How does setting a static IP on a mobile device prevent linux router from assigning that IP address?

How does setting a static IP on a linux Android mobile device prevent the
linux router from assigning that IP address to another device?

On any mobile device (iOS, Android, whatever), you can set up an FTP server
(eg ES File Explorer on Android) with a static IP address so that Windows
"My Network Places" has a permanent "shortcut" to the entire mobile device
file system (eg ftp://192.158.1.15:3721).

This is very useful, and I've been using it for a couple of weeks ever
since it was discussed here - because it effectively mounts the mobile
device as a network drive on Windows without adding any new software on
either Android or Windows.

The Android linux mobile device seems to retain the static IP address even
after multiple boots of the linux Android phone or of the Linux SOHO router
which is set up to serve DHCP addresses.

How does that work?
Why doesn't the linux router give another linux device the IP address
"192.168.1.15"?

It seems as if it works by "magic" but there must be some logic here.

How does setting the IP address to be static on the Android phone cause the
linux router to *accept* that static address permanently?





which can be set up in the mobile device connection settings
Android: Settings WiFi AP Modify network config IP settings
static (IP address = 192.158.1.15)

Tomos Davies wrote:
How does setting the IP address to be static on the Android phone cause the
linux router to *accept* that static address permanently?

It doesn't (permanently); it is still dynamic to the router.

For the same reason that when a cable modem releases its leased IP,
waits a short while, and then renews its lease with the DHCP, it gets
the exact same dyanmic IP back again. Normally.

However, you should be able to get the router to attach a particular LAN
IP to a particular MAC address device on the LAN.

--
Mike Easter

On 2017-04-11, Tomos Davies wrote:
How does setting a static IP on a linux Android mobile device prevent the
linux router from assigning that IP address to another device?

[...]

My guess is that your router's DHCP server originally gave your Android
device the dynamic IP number 192.168.1.15 (not 192.158.1.15 - that's a
publicly routable IP number) and still has it associated with that
device because it hasn't run out of unused IP numbers for allocating to
other devices on your LAN. That could happen easily if for example you
have six devices that connect to your LAN but the router is set to use a
range of 100 dynamic IP numbers. So when your Android device asks the
router 'can I be 192.168.1.15' then the router says 'OK'.

Dynamic IPs don't /have/ to change each time you disconnect and
reconnect.

You may be able to set the router to use a static IP for the Android
device and DHCP for everything else, if you want to be sure.

--
-- ^^^^^^^^^^
-- Whiskers
-- ~~~~~~~~~~

Whiskers wrote in
:

Dynamic IPs don't /have/ to change each time you disconnect and
reconnect.

You may be able to set the router to use a static IP for the Android
device and DHCP for everything else, if you want to be sure.

Usually, your router is acting as a DHCP host for the rest of the devices
on your network. In the setup for DHCP on the router, there is a setting
that lets you define the range of available DHCP addresses. Just set that
range so that some of the 255 addresses are not within the range of DHCP
addresses, then pick one of those outside that range to use as your static
IP

On Tue, 11 Apr 2017 22:10:39 -0000 (UTC), Tomos Davies
wrote:

How does setting a static IP on a linux Android mobile device prevent the
linux router from assigning that IP address to another device?

If you did it correctly, you assigned a static IP address
_outside_ the so-called DHCP range.
Any DHCP server, like in your router is set up to hand out
addresses in a specific range. Example:

network 192.168.1.0
netmask 255.255.255.0
gateway 192.168.1.1 (the address of the router on the LAN)
DHCP range 192.168.1.16 - 192.168.1.63

Now, if you decide to assign static addresses to any device, those
addresses have to be outside the DHCP range.

192.168.1.0 invalid, it is the address of the network as a whole
192.168.1.1 invalid, used by the router
192.168.1.2 valid, outside DHCP range
192.168.1.25 invalid, in the DHCP range
192.168.1.102 valid, outside DHCP range
192.168.1.255 invalid, broadcast address for this network


On any mobile device (iOS, Android, whatever), you can set up an FTP server
(eg ES File Explorer on Android) with a static IP address so that Windows
"My Network Places" has a permanent "shortcut" to the entire mobile device
file system (eg ftp://192.158.1.15:3721).

You probably mean 192.168.1.15 .

This is very useful, and I've been using it for a couple of weeks ever
since it was discussed here - because it effectively mounts the mobile
device as a network drive on Windows without adding any new software on
either Android or Windows.

The Android linux mobile device seems to retain the static IP address even
after multiple boots of the linux Android phone or of the Linux SOHO router
which is set up to serve DHCP addresses.

How does that work?
Why doesn't the linux router give another linux device the IP address
"192.168.1.15"?

It seems as if it works by "magic" but there must be some logic here.

