Mac OS ignores DHCP routes

blinkfrog · May 15, 2009

I'm a switcher. Just have buyed a mac.

My network provider is giving following connection settings: "Get IP address automatically; Get DNS server address autimatically" for network connection and some pppoe settings for internet.

On my windoze computer all network resources are accessible. But on my mac only internet is working and local resources like ftp-server, forum etc. are unavailable.

After some research I noticed that Mac OS ignores routing information providing by DHCP. I tried "sudo route add -net 192.168.0.0 -netmask 255.255.0.0 192.168.130.254" command and ftp and forum are available now.

But in windoze all network things are accesible just "out of the box". Is there any way to force Mac OS use DHCP routes and be "just works"?

richard.mac · May 15, 2009

blinkfrog said:
"Get IP address automatically; Get DNS server address autimatically" for network connection and some pppoe settings for internet.

you can add PPPoE in Network preferences for Ethernet in the configure menu.

blinkfrog · May 15, 2009

richthomas said:
you can add PPPoE in Network preferences for Ethernet in the configure menu.

It is added already and in my network it is used only for internet connection.
And in my network it isn't required to add pppoe to access local resources. Local resources are accessible throught dhcp routes.

lostngone · May 15, 2009

DHCP doesn't usually add any route other then your default gateway.

Most likely your provider only allows 1 PPPoe connection. If your PC is connected already then your mac won't be able to unless you route everything though the PC. A router would be a lot better choice.

Edit: Where are these "local resources" located on your network? Are they on the same subnet as the Mac? How is your network setup?

blinkfrog · May 15, 2009

I am sorry, it is likely my English too bad (I'm not native speaker).
I'm not need to connect both my pc and mac.
Problem is Mac OS ignores static routes provided by DHCP and I need to type it manually (or by script). These routes are used for local network resources access. And I am wondering if Mac OS can get these routes from dhcp automatically like windows do.

lostngone · May 15, 2009

blinkfrog said:
I am sorry, it is likely my English too bad (I'm not native speaker).
I'm not need to connect both my pc and mac.
Problem is Mac OS ignores static routes provided by DHCP and I need to type it manually (or by script). These routes are using for local network resources access. And I am wondering if Mac OS can get these routes from dhcp automatically like windows do.

You normally get 1 route from a DHCP host. This is your Default Gateway or Router address. Everything that is not on the same subnet as your Mac will get sent to that IP and routed to the Internet.

What is "192.168.130.254" Is that the Default Gateway that your ISP normally assigns to its hosts?

How is your network setup? Do you just have a DSL modem and a switch with both the Mac and PC plugged into it?

blinkfrog · May 15, 2009

lostngone said:
You normally get 1 route from a DHCP host. This is your Default Gateway or Router address. Everything that is not on the same subnet as your Mac will get sent to that IP and routed to the Internet.

Yes. And there is other subnets consisting local resources. DHCP server send routes to these subnets and Windows get it and use it. Mac OS don't.

lostngone said:
What is "192.168.130.254" Is that the Default Gateway that your ISP normally assigns to its hosts?
How is your network setup? Do you just have a DSL modem and a switch with both the Mac and PC plugged into it?

192.168.130.254 is DHCP server.
Main local resources are placed in subnet 192.168.128.*
I haven't any modem or router. Just ethernet cable coming to my home. I can plug it either to pc or to mac at the same time.
IP address and DNS server info is receiving from DHCP automatically.
When the cable is plugged then local resources are accessible (using routing information provided by dhcp in windows. In Mac OS I need to write "sudo route add...").
If I need internet I have to rise pppoe interface.

I realize that the best way is to purchase good router. Or I can write a script. But I want to know just on principle if Mac OS can use routing information received from DHCP server like windows can.

lostngone · May 15, 2009

I guess I am not getting it.

Maybe someone else can jump in, sorry for sounding stupid.

blinkfrog · May 17, 2009

It seems Mac OS ignores both dhcp options classless-routes code 121 and windows-routes code 249.

beckit · Oct 8, 2016

blinkfrog said:
It seems Mac OS ignores both dhcp options classless-routes code 121 and windows-routes code 249.

Hello 2009! In 2015 El Capitan brings in RFC 3442 (DHCP Option 121, etc.) support.

For older versions of macOS, I wrote DHCP option 121 handling software. Its a complete package that requires no forced configurations on the server (outside of an option 121 in the first place, of course)

I've an answer to a similar topic posted on Stackexchange as http://serverfault.com/a/807927/379808 and the software is available here: https://github.com/beckit/DHCP_121_macOS

TatoMCSE · Jul 26, 2018

beckit said:
Hello 2009! In 2015 El Capitan brings in RFC 3442 (DHCP Option 121, etc.) support.

For older versions of macOS, I wrote DHCP option 121 handling software. Its a complete package that requires no forced configurations on the server (outside of an option 121 in the first place, of course)

I've an answer to a similar topic posted on Stackexchange as http://serverfault.com/a/807927/379808 and the software is available here: https://github.com/beckit/DHCP_121_macOS

Hello 2009 and 2015. How is that possible that using the latest and greatest macOS I still don't get Option 121 working. I need to either add routes manually or mess up with ICMP redirects - which in turn need to be allowed via sudo sysctl net.inet.icmp.drop_redirect=0

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