What does routing an IP address mean? The 2019 Stack Overflow Developer Survey Results Are InWhat does the notation F0/0 and F0/1 mean in this diagram?Intra and internetwork routingWhen/Why to use OSPF?netstat -nr returning “0/1” — what does that mean?How does Logical Address works?How is anycast implemented?Should I always use “no ip address” command?Very confused with routingWhat is the use-case of including the IPv4 address in IPv6 address?Are the IPv6 address space and IPv4 address space completely disjoint?
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What does routing an IP address mean?
The 2019 Stack Overflow Developer Survey Results Are InWhat does the notation F0/0 and F0/1 mean in this diagram?Intra and internetwork routingWhen/Why to use OSPF?netstat -nr returning “0/1” — what does that mean?How does Logical Address works?How is anycast implemented?Should I always use “no ip address” command?Very confused with routingWhat is the use-case of including the IPv4 address in IPv6 address?Are the IPv6 address space and IPv4 address space completely disjoint?
From https://stackoverflow.com/a/40189197/156458
Blocking 0.0.0.0 makes no sense. In IPv4 it is never routed.
What does "routing" a IP address mean?
Why is it the reason that blocking 0.0.0.0 does not make sense?
Thanks.
routing ip-address
edited Mar 23 at 17:58
Zac67
32.7k22164
asked Mar 23 at 15:47
TimTim
665518
add a comment |
From https://stackoverflow.com/a/40189197/156458
Blocking 0.0.0.0 makes no sense. In IPv4 it is never routed.
What does "routing" a IP address mean?
Why is it the reason that blocking 0.0.0.0 does not make sense?
Thanks.
routing ip-address
edited Mar 23 at 17:58
Zac67
32.7k22164
asked Mar 23 at 15:47
TimTim
665518
2
You route packets, not addresses. The packets are routed based on the destination address in the packet header. The0.0.0.0address (actually, any address in the0.0.0.0/8network) is not allowed to be a destination address, so explicitly blocking that address doesn't really make sense.
– Ron Maupin♦
Mar 23 at 18:57
add a comment |
From https://stackoverflow.com/a/40189197/156458
Blocking 0.0.0.0 makes no sense. In IPv4 it is never routed.
What does "routing" a IP address mean?
Why is it the reason that blocking 0.0.0.0 does not make sense?
Thanks.
routing ip-address
edited Mar 23 at 17:58
Zac67
32.7k22164
asked Mar 23 at 15:47
TimTim
665518
From https://stackoverflow.com/a/40189197/156458
Blocking 0.0.0.0 makes no sense. In IPv4 it is never routed.
What does "routing" a IP address mean?
Why is it the reason that blocking 0.0.0.0 does not make sense?
Thanks.
routing ip-address
routing ip-address
edited Mar 23 at 17:58
Zac67
32.7k22164
asked Mar 23 at 15:47
TimTim
665518
edited Mar 23 at 17:58
Zac67
32.7k22164
asked Mar 23 at 15:47
TimTim
665518
edited Mar 23 at 17:58
Zac67
32.7k22164
edited Mar 23 at 17:58
Zac67
32.7k22164
edited Mar 23 at 17:58
Zac67
32.7k22164
32.7k22164
asked Mar 23 at 15:47
TimTim
665518
asked Mar 23 at 15:47
TimTim
665518
asked Mar 23 at 15:47
TimTim
665518
665518
2
You route packets, not addresses. The packets are routed based on the destination address in the packet header. The0.0.0.0address (actually, any address in the0.0.0.0/8network) is not allowed to be a destination address, so explicitly blocking that address doesn't really make sense.
– Ron Maupin♦
Mar 23 at 18:57
add a comment |
2
You route packets, not addresses. The packets are routed based on the destination address in the packet header. The0.0.0.0address (actually, any address in the0.0.0.0/8network) is not allowed to be a destination address, so explicitly blocking that address doesn't really make sense.
