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IP addresses from public IP block in my LAN
Block of 64 public IP's, how many usable?how to implement a network that communicates with the internet without NAT?Using a public IP for select hosts in a LANDo different nodes on a LAN share a public IPv6 address?How to bypass NAT for LAN to use Public IP addressess?Network Diagram for IPv6 LANBasic questions about Public IP addresses and used portsAccessing internal website from subnetAccess to a server behind the SonicWall from the LAN using Public IP addresses
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If I have NAT or PAT applied on edge router, Would it matter if I use IP addresses from public block in my LAN? And how?
ip nat lan
edited May 2 at 17:46
Ron Trunk
45.9k3 gold badges43 silver badges95 bronze badges
asked May 2 at 17:18
NisaarDeenAzeemNisaarDeenAzeem
212 bronze badges
add a comment
|
If I have NAT or PAT applied on edge router, Would it matter if I use IP addresses from public block in my LAN? And how?
ip nat lan
edited May 2 at 17:46
Ron Trunk
45.9k3 gold badges43 silver badges95 bronze badges
asked May 2 at 17:18
NisaarDeenAzeemNisaarDeenAzeem
212 bronze badges
2
Are they from a block you own and that's routed to your LAN? Then it would possibly make sense and you do not need NAT to route the IPs.
– allo
May 3 at 11:30
No, well, not owned. I see you answer below.
– NisaarDeenAzeem
May 10 at 10:49
add a comment
|
If I have NAT or PAT applied on edge router, Would it matter if I use IP addresses from public block in my LAN? And how?
ip nat lan
edited May 2 at 17:46
Ron Trunk
45.9k3 gold badges43 silver badges95 bronze badges
asked May 2 at 17:18
NisaarDeenAzeemNisaarDeenAzeem
212 bronze badges
If I have NAT or PAT applied on edge router, Would it matter if I use IP addresses from public block in my LAN? And how?
ip nat lan
ip nat lan
edited May 2 at 17:46
Ron Trunk
45.9k3 gold badges43 silver badges95 bronze badges
asked May 2 at 17:18
NisaarDeenAzeemNisaarDeenAzeem
212 bronze badges
edited May 2 at 17:46
Ron Trunk
45.9k3 gold badges43 silver badges95 bronze badges
asked May 2 at 17:18
NisaarDeenAzeemNisaarDeenAzeem
212 bronze badges
edited May 2 at 17:46
Ron Trunk
45.9k3 gold badges43 silver badges95 bronze badges
edited May 2 at 17:46
Ron Trunk
45.9k3 gold badges43 silver badges95 bronze badges
edited May 2 at 17:46
Ron Trunk
45.9k3 gold badges43 silver badges95 bronze badges
45.9k3 gold badges43 silver badges95 bronze badges
asked May 2 at 17:18
NisaarDeenAzeemNisaarDeenAzeem
212 bronze badges
asked May 2 at 17:18
NisaarDeenAzeemNisaarDeenAzeem
212 bronze badges
asked May 2 at 17:18
NisaarDeenAzeemNisaarDeenAzeem
212 bronze badges
212 bronze badges
2
Are they from a block you own and that's routed to your LAN? Then it would possibly make sense and you do not need NAT to route the IPs.
– allo
May 3 at 11:30
No, well, not owned. I see you answer below.
– NisaarDeenAzeem
May 10 at 10:49
add a comment
|
2
Are they from a block you own and that's routed to your LAN? Then it would possibly make sense and you do not need NAT to route the IPs.
– allo
May 3 at 11:30
No, well, not owned. I see you answer below.
– NisaarDeenAzeem
May 10 at 10:49
2
2
Are they from a block you own and that's routed to your LAN? Then it would possibly make sense and you do not need NAT to route the IPs.
– allo
May 3 at 11:30
Are they from a block you own and that's routed to your LAN? Then it would possibly make sense and you do not need NAT to route the IPs.
– allo
May 3 at 11:30
No, well, not owned. I see you answer below.