How does setting the IP address to be static on the Android phone cause the
linux router to *accept* that static address permanently?


which can be set up in the mobile device connection settings
Android: Settings WiFi AP Modify network config IP settings
static (IP address = 192.158.1.15)

HTH
--
Regards,
Kees Nuyt

On 2017-04-12 00:10, Tomos Davies wrote:
How does setting a static IP on a linux Android mobile device prevent the
linux router from assigning that IP address to another device?

It doesn't.

There are three possibilities, though.

a) You accidentally assigned your phone an IP outside of the range
your router uses for DHCP addresses. Ie, the range dedicated to manually
given fixed addresses.

b) You accidentally assigned your phone the same IP as the router had
given it by DHCP.

c) You happen to have a router that before assigning an IP, first
pings that IP to see if it responds, then automatically removes that IP
from the pool of addresses it can give.



You should make sure that 'a' is true.


--
Cheers, Carlos.

On 2017-04-11, Tomos Davies wrote:
How does setting a static IP on a linux Android mobile device prevent the
linux router from assigning that IP address to another device?

It does not. You have been lucky, unless you go into the router to tell
it to reserve that IP address for that Mac address. dhcp will usually
reserve an IP for a mac for a little while, but there is no guarentee.
If your other machines are permanatly connected, there is no reason for
their IP addresses to change.



On any mobile device (iOS, Android, whatever), you can set up an FTP server
(eg ES File Explorer on Android) with a static IP address so that Windows
"My Network Places" has a permanent "shortcut" to the entire mobile device
file system (eg ftp://192.158.1.15:3721).

This is very useful, and I've been using it for a couple of weeks ever
since it was discussed here - because it effectively mounts the mobile
device as a network drive on Windows without adding any new software on
either Android or Windows.

The Android linux mobile device seems to retain the static IP address even
after multiple boots of the linux Android phone or of the Linux SOHO router
which is set up to serve DHCP addresses.

How does that work?
Why doesn't the linux router give another linux device the IP address
"192.168.1.15"?

It seems as if it works by "magic" but there must be some logic here.

How does setting the IP address to be static on the Android phone cause the
linux router to *accept* that static address permanently?

It does not.





which can be set up in the mobile device connection settings
Android: Settings WiFi AP Modify network config IP settings
static (IP address = 192.158.1.15)

On Tue, 11 Apr 2017 22:10:39 -0000 (UTC), Tomos Davies wrote:

How does setting a static IP on a linux Android mobile device prevent the
linux router from assigning that IP address to another device?

Each of the very few routers I've ever used has its 192.168.a.* address
range split into two halves: a lower range ( * running roughly 1-100) which
are treated as *fixed* addresses, *not* dynamically assignable; and an
upper range ( * roughly 101-253), dynamically assignable addresses. Here
the value "a" is either 0 or 1, depending on the router model/maker, and is
not variable.

It is *I* who can assign static addresses, from among the addresses in the
lower range; and it is the router who assigns the dynamic addresses, from
among the addresses in the upper range.

Addresses 192.168.a.254 and 192.168.a.255 are *not* assignable, not by me,
not by the router, as they play a fixed role already, as does 192.168.a.0 .

HTH, Stijn. Cheers, -- tlvp
--
Avant de repondre, jeter la poubelle, SVP.

On 04/11/2017 07:06 PM, Tim wrote:

[snip]

Just set that
range so that some of the 255 addresses are not within the range of DHCP
addresses, then pick one of those outside that range to use as your static
IP


Yes, put your static IP outside the DHCP pool.

BTW, that's "254 addresses" since both 0 and 255 (for the low octet)
can't be used. Also, the router itself will take one of these (often,
but not always, 1).

For my router, it uses 1 for itself, and the DHCP pool is 100-149. I use
addresses in the range 2-99.

--
Mark Lloyd
http://notstupid.us/

"If the Bible is telling the truth, then God is either untruthful or
incompetent. If God is truthful, then the Bible is either untruthful or
erroneous." [Rev. Donald Morgan, Atheologian]

On 04/11/2017 10:45 PM, tlvp wrote:

[snip]

Each of the very few routers I've ever used has its 192.168.a.* address
range split into two halves: a lower range ( * running roughly 1-100) which
are treated as *fixed* addresses, *not* dynamically assignable; and an
upper range ( * roughly 101-253), dynamically assignable addresses. Here
the value "a" is either 0 or 1, depending on the router model/maker, and is
not variable.

'a' can be any number 0-255. The only one 1 I'm sure I've seen is 15.

On my router, 'a' is 1, the router's address is 192.168.1.1 and the DHCP
pool is 100-149. Addresses 2-99 and 150-254 are available. This is
changeable, although I haven't had a need to.

It is *I* who can assign static addresses, from among the addresses in the
lower range; and it is the router who assigns the dynamic addresses, from
among the addresses in the upper range.

