Ubuntu - Networking - ARP - Where are ARP entries stored in the system?

Access it from /proc file system.

cat /proc/net/arp

Result

P address       HW type     Flags       HW address            Mask     Device
192.168.1.102    0x1         0x2         d0:16:b4:b9:23:92     *        br0
192.168.1.10     0x1         0x2         18:e8:29:42:89:af     *        br0
192.168.1.1      0x1         0x2         00:e0:67:1f:ea:47     *        br0
192.168.1.5      0x1         0x2         24:5e:be:27:76:59     *        br0
192.168.1.2      0x1         0x2         44:a8:42:34:16:49     *        br0
192.168.1.113    0x1         0x2         02:d8:61:ea:5b:a1     *        br0
192.168.1.25     0x1         0x2         00:16:3e:13:ad:16     *        br0
192.168.1.100    0x1         0x2         34:64:a9:61:c4:64     *        br0
192.168.1.64     0x1         0x2         00:04:4b:5d:29:43     *        br0
192.168.1.8      0x1         0x2         80:61:5f:05:e5:fa     *        br0
192.168.1.26     0x1         0x2         00:a0:98:7c:01:b3     *        br0
192.168.1.41     0x1         0x2         ec:71:db:e7:81:f1     *        br0