– NisaarDeenAzeem
May 10 at 10:49
No, well, not owned. I see you answer below.
– NisaarDeenAzeem
May 10 at 10:49
add a comment
|
2 Answers
2
active
oldest
votes
EDITED
I'm assuming you're considering using an IP block that is not registered to you. Otherwise, skip to the last paragraph.
Besides being a very poor practice, if you use public addresses on your internal network, that means that you can never reach hosts that use those real addresses. You may think you'll never need to reach servers in some other part of the world, but you'd be surprised at how often that happens.
BTW, if you don't use NAT, you're essentially hijacking someone else's addresses, and your ISP may disconnect you from the Internet (among other things).
The RFC 1918 addresses (10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16) should provide plenty of address space for your internal network.
If you are using your own IP block, then there's nothing wrong with using those addresses internally. It may possibly increase your security risks, but those can be mitigated by other means.
answered May 2 at 17:31
Ron TrunkRon Trunk
45.9k3 gold badges43 silver badges95 bronze badges
2
Also note that non-RFC1918 addresses used inside your network wreak havoc with many security monitoring/intrusion detection systems. As far as the appliances are concerned, those are internet addresses which means those are internet originated packets bouncing around your LAN. Alarm bells ensue.
– drxzcl
May 2 at 20:42
2
There's also the issue of reverse DNS lookups. For example, if you gave one of your computers the IP address172.217.14.196, it'll show up in various places with the namesea30s01-in-f4.1e100.net.
– Mark
May 2 at 20:52
2
Even if you use NAT, it's very possible to have a router/NAT/firewall configuration that will send your LAN packets using public addresses out to the internet.
– mtraceur
May 2 at 21:24
2
And of course, the fact that you can't access those hosts on the Internet is the reason it's a very poor practice.
– immibis
May 2 at 23:14
2
Although it's extremely unusual, there is a special case where this would be legitimate: your network has properly assigned "public" IP addresses and those are what you are using. And for some reason you're also using PAT/NAT, perhaps to cloak your internal structure, perhaps to merge with another organisation's addressing. I've never seen this, and don't expect to!
– jonathanjo
May 3 at 7:58
|
show 2 more comments
It matters in the situation that you do not need/want to reach those public IPs used.
If you use such IPs and then you, for example, want to access a site that has one of the IPs, it will not work, because your IP will resolve locally instead of going through your edge router and forward.
My company also uses such a system (it was implemented this way to be able to connect to other partner locations via EIGRP) and the corresponding IPs are assigned to China, so things should be fine as the company does not deal anything directly with something in hosted in China.
answered May 3 at 12:39
OvermindOvermind
1211 bronze badge
add a comment
|
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2 Answers
2
active
oldest
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2 Answers
2
active
oldest
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active
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active
oldest
votes
EDITED
I'm assuming you're considering using an IP block that is not registered to you. Otherwise, skip to the last paragraph.
Besides being a very poor practice, if you use public addresses on your internal network, that means that you can never reach hosts that use those real addresses. You may think you'll never need to reach servers in some other part of the world, but you'd be surprised at how often that happens.
BTW, if you don't use NAT, you're essentially hijacking someone else's addresses, and your ISP may disconnect you from the Internet (among other things).
The RFC 1918 addresses (10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16) should provide plenty of address space for your internal network.
If you are using your own IP block, then there's nothing wrong with using those addresses internally. It may possibly increase your security risks, but those can be mitigated by other means.
answered May 2 at 17:31
Ron TrunkRon Trunk
45.9k3 gold badges43 silver badges95 bronze badges
2
Also note that non-RFC1918 addresses used inside your network wreak havoc with many security monitoring/intrusion detection systems. As far as the appliances are concerned, those are internet addresses which means those are internet originated packets bouncing around your LAN. Alarm bells ensue.
– drxzcl
May 2 at 20:42
2
There's also the issue of reverse DNS lookups. For example, if you gave one of your computers the IP address172.217.14.196, it'll show up in various places with the namesea30s01-in-f4.1e100.net.
