netmask value for local ip

Post new topic   Reply to topic    DD-WRT Forum Index -> Atheros WiSOC based Hardware
Author Message
ai5g
DD-WRT Novice


Joined: 12 Dec 2016
Posts: 11

PostPosted: Fri Jun 18, 2021 12:17    Post subject: netmask value for local ip Reply with quote
I have just installed a recent version of dd-WRT on my R7800.
I now have trouble connecting via LAN to the router once I have adjusted the IP.

One change compared to my older Kong release is that I now must enter a netmask value for the "local IP". I don't get what this is good for. The router is supposed to have the IP 192.168.172.2, but I have to enter this netmask value. Apparently, the default is here 24, so it now says

Local IP 192.168.172.2/24

What does the /24 actually do here and what would be the correct value for me?
Sponsor
egc
DD-WRT Guru


Joined: 18 Mar 2014
Posts: 12837
Location: Netherlands

PostPosted: Fri Jun 18, 2021 12:32    Post subject: Reply with quote
The general questions forum is not for asking for help.

See the first thread.

To get the best out of DDWRT and the forum read the forum guidelines with helpful pointers:
https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=324087

If you have not already read the forum guidelines, please do !!

A recent version can mean a lot, it helps if you are more specific e.g. always state router model and build number

255.255.255.0 is equivalent to /24 which is a class C subnet which is normally used.

/24 is CIDR notation.

I will transfer this to the right forum Smile

_________________
Routers:Netgear R7000, R6400v1, R6400v2, EA6900 (XvortexCFE), E2000, E1200v1, WRT54GS v1.
Install guide R6400v2, R6700v3,XR300:https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=316399
Install guide R7800/XR500: https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=320614
Forum Guide Lines (important read):https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=324087
ai5g
DD-WRT Novice


Joined: 12 Dec 2016
Posts: 11

PostPosted: Fri Jun 18, 2021 12:46    Post subject: Reply with quote
Thank you for the answer and sorry for posting in the wrong forum.

SO I understand that /24 would be the right choice for me?
lexridge
DD-WRT Guru


Joined: 07 Jun 2006
Posts: 964
Location: WV, USA

PostPosted: Fri Jun 18, 2021 12:51    Post subject: Reply with quote
ai5g wrote:
Thank you for the answer and sorry for posting in the wrong forum.

SO I understand that /24 would be the right choice for me?


Correct. /24 would be correct for probably 98% of all users. That gives you an IP range of 192.168.172.1 - 192.168.172.254.

_________________
Linksys EA8500 (Internet Gateway, AP/VAP) - DD-WRT r53562
Features in use: WDS-AP, Multiple VLANs, Samba, WireGuard, Entware: mqtt, mlocate

Netgear R7800 (WDS-AP, WAP, VAP) - DD-WRT r53562
Features in use: multiple VLANs over single trunk port

Linksys EA8500 WDS Station x2 - DD-WRT r53562

Netgear R6400v2 WAP, VAP 2.4ghz only w/VLANs over single trunk port.

OSes: Fedora 38, 9 RPis (2,3,4,5), 20 ESP8266s: Straight from Amiga to Linux in '94, never having owned a Windows PC.

Forum member #248
ai5g
DD-WRT Novice


Joined: 12 Dec 2016
Posts: 11

PostPosted: Fri Jun 18, 2021 13:08    Post subject: Reply with quote
I am still not getting this. Maybe a bit more detailed:

I have a cable modem+router in the basement (192.168.172.1), which is also steup as a DHCP-Server for my network. The R7800 should basically serve as a wireless AP and eventually also provide VPN service. Thus, the R7800 should have the IP 192.168.178.2 and should be set to "DHCP Forwarder", to forward the IPs generated by the router in the basement.

When I only need a specific single IP address for the router, why would I need a netmask? What would the generated range be good for?

