[solved] one static client has two ips - 35030m [mostly]

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jay ray
DD-WRT Novice


Joined: 01 Apr 2017
Posts: 35

PostPosted: Sat Feb 24, 2018 2:47    Post subject: [solved] one static client has two ips - 35030m [mostly] Reply with quote
router: netgear r8000
firmware: DD-WRT v3.0-r35030M kongac (02/19/1Cool

I have an Intel NUC set with a static IP but its also getting a second IP from the DHCP pool. The NUC has been connected to my previous router for a year-ish via a single ethernet. Wireless on the NUC is and has always been off.

The Active Clients piece tells the story, really.



Once the NUC is connected, it receives its static IP: 192.168.17.9. Although instead of the name its been assigned in the services page, it gets the default *.

Unfortunately, the NUC also receives what appears to be a DHCP address, 192.168.17.108. Confusing me further, its hostname doesn't match what I assigned on the services page. I can only assume that DDWRT must be pulling from the /etc/hostname file on the NUC.

Another strange thing. While the x.x.x.108 address is within the bog-standard DD-WRT DHCP pool range, this 108 is always the one assigned, almost as if it was a static address. Every other device on my LAN is static, there have been no guests and certainly not eight of them. So why this number in partiular? Something's wrong in DHCPville but I don't know what.

I should mention that the router is a fresh out of the box r8000, and the DDWRT config is hand entered. Its been active only since yesterday about this time.

Does anyone know what went wrong or how to fix it? Thanks for looking.

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Netgear r8000 - DD-WRT v3.0-r46380


Last edited by jay ray on Sun Feb 25, 2018 21:13; edited 1 time in total
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<Kong>
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Joined: 15 Dec 2010
Posts: 4339
Location: Germany

PostPosted: Sat Feb 24, 2018 8:24    Post subject: Re: one static client has two ips - 35030m Reply with quote
jay ray wrote:
router: netgear r8000
firmware: DD-WRT v3.0-r35030M kongac (02/19/1Cool

I have an Intel NUC set with a static IP but its also getting a second IP from the DHCP pool. The NUC has been connected to my previous router for a year-ish via a single ethernet. Wireless on the NUC is and has always been off.

The Active Clients piece tells the story, really.



Once the NUC is connected, it receives its static IP: 192.168.17.9. Although instead of the name its been assigned in the services page, it gets the default *.

Unfortunately, the NUC also receives what appears to be a DHCP address, 192.168.17.108. Confusing me further, its hostname doesn't match what I assigned on the services page. I can only assume that DDWRT must be pulling from the /etc/hostname file on the NUC.

Another strange thing. While the x.x.x.108 address is within the bog-standard DD-WRT DHCP pool range, this 108 is always the one assigned, almost as if it was a static address. Every other device on my LAN is static, there have been no guests and certainly not eight of them. So why this number in partiular? Something's wrong in DHCPville but I don't know what.

I should mention that the router is a fresh out of the box r8000, and the DDWRT config is hand entered. Its been active only since yesterday about this time.

Does anyone know what went wrong or how to fix it? Thanks for looking.


Nothing wrong with dd-wrt you must be running linux on the nuc and at some point reconfigured it, changed netork cards or something like that, somehwre in your system you have old leases and while dhcp pulls a new ip it still uses the old ip, which it had before the change. Not sure which linux you have, but on the box I seen this before I had to stop dhcp, clear the lease dir and then start dhcp again.

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jay ray
DD-WRT Novice


Joined: 01 Apr 2017
Posts: 35

PostPosted: Sun Feb 25, 2018 2:03    Post subject: Reply with quote
Quote:
...just go to the Status / LAN tab, find the entry that you don't want in the DHCP clients list, and delete it using the rubbish bin in the far right column.


JXM,

Thanks for your suggestion. I should have included my troubleshooting steps along with the trouble. Very Happy Forgive me, I was more than a little, shall we say, lightheaded by the time I finished that post.

So yeah, the bin button was the first thing I tried. Alas, x.x.x.108 returned right away. I tried various permutations of rubbish bin/disconnects/reboots which all ended up back where I started: one client, two IPs.

I also tried disabling IPV6 on the router, the pihole, and the client. IPV6 had only been turned on two or three days before all this, solely because of the NTP problems. Turns out disabling IPV6 had no effect.