– Mark
May 2 at 20:52
2
Even if you use NAT, it's very possible to have a router/NAT/firewall configuration that will send your LAN packets using public addresses out to the internet.
– mtraceur
May 2 at 21:24
2
And of course, the fact that you can't access those hosts on the Internet is the reason it's a very poor practice.
– immibis
May 2 at 23:14
2
Although it's extremely unusual, there is a special case where this would be legitimate: your network has properly assigned "public" IP addresses and those are what you are using. And for some reason you're also using PAT/NAT, perhaps to cloak your internal structure, perhaps to merge with another organisation's addressing. I've never seen this, and don't expect to!
– jonathanjo
May 3 at 7:58
|
show 2 more comments
EDITED
I'm assuming you're considering using an IP block that is not registered to you. Otherwise, skip to the last paragraph.
Besides being a very poor practice, if you use public addresses on your internal network, that means that you can never reach hosts that use those real addresses. You may think you'll never need to reach servers in some other part of the world, but you'd be surprised at how often that happens.
BTW, if you don't use NAT, you're essentially hijacking someone else's addresses, and your ISP may disconnect you from the Internet (among other things).
The RFC 1918 addresses (10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16) should provide plenty of address space for your internal network.
If you are using your own IP block, then there's nothing wrong with using those addresses internally. It may possibly increase your security risks, but those can be mitigated by other means.
answered May 2 at 17:31
Ron TrunkRon Trunk
45.9k3 gold badges43 silver badges95 bronze badges
2
Also note that non-RFC1918 addresses used inside your network wreak havoc with many security monitoring/intrusion detection systems. As far as the appliances are concerned, those are internet addresses which means those are internet originated packets bouncing around your LAN. Alarm bells ensue.
– drxzcl
May 2 at 20:42
2
There's also the issue of reverse DNS lookups. For example, if you gave one of your computers the IP address172.217.14.196, it'll show up in various places with the namesea30s01-in-f4.1e100.net.
– Mark
May 2 at 20:52
2
Even if you use NAT, it's very possible to have a router/NAT/firewall configuration that will send your LAN packets using public addresses out to the internet.
– mtraceur
May 2 at 21:24
2
And of course, the fact that you can't access those hosts on the Internet is the reason it's a very poor practice.
– immibis
May 2 at 23:14
2
Although it's extremely unusual, there is a special case where this would be legitimate: your network has properly assigned "public" IP addresses and those are what you are using. And for some reason you're also using PAT/NAT, perhaps to cloak your internal structure, perhaps to merge with another organisation's addressing. I've never seen this, and don't expect to!
– jonathanjo
May 3 at 7:58
|
show 2 more comments
EDITED
I'm assuming you're considering using an IP block that is not registered to you. Otherwise, skip to the last paragraph.
Besides being a very poor practice, if you use public addresses on your internal network, that means that you can never reach hosts that use those real addresses. You may think you'll never need to reach servers in some other part of the world, but you'd be surprised at how often that happens.
BTW, if you don't use NAT, you're essentially hijacking someone else's addresses, and your ISP may disconnect you from the Internet (among other things).
The RFC 1918 addresses (10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16) should provide plenty of address space for your internal network.
If you are using your own IP block, then there's nothing wrong with using those addresses internally. It may possibly increase your security risks, but those can be mitigated by other means.
answered May 2 at 17:31
Ron TrunkRon Trunk
45.9k3 gold badges43 silver badges95 bronze badges
EDITED
I'm assuming you're considering using an IP block that is not registered to you. Otherwise, skip to the last paragraph.
Besides being a very poor practice, if you use public addresses on your internal network, that means that you can never reach hosts that use those real addresses. You may think you'll never need to reach servers in some other part of the world, but you'd be surprised at how often that happens.
BTW, if you don't use NAT, you're essentially hijacking someone else's addresses, and your ISP may disconnect you from the Internet (among other things).
