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I have a route table:

Kernel IP routing table
Destination       Gateway         Genmask         Flags Metric Ref    Use Iface
123.123.123.123   0.0.0.0         255.255.255.255 UH    0      0        0 vmbr0
123.123.123.0     0.0.0.0         255.255.255.224 U     0      0        0 vmbr0
0.0.0.0           123.123.123.1   0.0.0.0         UG    0      0        0 vmbr0

Does the

123.123.123.123   0.0.0.0         255.255.255.255 UH    0      0        0 vmbr0

mean, that there is no mediator (router) to this device (123.123.123.123), i.e. devices (current and 123.123.123.123) are directly connected? So the packet could be send directly to the device (123.123.123.123), with the help of arp routing table, extracting from there the MAC of 123.123.123.123?

Or am I misunderstanding that and it means: if destination IP is 123.123.123.123 look this table further and match the 0.0.0.0 rule, i.e. then route it to the 123.123.123.1?

It seems to be very basic, but I cannot find anything clearly, unambiguous explainable this staff. If there is some good articles, I would appreciate to read them.

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migrated from serverfault.com Jul 16 '13 at 21:45

This question came from our site for professional system and network administrators.

1 Answer 1

up vote 3 down vote accepted

Yes, 123.123.123.123 is directly connected to the same layer2-network and your host is configured to address it directly (with the help of a local arp lookup), not using a router.

The iproute2-tool is probably also worth a look:

/bin/ip route show

gives you another view on the routing table and

/bin/ip route get 132.123.123.123

also gives you the answer to "what interface, source IP address and gateway is being used when I'm trying to access 123.123.123.123".

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