Wie verbinde ich zwei Linux-Computer über einen dritten Linux-Computer?

Wie verbinde ich zwei Linux-Computer über einen dritten Linux-Computer?

Ich habe 3 virtuelle Maschinen über Oracle VirtualBox eingerichtet: Ubuntu, Fedora und CentOS. Die Ubuntu-Maschine ist wie folgt eingerichtet:

kuyu@ub16:~$ ifconfig
enp0s3    Link encap:Ethernet  HWaddr 08:00:27:ed:19:9f  
          inet addr:172.25.1.4  Bcast:172.25.1.255  Mask:255.255.255.0
          inet6 addr: fe80::7d42:e5b6:7818:df37/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:23245 errors:0 dropped:0 overruns:0 frame:0
          TX packets:18488 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:21373422 (21.3 MB)  TX bytes:3230755 (3.2 MB)

enp0s8    Link encap:Ethernet  HWaddr 08:00:27:a4:79:fe  
          inet6 addr: fe80::5d4e:ef97:3c34:f2b6/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1582 errors:0 dropped:0 overruns:0 frame:0
          TX packets:70 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:119897 (119.8 KB)  TX bytes:9194 (9.1 KB)

enp0s9    Link encap:Ethernet  HWaddr 08:00:27:3a:28:14  
          inet6 addr: fe80::118f:71e1:f2b2:f582/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1586 errors:0 dropped:0 overruns:0 frame:0
          TX packets:69 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:120766 (120.7 KB)  TX bytes:8852 (8.8 KB)

enp0s10   Link encap:Ethernet  HWaddr 08:00:27:3a:23:39  
          inet addr:10.0.3.4  Bcast:10.0.3.255  Mask:255.255.255.0
          inet6 addr: fe80::1013:fee6:cdd6:4ba4/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:16377 errors:0 dropped:0 overruns:0 frame:0
          TX packets:12869 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:15323241 (15.3 MB)  TX bytes:2256638 (2.2 MB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:2304 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2304 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1 
          RX bytes:292108 (292.1 KB)  TX bytes:292108 (292.1 KB)

kuyu@ub16:~$ route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         10.0.3.1        0.0.0.0         UG    100    0        0 enp0s10
default         172.25.1.1      0.0.0.0         UG    101    0        0 enp0s3
10.0.3.0        *               255.255.255.0   U     100    0        0 enp0s10
link-local      *               255.255.0.0     U     1000   0        0 enp0s10
172.25.1.0      *               255.255.255.0   U     100    0        0 enp0s3

Die Fedora-Maschine ist wie folgt eingerichtet:

[kuyu@localhost ~]$ ifconfig
enp0s3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
    inet 10.0.2.15  netmask 255.255.255.0  broadcast 10.0.2.255
    inet6 fe80::a06b:59f9:ecd2:5f4f  prefixlen 64  scopeid 0x20<link>
    ether 08:00:27:cc:b4:fe  txqueuelen 1000  (Ethernet)
    RX packets 15606  bytes 10210208 (9.7 MiB)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 10377  bytes 1378129 (1.3 MiB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

enp0s8: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
    inet 10.0.3.5  netmask 255.255.255.0  broadcast 10.0.3.255
    inet6 fe80::5081:a65:f591:5587  prefixlen 64  scopeid 0x20<link>
    ether 08:00:27:10:4b:c6  txqueuelen 1000  (Ethernet)
    RX packets 185  bytes 27128 (26.4 KiB)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 314  bytes 44983 (43.9 KiB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

enp0s9: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
    inet 192.168.2.5  netmask 255.255.255.0  broadcast 192.168.2.255
    inet6 fe80::ea6c:3aa1:5fc9:bdff  prefixlen 64  scopeid 0x20<link>
    ether 08:00:27:e1:62:f4  txqueuelen 1000  (Ethernet)
    RX packets 62  bytes 12502 (12.2 KiB)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 234  bytes 34491 (33.6 KiB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
    inet 127.0.0.1  netmask 255.0.0.0
    inet6 ::1  prefixlen 128  scopeid 0x10<host>
    loop  txqueuelen 1000  (Local Loopback)
    RX packets 36  bytes 3112 (3.0 KiB)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 36  bytes 3112 (3.0 KiB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

virbr0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
    inet 192.168.122.1  netmask 255.255.255.0  broadcast 192.168.122.255
    ether 00:00:00:00:00:00  txqueuelen 1000  (Ethernet)
    RX packets 0  bytes 0 (0.0 B)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 0  bytes 0 (0.0 B)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

[kuyu@localhost ~]$ route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         gateway         0.0.0.0         UG    100    0        0 enp0s3
default         gateway         0.0.0.0         UG    101    0        0 enp0s9
default         gateway         0.0.0.0         UG    102    0        0 enp0s8
10.0.2.0        0.0.0.0         255.255.255.0   U     100    0        0 enp0s3
10.0.3.0        0.0.0.0         255.255.255.0   U     100    0        0 enp0s8
192.168.2.0     0.0.0.0         255.255.255.0   U     100    0        0 enp0s9
192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0

Die CentOS-Maschine ist wie folgt eingerichtet:

