How to reload default Mac OSX routing table without rebooting
Greetings,
I'm using vpnc for a VPN client. I'm also doing some tricky things with route to make sure I can still access my local network, etc. etc. (the particulars here are not very important).
Sometimes I get the routing table so jacked up I get ping: sendto: Network is unreachable for urls that should otherwise resolve.
Currently, if I restart Mac OS X then everything is back to normal. What I'd like to do is reset the routing tables to the "default" (e.g. what it is set to at boot) without a whole system reboot.
I think that step 1 is route flush (to remove all routes). And step 2 needs to reload all of the default routes.
Any thoughts on how to do this? (e.g. what is step 2?)
EDIT
Also, I'm noticing another symptom is traceroute also fails on the address in question. For instance:
traceroute the.good.dns.name
traceroute: bind: Can't assign requested address
You need to flush the routes . Use route -n flush several times . Afterwards add your routes with route add.
I was running into this issue while using a home OpenVPN server and connecting to it using the Tunnelblick application on Mac.
What was happening on my end is that a route with my home IP as the destination and an incorrect gateway was getting leftover after disconnecting from the VPN. Deleting this route solved the issue, simply
$ sudo route -n delete the.good.dns.name
Example: I am at school and after a fresh computer boot, I connect to a wireless network. I connect to my home OpenVPN server with Tunnelblick.
$ netstat -nr
Destination Gateway
....
[home-ip]/32 [school-default-gateway-1] ....
....
I disconnect from the VPN server. I change wireless networks. This changes my default gateway.
$ netstat -nr
Destination Gateway
...
[home-ip]/32 [school-default-gateway-1] ...
...
$ ping [home-ip]
PING [home-ip]: 56 data bytes
ping: sendto: Network is unreachable
ping: sendto: Network is unreachable
Request timeout for icmp_seq 0
...
I can't under any circumstances connect to my home network (VPN, ping, anything) after this happens. If I then just delete the route:
$ sudo route -n delete [home-ip]
delete net [home-ip]
$ ping [home-ip]
PING [home-ip]: 56 data bytes
64 bytes from [home-ip]: icmp_seq=1 ttl=56 time=13.111 ms
It works fine.
There might be an issue with how the OpenVPN server/client is configured which is leaving this (and I'd be interested in finding out what that is), but I installed a Tunnelblick post-disconnect script that automates this route deletion.
First you need a route for your network interface. If the VPN is disconnected then just take your network interface down and then bring it back up with ifconfig. Then use the route commnand to build in your default gw. So something like:
ifconfig en0 down
ifconfig en0 up
route add <ip address> default
I was running into the same issue as @Sean (I'm also running OS X), in that when I switched between home and work networks the default route was not getting deleted.
For completeness, when I connect to my VPN at home and running the following command, it'd show the default gateway as below
$ netstat -nr
Destination Gateway
...
[home-ip]/32 [work-default-gateway-1]
And when I disconnected, the [home-ip] gateway would still be there. When I'd connect to my work network I couldn't connect to the internet at all, and run into the same issue as OP
$ traceroute the.good.dns.name
$ traceroute: bind: Can't assign requested address
I'd then have to manually delete the route with
$ sudo route -n delete [home-ip]
Initially I put the "route -n delete" in a post-disconnect.sh script, but that was a little messy so instead I found this link
https://code.google.com/p/tunnelblick/issues/detail?id=177
Apparently the reason is due to setting the following in my .ovpn file
user nobody
group nogroup
Which means the route is set up as root, but when the connection is taken down the user is no longer root, so the route can't be deleted.
Commenting these 2 lines in my .ovpn file fixed the problem, without having to use a post-disconnect.sh.