Static DHCP

[clarkkent333]

Hey guys, need a little prof assistance on this one. I'm trying to set up my WRT54G w/ DD-WRT to port forward and I'm attempting to assign it a static IP through Static DHCP. I setup the IP outside the default range of my router but it won't stick. When I check out the DHCP client table I see the original IP that my router assigned before I did this, and the new static IP. Problem is, I can't get the Static IP to take hold, and the router is running all my port forwarding through the original IP. Any suggestions on this?

I already tried running ipconfig /release and /renew and it still picked up the original IP. I also tried deleting it from the client table but that didn't work.

 

[nweaver]

depending on implementation...you can't assign a static address outside of your pool.

In MS stuff, you have your "Pool" (i.e 1-255") and your exclusions (don't give out 10, or 12) and your reservations (give xxxx.xxxx.xxxx this ip). The exclusions and reservations need to be in the range the pool is in.

 

[clarkkent333]

well I was going for .155 so that's <.255. I think I got it working by assigning it inside the TCP/IP properties of the network connection. I removed it from "Obtain IP Automatically" and punched in what I wanted. Is that the proper thing to do? Any drawbacks to that?

 

[Nothinman]

well I was going for .155 so that's <.255. I think I got it working by assigning it inside the TCP/IP properties of the network connection. I removed it from "Obtain IP Automatically" and punched in what I wanted. Is that the proper thing to do? Any drawbacks to that?

You're not using DHCP any more so if the info on the router changes (the only real thing there is probably DNS servers) that one client won't get the updated info, you'll have to enter it in manually. Also if the DHCP server on the router isn't smart it might hand out that address and cause a machine to dupe you.

 

[clarkkent333]

So is there a better way to do it?

BTW - this is my main router connected to my DSL modem. Don't know if that matters or not.

 

[Nothinman]

I always get frustrated when I'm forced to work with those crap SOHO routers with builtin DHCP and stuff, you'll have to figure what the thing wants you to do. At home I run my own DHCP server on a Linux box so I have a lot more control over how it works.

 

[JackMDS]

Actually some Entry Level Routers (The 802.11g line of Netgear and Buffalo Tech.), let you reserve an IP within the DHCP.

It means that you can leave the IP in the computer setting on Auto, and it would always obtain from the Router the same IP within the range of the DHCP pool.

:sun:

 

[nweaver]

You said you set it up "outside the range". AKA outside the pool. Change it to one int he pool

 

[clarkkent333]

Every tutorial on how to set it up says to pick up uptside the pool. I.E. if its assigning 100-150 then pick something below 100 or above 150.

 

[Nothinman]

Every tutorial on how to set it up says to pick up uptside the pool. I.E. if its assigning 100-150 then pick something below 100 or above 150.

That would only work if you're assigning a static address and don't want to use DHCP on that machine. If you want to use DHCP you can setup a reservation inside the range, this lets you use DHCP so you can centrally manage all of your network settings and you can still have machines get the same address every time.

 

[JW310]

Have you checked the instructions found here: http://wrt-wiki.bsr-clan.de/index.php?title=Static_DHCP ?

Double-check to make sure you have the MAC addresses set up correctly for the static DHCP settings on the router. And yes, you want to have the router assign the "static" addresses outside the range of the non-static DHCP IP addresses. So, for example, with the non-static DHCP range being .100-.150, you want to have the static DHCP config set to assign addresses outside that range, so below .100 or above .150

JW

 

[JW310]

Originally posted by: Nothinman

Every tutorial on how to set it up says to pick up uptside the pool. I.E. if its assigning 100-150 then pick something below 100 or above 150.

That would only work if you're assigning a static address and don't want to use DHCP on that machine. If you want to use DHCP you can setup a reservation inside the range, this lets you use DHCP so you can centrally manage all of your network settings and you can still have machines get the same address every time.

With the firmware he's using on his WRT54G, he shouldn't need to set the IP being assigned to that particular computer so that it's within the range of the DHCP server. I'm running a similar firmware on my WRT54G, with the default DHCP range (.100-.150), yet have my static DHCP addresses set up between .2 and .10, and it works fine.

JW

 

[xtknight]

I have my router (Cisco Linksys BEFSX41) set up to do DHCP on 192.168.1.100 to 192.168.1.109. I've statically set my IP to 192.168.1.101 (for DMZ) before just fine.

 

[Joemonkey]

here's a crazy question

why don't you assign a static IP on the box in question?

 

[JackMDS]

Originally posted by: Joemonkey
here's a crazy question

why don't you assign a static IP on the box in question?