Seems that I have a significant knwoledge gap here. Sorry if this is too basic ;-(
egc
DD-WRT Guru


Joined: 18 Mar 2014
Posts: 12837
Location: Netherlands

PostPosted: Fri Jun 18, 2021 15:31    Post subject: Reply with quote
DHCP should be off and not set as forwarder

It is OK if you do not understand everything (I do not understand everything either) that is what the wiki is for, just follow the instructions:
https://wiki.dd-wrt.com/wiki/index.php/Wireless_Access_Point

and 255.255.255.0 is /24 google CIDR notation

_________________
Routers:Netgear R7000, R6400v1, R6400v2, EA6900 (XvortexCFE), E2000, E1200v1, WRT54GS v1.
Install guide R6400v2, R6700v3,XR300:https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=316399
Install guide R7800/XR500: https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=320614
Forum Guide Lines (important read):https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=324087
lexridge
DD-WRT Guru


Joined: 07 Jun 2006
Posts: 964
Location: WV, USA

PostPosted: Fri Jun 18, 2021 15:57    Post subject: Reply with quote
For a better understanding of netmasks, I found it helpful to try different things using a netmask calculator.
https://www.calculator.net/ip-subnet-calculator.html

_________________
Linksys EA8500 (Internet Gateway, AP/VAP) - DD-WRT r53562
Features in use: WDS-AP, Multiple VLANs, Samba, WireGuard, Entware: mqtt, mlocate

Netgear R7800 (WDS-AP, WAP, VAP) - DD-WRT r53562
Features in use: multiple VLANs over single trunk port

Linksys EA8500 WDS Station x2 - DD-WRT r53562

Netgear R6400v2 WAP, VAP 2.4ghz only w/VLANs over single trunk port.

OSes: Fedora 38, 9 RPis (2,3,4,5), 20 ESP8266s: Straight from Amiga to Linux in '94, never having owned a Windows PC.

Forum member #248
Per Yngve Berg
DD-WRT Guru


Joined: 13 Aug 2013
Posts: 6858
Location: Romerike, Norway

PostPosted: Fri Jun 18, 2021 16:12    Post subject: Reply with quote
Every IP needs a netmask. That's how it's determined if the other address that you communicate with is on the same sub-net or not.

If same network, the packet is sent directly.
If other, the packet is sent to the router.
lexridge
DD-WRT Guru


Joined: 07 Jun 2006
Posts: 964
Location: WV, USA

PostPosted: Fri Jun 18, 2021 16:13    Post subject: Reply with quote
ai5g wrote:
I am still not getting this. Maybe a bit more detailed:

I have a cable modem+router in the basement (192.168.172.1), which is also steup as a DHCP-Server for my network. The R7800 should basically serve as a wireless AP and eventually also provide VPN service. Thus, the R7800 should have the IP 192.168.178.2 and should be set to "DHCP Forwarder", to forward the IPs generated by the router in the basement.

When I only need a specific single IP address for the router, why would I need a netmask? What would the generated range be good for?

Seems that I have a significant knwoledge gap here. Sorry if this is too basic ;-(


First, you need to connect the modem+router to one of the R7800 LAN ports, not the WAN port. You may disable the WAN port, for that matter. The netmask is necessary to the R7800 to understand what IP addresses, known as a subnet, that it may communicate with. The netmask defines this, whether it is in CIDR /24 notation or the 255.255.255.0 notation.

This netmask gives your network 253 usable addresses. 192.168.172.0 is your network address, and 192.168.172.255 is your broadcast address, neither of these are usable.

_________________
Linksys EA8500 (Internet Gateway, AP/VAP) - DD-WRT r53562
Features in use: WDS-AP, Multiple VLANs, Samba, WireGuard, Entware: mqtt, mlocate

Netgear R7800 (WDS-AP, WAP, VAP) - DD-WRT r53562
Features in use: multiple VLANs over single trunk port

Linksys EA8500 WDS Station x2 - DD-WRT r53562

Netgear R6400v2 WAP, VAP 2.4ghz only w/VLANs over single trunk port.

OSes: Fedora 38, 9 RPis (2,3,4,5), 20 ESP8266s: Straight from Amiga to Linux in '94, never having owned a Windows PC.

Forum member #248
Per Yngve Berg
DD-WRT Guru


Joined: 13 Aug 2013
Posts: 6858
Location: Romerike, Norway

PostPosted: Fri Jun 18, 2021 16:29    Post subject: Reply with quote
192.168.172.1 must also be filled in in the Gateway field.
Display posts from previous:    Page 1 of 1
Post new topic   Reply to topic    DD-WRT Forum Index -> Atheros WiSOC based Hardware All times are GMT

Navigation

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You cannot download files in this forum