Skip to main content

networking - Changing routing on Mac with two Ethernet ports


I have a Mac tower which has two Ethernet ports. One is connected to our corporate network, the other to a non-corporate network. Priority order states that the non-corporate network comes first and thus all traffic is routed through that.


I'm looking to add a route so that anything on our corporate sub net is routed through en1 vs en0.



  • First, how do I find what the coporate subnet is?

  • Second, how do I add this properly as a route?

  • Third, I have MS communicator that I would like to route its traffic through en1 as well, how do I do that?



Answer



The answer to the first two questions should be ask your corporate IT person.


If you really need to do it yourself then open a command prompt and check the output of these commands:



  • ifconfig (shows the IP addresses you are using)

  • netstat -rn (shows the defined routes)


The third question is a bit harder. You wrote that Priority order states that the non-corporate network comes first. I assume this means the default gateway is set to the non-corporate network. If it was the other way around it would just have worked. Now you will have to find out what server(s) MS communicator tries to contact and add separate routes for that.



Edit:


This is how I understand your network.


Diagram with both networks and assumed default values Lets say the corp. network gets plugged into the NIC called en1.


Almost all larger networks use DHCP. This means your card will announce its presence on the red network (think it yelling 'Hi, I am here. Give me the information I need').


The DHCP server will respond and usually it will tell the the computer what it needs. Try this. I expect that you will get an IP number, netmask, a default gateway and the IP for the DNS servers.


The IP is what gets set on your NIC. Write this down because you might need it later. In this example I will assume you got 10.0.0.42


The netmask will tell you which part of 10.0.0.42 is your network, and which part is the identification for your computers. Combined these allow you to access the local corp. network.


If a computer is not on the local corp. network then your mac will send it to some computers who (hopefully) knows how to forward it. This is the default gateway. There is no guarantee that your corp. network uses one, but it is very likely and it is something we do not wish to use later on.



Now for the green ISP network.

I can be briefer because things are more or less the same. You are very likely to gets and IP, netmask, default gateway and DNS server IPs.


However you can only have one default gateway.


You wrote that you wanted to use the green network by default. So we will use the default gateway on this one.


This means that you can just connect the green network to en0 and let it auto configure, but that you want to manually configure the red network. This means that you will not be using DHCP on en1. Not using DHCP means you can create a conflict on that network (since we are no longer using the red DHCP server which is keeping IPs on the red network unique). So walk to corp. IT and ask for a fixed IP address. They will add that to the exclusion list on the DHCP server. I am going to assume you got 10.0.0.42 as IP number.


Now go to the Mac, boot with the green cable in en0, set for DHCP. You should be able to connect to the other green computers (test with ping) and to reach the internet.


Connect the red cable to en1. Do not set this on to DHCP. If you have a graphical network tool then enter these values: IP: 10.0.0.42 (the one given to you by IT), netmask 255.255.254.0 (also given to you by IT). You should now be able to connect the the corp. computers.


If you use a shell, use: - ifconfig en1 10.0.0.42 netmask 255.255.254.0 - /sbin/route add -net 10.0.0.0 -netmask 255.255.254.0 -interface en1


The first command should configure the interface on en1 so it can send and receive on the corp. network. The second command tell your mac that if it want to connect to a computer on the corp. network (as in, any computer whose IP starts with 10.0.0.x) then it should communicate via en1.



This should answer your question, though I have one more paragraph because I thing you will run into problems with DNS. The DNS services provided by the ISP/green network will translate computer names to IP numbers for computers on the internet. They are unlikely to know about computer names in the corp.network. You might need to:



  1. Either set DNS to use the ones from the red corp. network (and hope those also resolve hostnames on the internet)

  2. Specify one nameserver from green and one from red. (Which will likely cause a timeout when you try to resolve something)

  3. Or use a hosts file. There are several posts on that subject on superuser.


Comments

Post a Comment

Popular Posts

Use Google instead of Bing with Windows 10 search

I want to use Google Chrome and Google search instead of Bing when I search in Windows 10. Google Chrome is launched when I click on web, but it's Bing search. (My default search engine on Google and Edge is http://www.google.com ) I haven't found how to configure that. Someone can help me ? Answer There is no way to change the default in Cortana itself but you can redirect it in Chrome. You said that it opens the results in the Chrome browser but it used Bing search right? There's a Chrome extension now that will redirect Bing to Google, DuckDuckGo, or Yahoo , whichever you prefer. More information on that in the second link.
Post a Comment
Read more

linux - Using an index to make grep faster?

I find myself grepping the same codebase over and over. While it works great, each command takes about 10 seconds, so I am thinking about ways to make it faster. So can grep use some sort of index? I understand an index probably won't help for complicated regexps, but I use mostly very simple patters. Does an indexer exist for this case? EDIT: I know about ctags and the like, but I would like to do full-text search. Answer what about cscope , does this match your shoes? Allows searching code for: all references to a symbol global definitions functions called by a function functions calling a function text string regular expression pattern a file files including a file
Post a Comment
Read more

How do I transmit a single hexadecimal value serial data in PuTTY using an Alt code?

I am trying to sent a specific hexadecimal value across a serial COM port using PuTTY. Specifically, I want to send the hex codes 9C, B6, FC, and 8B. I have looked up the Alt codes for these and they are 156, 182, 252, and 139 respectively. However, whenever I input the Alt codes, a preceding hex value of C2 is sent before 9C, B6, and 8B so the values that are sent are C2 9C, C2 B6, and C2 8B. The value for FC is changed to C3 FC. Why are these values being placed before the hex value and why is FC being changed altogether? To me, it seems like there is a problem internally converting the Alt code to hex. Is there a way to directly input hex values without using Alt codes in PuTTY? Answer What you're seeing is just ordinary text character set conversion. As far as PuTTY is concerned, you are typing (and reading) text , not raw binary data, therefore it has to convert the text to bytes in whatever configured character set before sending it over the wire. In other words, when y
Post a Comment
Read more

networking - Windows 10, can ping other PC but cannot access shared folders! What gives?

I have a computer running Windows 7 that shares a Git repo on drive D. Let's call this PC " win7 ". This repo is the origin of a project that we push to and pull from. The network is a wireless network. One PC on this network is running on Windows 10. Let's call this PC " win10 ". Win10 can ping every other PC on the network including win7 . Win7 can ping win10 . Win7 can access all shared files on win10 . Neither of the PCs have passwords. Problem : Win10 cannot access any shared files on win7 , not from Explorer, nor from Git Bash or any other Git management system (E-Git on Eclipse or Visual Studio). So, win10 cannot pull/push. Every other PC on the network can access win7 shared files and push/pull to/from the shared Git origin. What's wrong with Windows 10? I have tried these: Control Panel\All Control Panel Items\Network and Sharing Center\Advanced sharing settings\ File sharing is on, Discovery is on, Password protected sharing is off Adapte
Post a Comment
Read more