Coz if the computer is a Laptop or a luggable that might be occasionally used in few Networks, it is more comfortable to keep the IP assignment on Auto.

:sun:

 

[Nothinman]

I'm running a similar firmware on my WRT54G, with the default DHCP range (.100-.150), yet have my static DHCP addresses set up between .2 and .10, and it works fine.

What do you mean by "works fine"? Do you mean that you plugged in all of the IP information statically and it works or it got the address between .2 and .10 and the rest of the IP information from the DHCP server? If it's the former that's f'd up, if it's the latter that defeats the purpose of using DHCP in the first place.

 

[JackMDS]

Assuming that you have 5 computers there IP is set to Auto.

Assuming that you have Entry Level Cable/DSL Router and the DHCP is set to ?Dish? IPs 192.168.1.10 to 192.168.115

There are few scenarios.

Most Routers will assign the 192.168.1.10 to the first computer that comes On and 192.168.1.11 to the second and so On.

If you switch Off every thing and start again the assignment will be again according to order to switch On the computers regardless of what happened before.

Some Router (as is) would keep (even if switched off) the computer?s MAC and might assign the same IP as before.

Some Routers (Buffalo 802.11g and few Netgear) have a special menu in which you can reserve IP according to the Computer?s MAC these reservation is part of the DHCP. I.e. the given IP has to be within the Range of the DHCP. Therefore, you can leave the computer?s IP setting on Auto and would pick up the same IP every time. Otherwise they assign the IPs as in case one (according to the ordr of switching On).

:sun:

 

[JW310]

Originally posted by: Nothinman

I'm running a similar firmware on my WRT54G, with the default DHCP range (.100-.150), yet have my static DHCP addresses set up between .2 and .10, and it works fine.

What do you mean by "works fine"? Do you mean that you plugged in all of the IP information statically and it works or it got the address between .2 and .10 and the rest of the IP information from the DHCP server? If it's the former that's f'd up, if it's the latter that defeats the purpose of using DHCP in the first place.

I mean it's set up as the latter - the router assigns all information, including the addresses between .2-.10, based on MAC address. JackMDS basically hit the nail on the head for why I have it set up that way:

Originally posted by: JackMDS
Coz if the computer is a Laptop or a luggable that might be occasionally used in few Networks, it is more comfortable to keep the IP assignment on Auto.

:sun:

 

[Nothinman]

I mean it's set up as the latter - the router assigns all information, including the addresses between .2-.10, based on MAC address. JackMDS basically hit the nail on the head for why I have it set up that way:

Then your router is retarded, it shouldn't be managing addresses outside of it's pool.

 

[JW310]

Originally posted by: Nothinman

I mean it's set up as the latter - the router assigns all information, including the addresses between .2-.10, based on MAC address. JackMDS basically hit the nail on the head for why I have it set up that way:

Then your router is retarded, it shouldn't be managing addresses outside of it's pool.

I've done the same thing using dhcpd in OpenBSD for a network that has ~15-20 computers that are almost always connected and any number that come & go (fraternity house network at a university that requires its students to own/lease a laptop).

Are you familiar with dhpcd, and its configuration file?

 

[Nothinman]

Yes, and all of my reservations are within the range dhcpd is told to manage.

 

[JW310]

Well then, apparently DHCPD is 'retarted' because the setup I'm using on the OpenBSD box works, even though the fixed-address lines I'm using are outside of the range defined in my dhcpd.conf file (shortened, obviously):

option domain-name "domain.name";
option domain-name-servers 192.168.0.1;
option netbios-name-servers 192.168.0.1;
option subnet-mask 255.255.255.0;

default-lease-time 3600;
max-lease-time 86400;
#ddns-update-style none;

subnet 192.168.0.0 netmask 255.255.255.0 {
range 192.168.0.180 192.168.0.249;
option routers 192.168.0.1;
}

# Brothers
group {
host xxxxxxx {
hardware ethernet 00:00:00:00:00:00;
fixed-address 192.168.0.2;
}
}

 

[Nothinman]

It's been a while since I read any docs on DHCP and I'm a little tuned up right now so I won't be looking it up, but even if it's the correct behavior it really seems dumb to mess with any addresses outside of the range the server is told to manage.

 

[blemoine]

if you are forwarding ports to a certain address and you want it to remain the same then set a static address. use dhcp for everyone else. or how bout this crazy idea. set everyone with a static ip address. unless you have a network with 50 + machines you can set static addresses. it has not been outlawed yet. but if you just have to have dhcp assigning addresses then get a dedicated server for it. this should basically solve your problems i would think. good luck though