The RFC 1918 addresses (10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16) should provide plenty of address space for your internal network.
If you are using your own IP block, then there's nothing wrong with using those addresses internally. It may possibly increase your security risks, but those can be mitigated by other means.
answered May 2 at 17:31
Ron TrunkRon Trunk
45.9k3 gold badges43 silver badges95 bronze badges
edited May 3 at 12:48
answered May 2 at 17:31
Ron TrunkRon Trunk
45.9k3 gold badges43 silver badges95 bronze badges
answered May 2 at 17:31
Ron TrunkRon Trunk
45.9k3 gold badges43 silver badges95 bronze badges
answered May 2 at 17:31
Ron TrunkRon Trunk
45.9k3 gold badges43 silver badges95 bronze badges
45.9k3 gold badges43 silver badges95 bronze badges
2
Also note that non-RFC1918 addresses used inside your network wreak havoc with many security monitoring/intrusion detection systems. As far as the appliances are concerned, those are internet addresses which means those are internet originated packets bouncing around your LAN. Alarm bells ensue.
– drxzcl
May 2 at 20:42
2
There's also the issue of reverse DNS lookups. For example, if you gave one of your computers the IP address172.217.14.196, it'll show up in various places with the namesea30s01-in-f4.1e100.net.
– Mark
May 2 at 20:52
2
Even if you use NAT, it's very possible to have a router/NAT/firewall configuration that will send your LAN packets using public addresses out to the internet.
– mtraceur
May 2 at 21:24
2
And of course, the fact that you can't access those hosts on the Internet is the reason it's a very poor practice.
– immibis
May 2 at 23:14
2
Although it's extremely unusual, there is a special case where this would be legitimate: your network has properly assigned "public" IP addresses and those are what you are using. And for some reason you're also using PAT/NAT, perhaps to cloak your internal structure, perhaps to merge with another organisation's addressing. I've never seen this, and don't expect to!
– jonathanjo
May 3 at 7:58
|
show 2 more comments
2
Also note that non-RFC1918 addresses used inside your network wreak havoc with many security monitoring/intrusion detection systems. As far as the appliances are concerned, those are internet addresses which means those are internet originated packets bouncing around your LAN. Alarm bells ensue.
– drxzcl
May 2 at 20:42
2
There's also the issue of reverse DNS lookups. For example, if you gave one of your computers the IP address172.217.14.196, it'll show up in various places with the namesea30s01-in-f4.1e100.net.
– Mark
May 2 at 20:52
2
Even if you use NAT, it's very possible to have a router/NAT/firewall configuration that will send your LAN packets using public addresses out to the internet.
– mtraceur
May 2 at 21:24
2
And of course, the fact that you can't access those hosts on the Internet is the reason it's a very poor practice.
– immibis
May 2 at 23:14
2
Although it's extremely unusual, there is a special case where this would be legitimate: your network has properly assigned "public" IP addresses and those are what you are using. And for some reason you're also using PAT/NAT, perhaps to cloak your internal structure, perhaps to merge with another organisation's addressing. I've never seen this, and don't expect to!
– jonathanjo
May 3 at 7:58
2
2
Also note that non-RFC1918 addresses used inside your network wreak havoc with many security monitoring/intrusion detection systems. As far as the appliances are concerned, those are internet addresses which means those are internet originated packets bouncing around your LAN. Alarm bells ensue.
– drxzcl
May 2 at 20:42
Also note that non-RFC1918 addresses used inside your network wreak havoc with many security monitoring/intrusion detection systems. As far as the appliances are concerned, those are internet addresses which means those are internet originated packets bouncing around your LAN. Alarm bells ensue.
– drxzcl
May 2 at 20:42
2
2
There's also the issue of reverse DNS lookups. For example, if you gave one of your computers the IP address
172.217.14.196, it'll show up in various places with the name sea30s01-in-f4.1e100.net.– Mark
May 2 at 20:52
There's also the issue of reverse DNS lookups. For example, if you gave one of your computers the IP address
172.217.14.196, it'll show up in various places with the name sea30s01-in-f4.1e100.net.– Mark
May 2 at 20:52
2
2
Even if you use NAT, it's very possible to have a router/NAT/firewall configuration that will send your LAN packets using public addresses out to the internet.