Quote:
Nothing wrong with dd-wrt you must be running linux on the nuc and at some point reconfigured it, changed netork cards or something like that, somehwre in your system you have old leases and while dhcp pulls a new ip it still uses the old ip, which it had before the change. Not sure which linux you have, but on the box I seen this before I had to stop dhcp, clear the lease dir and then start dhcp again.


KONG,

I think we are on to something here. This smells promising. I'm running ubuntu 17.10 on the NUC, which hosts openvpn and samba. The NUC was previously on static 192.18.17.4 and hadn't had IP issues like this before. I changed the IP to x.x.x.9 when I moved to the r8000 for network organization purposes. Its still on the same cable and NIC. The only thing that changed is the static IP and of course the new router.

At first, I received THREE IPs, but I learned about the /etc/network/interfaces file:

Code:
 interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback

#added the following in hopes to get opvn working
auto eno1
iface eno1 inet static
address 192.168.17.9
netmask 255.255.255.0
network 192.168.17.0
broadcast 192.168.17.255
gateway 192.168.17.1

# pre-up /etc/firewall-openvpn-rules.sh
# dns-nameservers=192.168.17.3 192.168.17.9


I changed the IP from x.x.x.4 to x.x.x.9 and solved that problem.

You mention a leases file. I'm still learning my way around linux. Where do I find this leases file to tweak the ip? I can't see why its permanent since previously the NUC was on x.x.x.4 and it had a dHCP lease for all of ~15 minutes while I transitioned to the new router.

_________________
Netgear r8000 - DD-WRT v3.0-r46380
jay ray
DD-WRT Novice


Joined: 01 Apr 2017
Posts: 35

PostPosted: Sun Feb 25, 2018 5:21    Post subject: Reply with quote
Okay. I found two lease files.

This first one was the only file in /var/lib/dhcp.

It read:

Code:

lease {
  interface "eno1";
  fixed-address 192.168.17.108;
  option subnet-mask 255.255.255.0;
  option routers 192.168.17.1;
  option dhcp-lease-time 86400;
  option dhcp-message-type 5;
  option domain-name-servers 192.168.17.3,192.168.17.4;
  option dhcp-server-identifier 192.168.17.1;
  option dhcp-renewal-time 43200;
  option broadcast-address 192.168.17.255;
  option dhcp-rebinding-time 75600;
  option host-name "nucvpn";
  option domain-name "hom";
  renew 0 2018/02/25 12:50:53;
  rebind 0 2018/02/25 23:22:16;
  expire 1 2018/02/26 02:22:16;
}


Which all looks correct except for the fixed-address IP, natch. I deleted it, rebooted the NUC and the file stays gone so far but it still has both IPs.

The second file was in /var/lib/dhcpcd5.
dhcpcd-eno1.lease

The output is strange. Half legible characters, the other half looks like its been ascii-redacted.

Code:

5▒▒▒▒l▒▒M0n▒Uc▒Sc56▒3Q▒:▒▒;'P▒▒▒▒▒hom
nucvp▒▒▒▒jayray@nucvpn:/var/lib/dhcpcd5$ PuTTY


I don't know what to make of this. Deleted this one too, but upon a reboot I've still got the same 2 IPs. This file is rewritten after a reboot.

I realize its looking like this is a Linux issue, not from DD WRT. Please don't feel obliged to reply. It just feels like we're close... I'll keep looking.

_________________
Netgear r8000 - DD-WRT v3.0-r46380
jay ray
DD-WRT Novice


Joined: 01 Apr 2017
Posts: 35

PostPosted: Sun Feb 25, 2018 7:14    Post subject: Reply with quote
Okay, fixed it. Thanks, Kong, for setting me on the right path.

I don't much understand the fix, but https://askubuntu.com/a/914708 this guy had the same problem as me. One answer seemed likelier than the rest, so I went for it.

Code:

systemctl stop dhcpcd
systemctl disable dhcpcd


It worked. Samba is back and so is OVPN and all is right with the world again. I still don't know what changed; all I did was plug the exact same device into a new router. And I have a nagging feeling that disabling dhcpcd will bite me later. All for another day.

Thanks again, Kong!

Now on to the next project: give an isolated guest network another go.

_________________
Netgear r8000 - DD-WRT v3.0-r46380
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