[kuyu@localhost ~]$ ifconfig
enp0s3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
    inet 172.25.1.5  netmask 255.255.255.0  broadcast 172.25.1.255
    inet6 fe80::1f36:5e13:45ae:b7d1  prefixlen 64  scopeid 0x20<link>
    ether 08:00:27:f4:fd:91  txqueuelen 1000  (Ethernet)
    RX packets 15070  bytes 21673274 (20.6 MiB)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 7401  bytes 471787 (460.7 KiB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

enp0s8: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
    inet6 fe80::bd87:67c1:8b39:f511  prefixlen 64  scopeid 0x20<link>
    ether 08:00:27:30:f3:fa  txqueuelen 1000  (Ethernet)
    RX packets 1442  bytes 107149 (104.6 KiB)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 56  bytes 6524 (6.3 KiB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

enp0s9: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
    inet6 fe80::e6a5:62c4:3dfa:b841  prefixlen 64  scopeid 0x20<link>
    ether 08:00:27:b9:cf:71  txqueuelen 1000  (Ethernet)
    RX packets 1403  bytes 102963 (100.5 KiB)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 17  bytes 2954 (2.8 KiB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

enp0s10: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
    inet 192.168.2.4  netmask 255.255.255.0  broadcast 192.168.2.255
    inet6 fe80::3c3e:1a03:e554:514d  prefixlen 64  scopeid 0x20<link>
    ether 08:00:27:bd:1f:4a  txqueuelen 1000  (Ethernet)
    RX packets 131  bytes 23156 (22.6 KiB)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 339  bytes 57279 (55.9 KiB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
    inet 127.0.0.1  netmask 255.0.0.0
    inet6 ::1  prefixlen 128  scopeid 0x10<host>
    loop  txqueuelen 1  (Local Loopback)
    RX packets 134  bytes 11636 (11.3 KiB)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 134  bytes 11636 (11.3 KiB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

virbr0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
    inet 192.168.122.1  netmask 255.255.255.0  broadcast 192.168.122.255
    ether 52:54:00:bb:2b:56  txqueuelen 1000  (Ethernet)
    RX packets 0  bytes 0 (0.0 B)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 0  bytes 0 (0.0 B)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

[kuyu@localhost ~]$ route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         gateway         0.0.0.0         UG    100    0        0 enp0s3
default         gateway         0.0.0.0         UG    101    0        0 enp0s10
172.25.1.0      0.0.0.0         255.255.255.0   U     100    0        0 enp0s3
192.168.2.0     0.0.0.0         255.255.255.0   U     100    0        0 enp0s10
192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0

Das Routing ist in der Fedora-Maschine aktiviert:

[kuyu@localhost ~]$ sudo sysctl -p /etc/sysctl.conf
net.ipv4.ip_forward = 1

Die Ubuntu-Maschine kann die Fedora-Maschine anpingen:

kuyu@ub16:~$ ping 10.0.3.5
PING 10.0.3.5 (10.0.3.5) 56(84) bytes of data.
64 bytes from 10.0.3.5: icmp_seq=1 ttl=64 time=2.39 ms
64 bytes from 10.0.3.5: icmp_seq=2 ttl=64 time=1.53 ms

Ebenso kann die CentOS-Maschine die Fedora-Maschine anpingen:

[kuyu@localhost ~]$ ping 192.168.2.5
PING 192.168.2.5 (192.168.2.5) 56(84) bytes of data.
64 bytes from 192.168.2.5: icmp_seq=1 ttl=64 time=1.63 ms
64 bytes from 192.168.2.5: icmp_seq=2 ttl=64 time=1.14 ms
64 bytes from 192.168.2.5: icmp_seq=3 ttl=64 time=1.42 ms

Die Ubuntu-Maschine kann die CentOS-Maschine jedoch nicht über die Fedora-Maschine anpingen:

kuyu@ub16:~$ ping 192.168.2.4
PING 192.168.2.4 (192.168.2.4) 56(84) bytes of data.
^C
--- 192.168.2.4 ping statistics ---
5 packets transmitted, 0 received, 100% packet loss, time 4050ms

Ebenso kann die CentOS-Maschine die Ubuntu-Maschine nicht über die Fedora-Maschine anpingen:

[kuyu@localhost ~]$ ping 10.0.3.4
PING 10.0.3.4 (10.0.3.4) 56(84) bytes of data.
^C
--- 10.0.3.4 ping statistics ---
4 packets transmitted, 0 received, 100% packet loss, time 3004ms

Meine Frage lautet: Wie korrigiere ich die Maschinenkonfigurationen, sodass die Ubuntu-Maschine die CentOS-Maschine über die Fedora-Maschine anpingen kann (und umgekehrt)?

Antwort1

Es ist möglich/wahrscheinlich, dass Ihre Fedora-Box standardmäßig über eine Firewall verfügt, die die Weiterleitung von Paketen verhindert.

Versuchen Sie zu laufen

/sbin/iptables -I WEITER -j AKZEPTIEREN

Um die Weiterleitung über dieses Postfach zu ermöglichen.

Wenn das nicht funktioniert, würde ich tcpdump ausschalten (und dann einen Ping zwischen den Boxen starten und sehen, wo es hängen bleibt)

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