– mtraceur
May 2 at 21:24
Even if you use NAT, it's very possible to have a router/NAT/firewall configuration that will send your LAN packets using public addresses out to the internet.
– mtraceur
May 2 at 21:24
2
2
And of course, the fact that you can't access those hosts on the Internet is the reason it's a very poor practice.
– immibis
May 2 at 23:14
And of course, the fact that you can't access those hosts on the Internet is the reason it's a very poor practice.
– immibis
May 2 at 23:14
2
2
Although it's extremely unusual, there is a special case where this would be legitimate: your network has properly assigned "public" IP addresses and those are what you are using. And for some reason you're also using PAT/NAT, perhaps to cloak your internal structure, perhaps to merge with another organisation's addressing. I've never seen this, and don't expect to!
– jonathanjo
May 3 at 7:58
Although it's extremely unusual, there is a special case where this would be legitimate: your network has properly assigned "public" IP addresses and those are what you are using. And for some reason you're also using PAT/NAT, perhaps to cloak your internal structure, perhaps to merge with another organisation's addressing. I've never seen this, and don't expect to!
– jonathanjo
May 3 at 7:58
|
show 2 more comments
It matters in the situation that you do not need/want to reach those public IPs used.
If you use such IPs and then you, for example, want to access a site that has one of the IPs, it will not work, because your IP will resolve locally instead of going through your edge router and forward.
My company also uses such a system (it was implemented this way to be able to connect to other partner locations via EIGRP) and the corresponding IPs are assigned to China, so things should be fine as the company does not deal anything directly with something in hosted in China.
answered May 3 at 12:39
OvermindOvermind
1211 bronze badge
add a comment
|
It matters in the situation that you do not need/want to reach those public IPs used.
If you use such IPs and then you, for example, want to access a site that has one of the IPs, it will not work, because your IP will resolve locally instead of going through your edge router and forward.
My company also uses such a system (it was implemented this way to be able to connect to other partner locations via EIGRP) and the corresponding IPs are assigned to China, so things should be fine as the company does not deal anything directly with something in hosted in China.
answered May 3 at 12:39
OvermindOvermind
1211 bronze badge
add a comment
|
It matters in the situation that you do not need/want to reach those public IPs used.
If you use such IPs and then you, for example, want to access a site that has one of the IPs, it will not work, because your IP will resolve locally instead of going through your edge router and forward.
My company also uses such a system (it was implemented this way to be able to connect to other partner locations via EIGRP) and the corresponding IPs are assigned to China, so things should be fine as the company does not deal anything directly with something in hosted in China.
answered May 3 at 12:39
OvermindOvermind
1211 bronze badge
It matters in the situation that you do not need/want to reach those public IPs used.
If you use such IPs and then you, for example, want to access a site that has one of the IPs, it will not work, because your IP will resolve locally instead of going through your edge router and forward.
My company also uses such a system (it was implemented this way to be able to connect to other partner locations via EIGRP) and the corresponding IPs are assigned to China, so things should be fine as the company does not deal anything directly with something in hosted in China.
answered May 3 at 12:39
OvermindOvermind
1211 bronze badge
answered May 3 at 12:39
OvermindOvermind
1211 bronze badge
answered May 3 at 12:39
OvermindOvermind
1211 bronze badge
answered May 3 at 12:39
OvermindOvermind
1211 bronze badge
1211 bronze badge
add a comment
|
add a comment
|
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2
Are they from a block you own and that's routed to your LAN? Then it would possibly make sense and you do not need NAT to route the IPs.
– allo
May 3 at 11:30
No, well, not owned. I see you answer below.
– NisaarDeenAzeem
May 10 at 10:49