Unix-/Linux Netz

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Hostadapter

• File
  • Host Network Manager
    • Create

Schaubild

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TCPDUMP auf rechter Firewall mit und ohne IP FORWARDING

ip_forward an

• echo 1 > /proc/sys/net/ip4/ip_forward

äussere Schnittstelle

• tcpdump -n -c 2 -i enp0s3 icmp

tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on enp0s3, link-type EN10MB (Ethernet), snapshot length 262144 bytes
09:12:55.057180 IP 10.0.21.21 > 10.0.22.21: ICMP echo request, id 11437, seq 500, length 64
09:12:55.057909 IP 10.0.22.21 > 10.0.21.21: ICMP echo reply, id 11437, seq 500, length 64
2 packets captured
2 packets received by filter 
0 packets dropped by kernel

innere Schnittstelle

• tcpdump -n -c 2 -i enp0s8 icmp

tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on enp0s8, link-type EN10MB (Ethernet), snapshot length 262144 bytes
09:12:55.057180 IP 10.0.21.21 > 10.0.22.21: ICMP echo request, id 11437, seq 500, length 64
09:12:55.057909 IP 10.0.22.21 > 10.0.21.21: ICMP echo reply, id 11437, seq 500, length 64
2 packets captured
2 packets received by filter
0 packets dropped by kernel

ip_forward aus

• echo 0 > /proc/sys/net/ip4/ip_forward

äussere Schnittstelle

• tcpdump -n -c 2 -i enp0s3 icmp

tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on enp0s3, link-type EN10MB (Ethernet), snapshot length 262144 bytes
09:13:54.225813 IP 10.0.21.21 > 10.0.22.21: ICMP echo request, id 11437, seq 559, length 64
09:13:55.249847 IP 10.0.21.21 > 10.0.22.21: ICMP echo request, id 11437, seq 560, length 64
2 packets captured
2 packets received by filter
0 packets dropped by kernel

innere Schnittstelle

• tcpdump -n -c 2 -i enp0s8 icmp

tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on enp0s8, link-type EN10MB (Ethernet), snapshot length 262144 bytes