– Ron Maupin♦
Mar 23 at 18:57
2
2
You route packets, not addresses. The packets are routed based on the destination address in the packet header. The
0.0.0.0 address (actually, any address in the 0.0.0.0/8 network) is not allowed to be a destination address, so explicitly blocking that address doesn't really make sense.– Ron Maupin♦
Mar 23 at 18:57
You route packets, not addresses. The packets are routed based on the destination address in the packet header. The
0.0.0.0 address (actually, any address in the 0.0.0.0/8 network) is not allowed to be a destination address, so explicitly blocking that address doesn't really make sense.– Ron Maupin♦
Mar 23 at 18:57
add a comment |
1 Answer
1
active
oldest
votes
"Routing" means forwarding a packet based on its network-layer destination address, usually IPv4 or IPv6.
Routing is done by comparing the destination address to the entries in the local routing table and using the best (=longest prefix) match. The entry contains the next-hop gateway or the interface that the packet is then sent to/out of.
0.0.0.0/0 is the default route - because the prefix has zero length it matches any address. However, it is only selected when no other routing entry matches.
As IP address, 0.0.0.0 generally cannot be used (except as source address when configuring an interface, such as with DHCP).
answered Mar 23 at 16:33
Zac67Zac67
32.7k22164
Thanks. Does 0.0.0.0 (as an IP address) have two completely different meanings? (1) A process specifies its own unknown address to another process not in the same host, e.g. the DHCP example, and (2) a process specifies that it is listening on all the addresses on the local host, e.g. netstat shows mysql server is listening at::mysql(unix.stackexchange.com/q/508009/674)?
– Tim
Mar 23 at 16:42
In "Blocking 0.0.0.0 makes no sense. In IPv4 it is never routed", does 0.0.0.0 mean a IP address? Why is it never routed?
– Tim
Mar 23 at 16:45
Yes, 0.0.0.0 is also used when specifying "all local IP addresses" when allocating a BSD-style socket - however, this is host-specific and thus off-topic here.
– Zac67
Mar 23 at 16:46
You can't use 0.0.0.0 as destination address - so it's never routed.
– Zac67
Mar 23 at 16:56
Thanks. When a server uses 0.0.0.0 to indicate it is listening at all the IP adresses of local host, is 0.0.0.0 used as source address, destination address, or neither?
– Tim
Mar 23 at 21:46
|
show 4 more comments
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1 Answer
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"Routing" means forwarding a packet based on its network-layer destination address, usually IPv4 or IPv6.
Routing is done by comparing the destination address to the entries in the local routing table and using the best (=longest prefix) match. The entry contains the next-hop gateway or the interface that the packet is then sent to/out of.
0.0.0.0/0 is the default route - because the prefix has zero length it matches any address. However, it is only selected when no other routing entry matches.
As IP address, 0.0.0.0 generally cannot be used (except as source address when configuring an interface, such as with DHCP).
answered Mar 23 at 16:33
Zac67Zac67
32.7k22164
Thanks. Does 0.0.0.0 (as an IP address) have two completely different meanings? (1) A process specifies its own unknown address to another process not in the same host, e.g. the DHCP example, and (2) a process specifies that it is listening on all the addresses on the local host, e.g. netstat shows mysql server is listening at::mysql(unix.stackexchange.com/q/508009/674)?
– Tim
Mar 23 at 16:42
In "Blocking 0.0.0.0 makes no sense. In IPv4 it is never routed", does 0.0.0.0 mean a IP address? Why is it never routed?
– Tim
Mar 23 at 16:45
Yes, 0.0.0.0 is also used when specifying "all local IP addresses" when allocating a BSD-style socket - however, this is host-specific and thus off-topic here.
– Zac67
Mar 23 at 16:46
You can't use 0.0.0.0 as destination address - so it's never routed.
– Zac67
Mar 23 at 16:56
Thanks. When a server uses 0.0.0.0 to indicate it is listening at all the IP adresses of local host, is 0.0.0.0 used as source address, destination address, or neither?