Addresses 192.168.a.254 and 192.168.a.255 are *not* assignable, not by me,
not by the router, as they play a fixed role already, as does 192.168.a.0 .

IIRC, I've used 192.168.a.254 and it worked fine. Maybe your router
itself is set to that.

HTH, Stijn. Cheers, -- tlvp



--
Mark Lloyd
http://notstupid.us/

"If the Bible is telling the truth, then God is either untruthful or
incompetent. If God is truthful, then the Bible is either untruthful or
erroneous." [Rev. Donald Morgan, Atheologian]

On 4/11/2017 3:22 PM, Mike Easter wrote:
Tomos Davies wrote:
How does setting the IP address to be static on the Android phone
cause the
linux router to *accept* that static address permanently?

It doesn't (permanently); it is still dynamic to the router.

For the same reason that when a cable modem releases its leased IP,
waits a short while, and then renews its lease with the DHCP, it gets
the exact same dyanmic IP back again. Normally.

However, you should be able to get the router to attach a particular LAN
IP to a particular MAC address device on the LAN.

Google "address reservation".
You don't want a fixed IP address on a phone.
You want it in DHCP so it will work anywhere.
Tell YOUR router to reserve/assign a FIXED IP address to
the MAC address of the phone.
Best of both worlds. Fixed at home, DHCP elsewhere.

In article , tlvp
wrote:


How does setting a static IP on a linux Android mobile device prevent the
linux router from assigning that IP address to another device?

Each of the very few routers I've ever used has its 192.168.a.* address
range split into two halves: a lower range ( * running roughly 1-100) which
are treated as *fixed* addresses, *not* dynamically assignable; and an
upper range ( * roughly 101-253), dynamically assignable addresses. Here
the value "a" is either 0 or 1, depending on the router model/maker, and is
not variable.

maybe by default it's that way, but you can change the dhcp range to
start/stop at whatever you want as well as the ip block.

It is *I* who can assign static addresses, from among the addresses in the
lower range; and it is the router who assigns the dynamic addresses, from
among the addresses in the upper range.

you can assign static addresses to whatever you want, inside or outside
of any range in the router.

Addresses 192.168.a.254 and 192.168.a.255 are *not* assignable, not by me,
not by the router, as they play a fixed role already, as does 192.168.a.0 .

254 is.

On 2017-04-12 06:43, Mark Lloyd wrote:
On 04/11/2017 10:45 PM, tlvp wrote:


Addresses 192.168.a.254 and 192.168.a.255 are *not* assignable, not by
me,
not by the router, as they play a fixed role already, as does
192.168.a.0 .

IIRC, I've used 192.168.a.254 and it worked fine. Maybe your router
itself is set to that.

It is 192.168.a.255 which is not usable, as it is the broadcast address.

--
Cheers, Carlos.

On 2017-04-12 06:51, mike wrote:
On 4/11/2017 3:22 PM, Mike Easter wrote:
Tomos Davies wrote:
How does setting the IP address to be static on the Android phone
cause the
linux router to *accept* that static address permanently?

It doesn't (permanently); it is still dynamic to the router.

For the same reason that when a cable modem releases its leased IP,
waits a short while, and then renews its lease with the DHCP, it gets
the exact same dyanmic IP back again. Normally.

However, you should be able to get the router to attach a particular LAN
IP to a particular MAC address device on the LAN.

Google "address reservation".
You don't want a fixed IP address on a phone.

Not true, he does.

You want it in DHCP so it will work anywhere.

It will work everywhere perfectly as it is.

Please remember that the setup only applies to his home WiFI. Other
WiFis get different configs.

--
Cheers, Carlos.

nospam wrote:
In article , tlvp
wrote:


How does setting a static IP on a linux Android mobile device prevent the
linux router from assigning that IP address to another device?

Each of the very few routers I've ever used has its 192.168.a.* address
range split into two halves: a lower range ( * running roughly 1-100) which
are treated as *fixed* addresses, *not* dynamically assignable; and an
upper range ( * roughly 101-253), dynamically assignable addresses. Here
the value "a" is either 0 or 1, depending on the router model/maker, and is
not variable.

maybe by default it's that way, but you can change the dhcp range to
start/stop at whatever you want as well as the ip block.

It is *I* who can assign static addresses, from among the addresses in the
lower range; and it is the router who assigns the dynamic addresses, from
among the addresses in the upper range.

you can assign static addresses to whatever you want, inside or outside
of any range in the router.

Addresses 192.168.a.254 and 192.168.a.255 are *not* assignable, not by me,
not by the router, as they play a fixed role already, as does 192.168.a.0 .

254 is.

254 is often the default router IP, they're usually either 192.168.1.1
or (less often) 192.168.1.254 if using the 192.168.1 block.

--
Chris Green
·