[user@debian8:~]$ sudo tcpdump -i eth1 -n icmp
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth1, link-type EN10MB (Ethernet), capture size 96 bytes
16:55:06.718093 IP 192.168.18.157 > 213.180.204.8: ICMP echo request, id 57617, seq 508, length 64
16:55:08.521985 IP 192.168.18.157 > 213.180.204.8: ICMP echo request, id 57617, seq 509, length 64
16:55:10.318978 IP 192.168.18.157 > 213.180.204.8: ICMP echo request, id 57617, seq 510, length 64
16:55:12.122994 IP 192.168.18.157 > 213.180.204.8: ICMP echo request, id 57617, seq 511, length 64
16:55:13.927650 IP 192.168.18.157 > 213.180.204.8: ICMP echo request, id 57617, seq 512, length 64
5 packets captured
5 packets received by filter
0 packets dropped by kernel
error: "Operation not permitted" reading key "net.ipv6.route.flush"
error: "Operation not permitted" reading key "net.ipv4.route.flush"
net.ipv6.conf.eth2.forwarding = 0
net.ipv6.conf.eth1.forwarding = 0
net.ipv6.conf.default.forwarding = 0
net.ipv6.conf.all.forwarding = 0
net.ipv6.conf.eth0.forwarding = 0
net.ipv6.conf.lo.forwarding = 0
net.ipv4.conf.eth2.mc_forwarding = 0
net.ipv4.conf.eth2.forwarding = 0
net.ipv4.conf.eth1.mc_forwarding = 0
net.ipv4.conf.eth1.forwarding = 0
net.ipv4.conf.eth0.mc_forwarding = 0
net.ipv4.conf.eth0.forwarding = 0
net.ipv4.conf.lo.mc_forwarding = 0
net.ipv4.conf.lo.forwarding = 0
net.ipv4.conf.default.mc_forwarding = 0
net.ipv4.conf.default.forwarding = 0
net.ipv4.conf.all.mc_forwarding = 0
net.ipv4.conf.all.forwarding = 0
net.ipv4.ip_forward = 0