unifi controller block device - unblock grabs same IP
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For a break fix client, I put in a Unifi switch and wireless APs. Today I got a call that they couldn't print. After a few minutes I realize that there is a duplicate IP on the network. The copier guy used a static IP on the copier and put it in the DHCP range. He also went around and set up people with direct TCP/IP printing.
In the Unifi controller I see that an android device picked up the IP from the DHCP server. I hit the block link from Unifi and the copier starts pinging again and jobs start spitting out of the copier. I grabbed the MAC of the copier and set a reservation on the DHCP server. Then I decided I should probably enable the blocked android device.
I was expecting it to try to connect and grab a new IP, but it didn't. It tried to use the one that it had before. Short of tracking down the offending android device, is there another way to force it to grab a new IP? I might just wait a day and then enable it again since the user will probably take the device home and then when it reconnects it will reach out to the DHCP server again.
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@mike-davis
Don't know how to force that via a command because it's going to retain the IP for whatever you set the lease time to. I would set the lease time to something much lower temporarily and take that IP out of the DHCP range. It will fail the renewal eventually. -
Why not statically assign it an IP that is outside of the scope...
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I'm assuming it's a cell phone but maybe not
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@wirestyle22 said in unifi controller block device - unblock grabs same IP:
I'm assuming it's a cell phone
OK.. well in the cell phone case a DHCP reservation would fix that issue. . . then force a renewal from the DHCP server.
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@dustinb3403 said in unifi controller block device - unblock grabs same IP:
Why not statically assign it an IP that is outside of the scope...
In the case of the copier, I would have to visit every desktop to change the IP in the port of the local printer the copier guy set up. I'm lazy.
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@mike-davis said in unifi controller block device - unblock grabs same IP:
@dustinb3403 said in unifi controller block device - unblock grabs same IP:
Why not statically assign it an IP that is outside of the scope...
In the case of the copier, I would have to visit every desktop to change the IP in the port of the local printer the copier guy set up. I'm lazy.
But you get to charge the client for the time fixing his screw up. .
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@wirestyle22 said in unifi controller block device - unblock grabs same IP:
I'm assuming it's a cell phone but maybe not
The android device is likely a cell phone.
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@mike-davis said in unifi controller block device - unblock grabs same IP:
@dustinb3403 said in unifi controller block device - unblock grabs same IP:
Why not statically assign it an IP that is outside of the scope...
In the case of the copier, I would have to visit every desktop to change the IP in the port of the local printer the copier guy set up. I'm lazy.
Right. That's why I say reduce the lease time, let the lease time run out and remove that IP from the DHCP scope. Then just wait.
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@dustinb3403 said in unifi controller block device - unblock grabs same IP:
But you get to charge the client for the time fixing his screw up. .
That is true. And for a bonus round I get to explain to the client why what the copier guy did is wrong...
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@wirestyle22 said in unifi controller block device - unblock grabs same IP:
@mike-davis said in unifi controller block device - unblock grabs same IP:
@dustinb3403 said in unifi controller block device - unblock grabs same IP:
Why not statically assign it an IP that is outside of the scope...
In the case of the copier, I would have to visit every desktop to change the IP in the port of the local printer the copier guy set up. I'm lazy.
Right. That's why I say reduce the lease time, let the lease time run out and remove that IP from the DHCP scope. Then just wait.
Reducing the time will do jack shit. The device already knows its lease time and a new one on the server will not change that.
Just wait for lease roll then unblock it.
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@mike-davis After you unblocked it, did you force it to reconnect? That is a separate button I do believe.
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@dustinb3403 said in unifi controller block device - unblock grabs same IP:
@wirestyle22 said in unifi controller block device - unblock grabs same IP:
I'm assuming it's a cell phone
OK.. well in the cell phone case a DHCP reservation would fix that issue. . . then force a renewal from the DHCP server.
Wat?
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@jaredbusch said in unifi controller block device - unblock grabs same IP:
@mike-davis After you unblocked it, did you force it to reconnect? That is a separate button I do believe.
that shouldn't do anything either. The phone already has an IP for that network. So even forcing a reconnect to the SSID, I would expect phone to recognize the network and just use the same already assigned IP, of course, the Android folks could do whatever they want... so who knows until you try.
I agree with JB's earlier statement - leave it blocked until the time runs out. Then unblock and it will get a new IP.
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@dustinb3403 said in unifi controller block device - unblock grabs same IP:
@wirestyle22 said in unifi controller block device - unblock grabs same IP:
I'm assuming it's a cell phone
OK.. well in the cell phone case a DHCP reservation would fix that issue. . . then force a renewal from the DHCP server.
DHCP servers can't force clients to do anything.
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@dashrender said in unifi controller block device - unblock grabs same IP:
@dustinb3403 said in unifi controller block device - unblock grabs same IP:
@wirestyle22 said in unifi controller block device - unblock grabs same IP:
I'm assuming it's a cell phone
OK.. well in the cell phone case a DHCP reservation would fix that issue. . . then force a renewal from the DHCP server.
DHCP servers can't force clients to do anything.
You can delete the lease which forces the device to request a new IP. . .
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@dashrender said in unifi controller block device - unblock grabs same IP:
@jaredbusch said in unifi controller block device - unblock grabs same IP:
@mike-davis After you unblocked it, did you force it to reconnect? That is a separate button I do believe.
that shouldn't do anything either.
Depends on the device. Some devices will renegotiate the IP on reconnect.
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@dustinb3403 said in unifi controller block device - unblock grabs same IP:
@dashrender said in unifi controller block device - unblock grabs same IP:
@dustinb3403 said in unifi controller block device - unblock grabs same IP:
@wirestyle22 said in unifi controller block device - unblock grabs same IP:
I'm assuming it's a cell phone
OK.. well in the cell phone case a DHCP reservation would fix that issue. . . then force a renewal from the DHCP server.
DHCP servers can't force clients to do anything.
You can delete the lease which forces the device to request a new IP. . .
The forcing this list is talking about is on the client itself.. the DHCP server can't make the client do anything...
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Even though you can't initiate a remote renewal of the device's IP, it should phone home to the DHCP server if and when its network connection is disconnected for awhile and then reconnected, at which time it would pick up the new lease.
Normally when you disconnect/reconnect a network cable the client will phone back to DHCP since it no longer knows which LAN it is attached to. On WiFi devices, brief disconnection is by design not sufficient to trigger a refresh, but a longer outage should still prompt the client to request DHCP. I would guess that the if the client device is taken home for the evening and then returns in the morning (or even a lunch break, etc) it should pick up the new lease settings.
You could also attempt to force this by briefly disabling the SSID to which the client is currently connected (a couple minutes may do it).
