma das interfaces e tentei primeiro um login SSH, não funcionou. Em seguida, tentei curl e obtive uma página, era nosso switch Netgear GS716Tv2 com seu endereço IP configurado padrão. Vou trocá-lo em breve e o problema estará resolvido.