– Tim
Mar 23 at 21:46
|
show 4 more comments
"Routing" means forwarding a packet based on its network-layer destination address, usually IPv4 or IPv6.
Routing is done by comparing the destination address to the entries in the local routing table and using the best (=longest prefix) match. The entry contains the next-hop gateway or the interface that the packet is then sent to/out of.
0.0.0.0/0 is the default route - because the prefix has zero length it matches any address. However, it is only selected when no other routing entry matches.
As IP address, 0.0.0.0 generally cannot be used (except as source address when configuring an interface, such as with DHCP).
answered Mar 23 at 16:33
Zac67Zac67
32.7k22164
Thanks. Does 0.0.0.0 (as an IP address) have two completely different meanings? (1) A process specifies its own unknown address to another process not in the same host, e.g. the DHCP example, and (2) a process specifies that it is listening on all the addresses on the local host, e.g. netstat shows mysql server is listening at::mysql(unix.stackexchange.com/q/508009/674)?
– Tim
Mar 23 at 16:42
In "Blocking 0.0.0.0 makes no sense. In IPv4 it is never routed", does 0.0.0.0 mean a IP address? Why is it never routed?
– Tim
Mar 23 at 16:45
Yes, 0.0.0.0 is also used when specifying "all local IP addresses" when allocating a BSD-style socket - however, this is host-specific and thus off-topic here.
– Zac67
Mar 23 at 16:46
You can't use 0.0.0.0 as destination address - so it's never routed.
– Zac67
Mar 23 at 16:56
Thanks. When a server uses 0.0.0.0 to indicate it is listening at all the IP adresses of local host, is 0.0.0.0 used as source address, destination address, or neither?
– Tim
Mar 23 at 21:46
|
show 4 more comments
"Routing" means forwarding a packet based on its network-layer destination address, usually IPv4 or IPv6.
Routing is done by comparing the destination address to the entries in the local routing table and using the best (=longest prefix) match. The entry contains the next-hop gateway or the interface that the packet is then sent to/out of.
0.0.0.0/0 is the default route - because the prefix has zero length it matches any address. However, it is only selected when no other routing entry matches.
As IP address, 0.0.0.0 generally cannot be used (except as source address when configuring an interface, such as with DHCP).
answered Mar 23 at 16:33
Zac67Zac67
32.7k22164
"Routing" means forwarding a packet based on its network-layer destination address, usually IPv4 or IPv6.
Routing is done by comparing the destination address to the entries in the local routing table and using the best (=longest prefix) match. The entry contains the next-hop gateway or the interface that the packet is then sent to/out of.
0.0.0.0/0 is the default route - because the prefix has zero length it matches any address. However, it is only selected when no other routing entry matches.
As IP address, 0.0.0.0 generally cannot be used (except as source address when configuring an interface, such as with DHCP).
answered Mar 23 at 16:33
Zac67Zac67
32.7k22164
edited Mar 23 at 16:43
answered Mar 23 at 16:33
Zac67Zac67
32.7k22164
answered Mar 23 at 16:33
Zac67Zac67
32.7k22164
answered Mar 23 at 16:33
Zac67Zac67
32.7k22164
32.7k22164
Thanks. Does 0.0.0.0 (as an IP address) have two completely different meanings? (1) A process specifies its own unknown address to another process not in the same host, e.g. the DHCP example, and (2) a process specifies that it is listening on all the addresses on the local host, e.g. netstat shows mysql server is listening at::mysql(unix.stackexchange.com/q/508009/674)?
– Tim
Mar 23 at 16:42
In "Blocking 0.0.0.0 makes no sense. In IPv4 it is never routed", does 0.0.0.0 mean a IP address? Why is it never routed?
– Tim
Mar 23 at 16:45
Yes, 0.0.0.0 is also used when specifying "all local IP addresses" when allocating a BSD-style socket - however, this is host-specific and thus off-topic here.
