kleiner tipp: gib mal "strace ifconfig" ein.
die daten stammen nicht aus /proc, sondern aus:
socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 4
ioctl(4, SIOCGIFCONF, {80, {{"lo", {AF_INET, inet_addr("127.0.0.1")}}, {"eth0", {AF_INET, inet_addr("85.14.217.62")}}}}) = 0
ioctl(4, SIOCGIFFLAGS, {ifr_name="eth0", ifr_flags=IFF_UP|IFF_BROADCAST|IFF_RUNNING|IFF_MULTICAST}) = 0
ioctl(4, SIOCGIFHWADDR, {ifr_name="eth0", ifr_hwaddr=00:1d:60:24:0f:5b}) = 0
ioctl(4, SIOCGIFMETRIC, {ifr_name="eth0", ifr_metric=0}) = 0
ioctl(4, SIOCGIFMTU, {ifr_name="eth0", ifr_mtu=1500}) = 0
ioctl(4, SIOCGIFMAP, 0x7fff06e49350) = 0
ioctl(4, SIOCGIFMAP, 0x7fff06e49350) = 0
ioctl(4, SIOCGIFTXQLEN, 0x7fff06e49350) = 0
ioctl(4, SIOCGIFADDR, {ifr_name="eth0", ifr_addr={AF_INET, inet_addr("85.14.217.62")}}) = 0
ioctl(4, SIOCGIFDSTADDR, {ifr_name="eth0", ifr_dstaddr={AF_INET, inet_addr("85.14.217.62")}}) = 0
ioctl(4, SIOCGIFBRDADDR, {ifr_name="eth0", ifr_broadaddr={AF_INET, inet_addr("85.14.223.255")}}) = 0
ioctl(4, SIOCGIFNETMASK, {ifr_name="eth0", ifr_netmask={AF_INET, inet_addr("255.255.248.0")}}) = 0