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I have a Linksys WRT54GL router with Tomato installed on it.

enter image description here

My network configuration requires me to disable the DHCP server on the router. After disabling it, I do not know the IP of the router because it isn't my default gateway anymore. Now it is impossible to change settings (e.g. wireless password).

Any idea how to access the router?

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  • 1
    The router's IP address should still be the same as it was before. If you knew it's address earlier, that's still its address
    – Dr.Ping
    Aug 11, 2016 at 16:51

10 Answers 10

7

DHCP server does not necessarily mean default gateway.

If you are not using the DHCP server on your router, you need to either

  • set up another DHCP server on another computer or something else somewhere
  • assign IPs manually to all devices

Clients reach the DHCP server through broadcasts, i.e. traffic that is set to reach all nodes on your network. So nothing needs to know the IP of your DHCP server as long as the DHCP server is listening on something that is in the same subnet as the rest of your network.

Your DHCP server should be configured to hand out the router's IP as the default gateway.

Per your situation, if all you did was disable the DHCP server, the IP of the router probably didn't change and you can still use the same IP to get to it. If you do NOT have a DHCP server elsewhere on your network, try setting your IP to 192.168.X.44 subnet mask 255.255.255.0 - X is probably going to be 0 or 1 - then you can probably reach your router at 192.168.X.1 or 192.168.X.254.

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  • I don;t have access to the DHCP server; How do I know the IP of the router?
    – Adam Matan
    Mar 10, 2012 at 15:35
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    Just made an edit. It probably didn't change from the last time you set it. Typical default IPs of routers are 192.168.0.1, 192.168.0.254 , 192.168.1.1, 192.168.1.254.
    – LawrenceC
    Mar 10, 2012 at 16:10
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Best bet: Reset the router. The DHCP will turn back on and you can then connect. Credentials are probably admin/admin. If the DCHP was off, you probably weren't using it for much more than the wifi function, so there won't be many settings to reconfigure.

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  • You misunderstood. Having DHCP disabled is a REQUIREMENT in OP's setup. Having to reset the router to re-enable DHCP and then disable it again every time you need to make even the tiniest configuration change is completely unviable. Nov 20, 2021 at 12:36
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Try doing a 30 30 30 reset.

Follow these steps to perform a router hard reset:

  1. When the unit is powered on, hold down its reset button for 30 seconds.
  2. While still holding down the reset button, unplug the router from power and hold for an additional 30 seconds.
  3. Still holding down the reset button, turn on power to the router again and hold for 30 more seconds.
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  • Can you explain how to accomplish that?
    – fixer1234
    Aug 10, 2016 at 4:28
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in Ipv4 properities set ip manually.

  1. Ip address has to start the same as router ip except for last number (has to be different, usually higher).
  2. Mask is set automatically.
  3. Gate ip is your router ip.
  4. the first DNS is again your router ip.
  5. alternative DNS can set randomly (for examle google DNS 8.8.8.8)

Then just go to your browser and write your router ip to get to its setting

p.s. You can find router ip in command line by writing ipconfig - gate ip is ip of your router.

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    Welcome to Super User! Please read the question again carefully. Your answer does not answer the original question. He doesn't know the router IP so your instructions don't make any sense.
    – DavidPostill
    May 31, 2016 at 11:18
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    These sounds like instructions you would follow before disabling DHCP on the router. Then once DHCP is disabled, you know the static IP address you set for router. Sep 28, 2017 at 12:41
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The IP of the Linksys has not changed simply because it stopped servering DHCP requests for other PCs. If can still access it it the same IP it had before.

If you have forgotten which IP that was then first try the firat and last IPs of you network, since this is traditional the IP where a default gateway would be placed. And if I read your question correctly it was both DHCP server and default gateway before you made changes.

Example network:
192.168.1.0/24: → Expected IP: 192.168.1.1 or 192.168.1.254

If these are not correct then use a tool like nmap to scan all NICs on the network. If you are unluckly you will just get an list of all active devices on your subnet (3-4 IPs, try them all). If you are lucky if will even identify which one. Nmap is rather good at that but I never tried it on a tomato device.

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I am updating this old thread because my solution might fit your question the best. Using an app such as Fing (Android, iOS) will show you all of the devices that you can see on your network. I have a wireless router with dhcp disabled and had no problem finding the ip using the Fing app.

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This is not a pretty solution but this is how I did it tonight, with Linux.

1) Log into a Linux box
2) sudo the next step, or su
3) fire up wireshark
4) from the list of available capture interfaces select your ethernet card (for me eth0)
5) let it site for a bit, and collect some data
6) from the menu Statistics -> Conversation List -> IPv4
7) the window will fill up with all the IPs that have come across your interface card. (for me my network is 192.168.42.0 but the router/switch came up as 192.168.1.1)

The next steps are for if you find yourself where I was and the router/switch is on a different network then your real network

8) Since linux can have 2 IPs per network card, setup a second IP on the network that your router/switch is on.
  ex. ifconfig eth0:0 192.168.1.100 netmask 255.255.255.0 up
9) Log into your router/switch (hope you remember the username and password)
10) change the IP to one that you will remember.

Mind you do not do this on a network unless either you own it (your home network) or you have written permission to do it on their network.

0

You're still able to connect to the router that this is connected to, and serves as your DHCP, right? That might be able to have a list of connected devices. If not, you would at least know the base range of ip ranges (192.168.0.* or 192.168.1.*). If you know roughly how many other devices are connected, you could guess the address from there. Or reset that dhcp router, connect with some pc and find its ip address. Then connect the new dhcp-less router, and its ip will be +1 of the last known address.

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I faced this problem with DHCP recently. I searched the internet and could not find a step by step solution. So I had to contact an IT person. I made a tutorial which I am posting here for everyone. Here it is:

https://cupntea.wordpress.com/2015/05/13/how-to-access-your-router-when-dhcp-is-disabled-2/

I hope it helps as a general guide.

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  • 4
    Answers only referring to a link is generally discouraged due to its susceptibility to link rot. Please edit the linked information information into your answer.
    – Jarmund
    May 24, 2015 at 17:53
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becareful of setting DNS, it should set to your router ip address. for example, router dhcp is disable and router ip adress is 192.168.1.100, then in your computer ipv4 properties, dhcp is enable and dns must be set to 192.168.1.100. so that you can access router for changing setting.

I've tried that way and its working.

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  • I don't understand this, but regardless, it requires accessing the router, which the original poster can't do, so even if it makes sense, it doesn't seem to answer the question.
    – blm
    Jan 16, 2016 at 17:57

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