Macos – How to direct IP route through specific interface in OS X

macosrouting

I'm on a mac and trying to route a particular address though a specific gateway on my wifi connection.

I'm using:

route add -host 54.81.143.201 192.168.15.1

Sometimes this will work, other times it wont. What I found is that the interface it chooses is different every time. It needs ot be en0 to work

netstat -nr output when it doesn't work:

54.81.143.201      192.168.15.1       UGHS            1       89     en5

This is when it does work: (note en0)

54.81.143.201      192.168.15.1       UGHS            0        1     en

Why am I doing this? Because our company has a proxy that HipChat doesn't work on. So I'm routing hipchat traffic through an open wifi network while still being on my works ethernet.

EDIT:

I also tried adding the entry using just the interface

route add -host 54.81.143.201 -interface en0

54.81.143.201      78:31:c1:c7:52:74  UHS             0        2     en0

HipChat fails to connect.

EDIT 2:
Someone asked for my whole routing table, here it is today. Note that 54.81.143.201 is now bound to en3 and not en0

Internet:
Destination        Gateway            Flags        Refs      Use   Netif Expire
default            10.7.90.1          UGSc           31        6     en3
10.7.90/24         link#4             UCS             4        0     en3
10.7.90.1          0:23:ac:3d:db:c2   UHLWIir        16        0     en3   1200
10.7.90.44         40:6c:8f:19:4a:bb  UHLWI           0        3     en3    946
10.7.90.63         127.0.0.1          UHS             0        0     lo0
54.81.143.201      192.168.15.1       UGHS            0        0     en3
127                127.0.0.1          UCS             0        0     lo0
127.0.0.1          127.0.0.1          UH              3      209     lo0
169.254            link#4             UCS             1        0     en3
169.254.255.255    0:23:ac:3d:db:c2   UHLSW           0        0     en3

Best Answer

Try:

route add -host 54.81.143.201 -interface en0

Related Solutions

Ubuntu – How to route the incoming connections through a specific interface

I found the solution for this myself: Routing for multiple uplinks/providers

A common configuration is the following, in which there are two providers that connect a local network (or even a single machine) to the big Internet.

                                                               ________
                                          +------------+        /
                                          |            |       |
                            +-------------+ Provider 1 +-------
        __                  |             |            |     /
    ___/  \_         +------+-------+     +------------+    |
  _/        \__      |     if1      |                      /
 /             \     |              |                      |
| Local network -----+ Linux router |                      |     Internet
 \_           __/    |              |                      |
   \__     __/       |     if2      |                      \
      \___/          +------+-------+     +------------+    |
                            |             |            |     \
                            +-------------+ Provider 2 +-------
                                          |            |       |
                                          +------------+        \________

how to route answers to packets coming in over a particular provider, say Provider 1, back out again over that same provider.

Let us first set some symbolical names. Let $IF1 be the name of the first interface (if1 in the picture above) and $IF2 the name of the second interface. Then let $IP1 be the IP address associated with $IF1 and $IP2 the IP address associated with $IF2. Next, let $P1 be the IP address of the gateway at Provider 1, and $P2 the IP address of the gateway at provider 2. Finally, let $P1_NET be the IP network $P1 is in, and $P2_NET the IP network $P2 is in.

One creates two additional routing tables, say T1 and T2. These are added in /etc/iproute2/rt_tables. Then you set up routing in these tables as follows:

  ip route add $P1_NET dev $IF1 src $IP1 table T1
  ip route add default via $P1 table T1
  ip route add $P2_NET dev $IF2 src $IP2 table T2
  ip route add default via $P2 table T2

Nothing spectacular, just build a route to the gateway and build a default route via that gateway, as you would do in the case of a single upstream provider, but put the routes in a separate table per provider. Note that the network route suffices, as it tells you how to find any host in that network, which includes the gateway, as specified above. Next you set up the main routing table. It is a good idea to route things to the direct neighbour through the interface connected to that neighbour. Note the `src' arguments, they make sure the right outgoing IP address is chosen.

    ip route add $P1_NET dev $IF1 src $IP1
    ip route add $P2_NET dev $IF2 src $IP2

Then, your preference for default route: ip route add default via $P1

Next, you set up the routing rules. These actually choose what routing table to route with. You want to make sure that you route out a given interface if you already have the corresponding source address: ip rule add from $IP1 table T1 ip rule add from $IP2 table T2

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