– Zac67
Mar 23 at 16:46
You can't use 0.0.0.0 as destination address - so it's never routed.
– Zac67
Mar 23 at 16:56
Thanks. When a server uses 0.0.0.0 to indicate it is listening at all the IP adresses of local host, is 0.0.0.0 used as source address, destination address, or neither?
– Tim
Mar 23 at 21:46
|
show 4 more comments
Thanks. Does 0.0.0.0 (as an IP address) have two completely different meanings? (1) A process specifies its own unknown address to another process not in the same host, e.g. the DHCP example, and (2) a process specifies that it is listening on all the addresses on the local host, e.g. netstat shows mysql server is listening at::mysql(unix.stackexchange.com/q/508009/674)?
– Tim
Mar 23 at 16:42
In "Blocking 0.0.0.0 makes no sense. In IPv4 it is never routed", does 0.0.0.0 mean a IP address? Why is it never routed?
– Tim
Mar 23 at 16:45
Yes, 0.0.0.0 is also used when specifying "all local IP addresses" when allocating a BSD-style socket - however, this is host-specific and thus off-topic here.
– Zac67
Mar 23 at 16:46
You can't use 0.0.0.0 as destination address - so it's never routed.
– Zac67
Mar 23 at 16:56
Thanks. When a server uses 0.0.0.0 to indicate it is listening at all the IP adresses of local host, is 0.0.0.0 used as source address, destination address, or neither?
– Tim
Mar 23 at 21:46
Thanks. Does 0.0.0.0 (as an IP address) have two completely different meanings? (1) A process specifies its own unknown address to another process not in the same host, e.g. the DHCP example, and (2) a process specifies that it is listening on all the addresses on the local host, e.g. netstat shows mysql server is listening at
::mysql (unix.stackexchange.com/q/508009/674)?– Tim
Mar 23 at 16:42
Thanks. Does 0.0.0.0 (as an IP address) have two completely different meanings? (1) A process specifies its own unknown address to another process not in the same host, e.g. the DHCP example, and (2) a process specifies that it is listening on all the addresses on the local host, e.g. netstat shows mysql server is listening at
::mysql (unix.stackexchange.com/q/508009/674)?– Tim
Mar 23 at 16:42
In "Blocking 0.0.0.0 makes no sense. In IPv4 it is never routed", does 0.0.0.0 mean a IP address? Why is it never routed?
– Tim
Mar 23 at 16:45
In "Blocking 0.0.0.0 makes no sense. In IPv4 it is never routed", does 0.0.0.0 mean a IP address? Why is it never routed?
– Tim
Mar 23 at 16:45
Yes, 0.0.0.0 is also used when specifying "all local IP addresses" when allocating a BSD-style socket - however, this is host-specific and thus off-topic here.
– Zac67
Mar 23 at 16:46
Yes, 0.0.0.0 is also used when specifying "all local IP addresses" when allocating a BSD-style socket - however, this is host-specific and thus off-topic here.
– Zac67
Mar 23 at 16:46
You can't use 0.0.0.0 as destination address - so it's never routed.
– Zac67
Mar 23 at 16:56
You can't use 0.0.0.0 as destination address - so it's never routed.
– Zac67
Mar 23 at 16:56
Thanks. When a server uses 0.0.0.0 to indicate it is listening at all the IP adresses of local host, is 0.0.0.0 used as source address, destination address, or neither?
– Tim
Mar 23 at 21:46
Thanks. When a server uses 0.0.0.0 to indicate it is listening at all the IP adresses of local host, is 0.0.0.0 used as source address, destination address, or neither?
– Tim
Mar 23 at 21:46
|
show 4 more comments
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2
You route packets, not addresses. The packets are routed based on the destination address in the packet header. The
0.0.0.0address (actually, any address in the0.0.0.0/8network) is not allowed to be a destination address, so explicitly blocking that address doesn't really make sense.– Ron Maupin♦
Mar 23 at 18:57