static route randomly ignored

I have a couple of Linux guest VMs with bridged network to my physical adapter. For a certain reason I can't use the subnet of my host machine for the guests (and virtual adapter is too slow for me), so I created a separate subnet for them.

On host I added the guest subnet:

C:\> route add 192.168.20.0 mask 255.255.255.0 0.0.0.0 metric 1

On guests:

# route add -host 192.168.148.87 dev eth3 # my host ip

It mostly works:

basin@BASIN /cygdrive/c/Users/basin
$ tracert -d 192.168.20.20

Tracing route to 192.168.20.20 over a maximum of 30 hops

  1    <1 ms    <1 ms    <1 ms  192.168.20.20

Trace complete.

basin@BASIN /cygdrive/c/Users/basin
$ tracert -d 192.168.20.21

Tracing route to 192.168.20.21 over a maximum of 30 hops

  1    <1 ms    <1 ms    <1 ms  192.168.20.21

Trace complete.

But it looks like some packets go through the gateway:

basin@BASIN /cygdrive/c/Users/basin
$ tracert -d 192.168.20.23

Tracing route to 192.168.20.23 over a maximum of 30 hops

  2    <1 ms    <1 ms    <1 ms  192.168.200.1 0
  3  192.168.200.1  reports: Destination host unreachable.

Trace complete.

SSH connections to the guests often stall. What am I doing wrong?

IPv4 Route Table
===========================================================================
Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
          0.0.0.0          0.0.0.0  192.168.149.200   192.168.148.87     20
        127.0.0.0        255.0.0.0         On-link         127.0.0.1    306
        127.0.0.1  255.255.255.255         On-link         127.0.0.1    306
  127.255.255.255  255.255.255.255         On-link         127.0.0.1    306

     192.168.20.0    255.255.255.0         On-link    192.168.148.87     21
   192.168.20.255  255.255.255.255         On-link    192.168.148.87    276

     192.168.56.0    255.255.255.0         On-link      192.168.56.1    266
     192.168.56.1  255.255.255.255         On-link      192.168.56.1    266
   192.168.56.255  255.255.255.255         On-link      192.168.56.1    266

    192.168.148.0    255.255.254.0         On-link    192.168.148.87    276
   192.168.148.87  255.255.255.255         On-link    192.168.148.87    276

  192.168.149.255  255.255.255.255         On-link    192.168.148.87    276
        224.0.0.0        240.0.0.0         On-link         127.0.0.1    306
        224.0.0.0        240.0.0.0         On-link    192.168.148.87    276
        224.0.0.0        240.0.0.0         On-link      192.168.56.1    266
  255.255.255.255  255.255.255.255         On-link         127.0.0.1    306
  255.255.255.255  255.255.255.255         On-link    192.168.148.87    276
  255.255.255.255  255.255.255.255         On-link      192.168.56.1    266
===========================================================================

Upd:

Could it be that OS sends some ICMP request to different places and the reply overrides my static route? How to check this?

basin

Posted 2016-06-21T13:01:46.680

Reputation: 394

what virtualization solution are you using? I used VirtualBox on Windows (now I am on OS X and still using VirtualBox) and it has a nice Networking part which does not need additional setup on host/guest as you described. – Zina – 2016-06-21T22:26:49.130

@Zina I use VirtualBox. I explained my case in the 1st paragraph. Bridge gives me 2.5Gbit. Other modes - 100Mbit – basin – 2016-06-22T06:37:52.010

strange you cant get more than 100Mbit with other connections. What type of adapter did you select? A 1Gb or the PCnet? And I don't see where from the hop to 192.168.200.1 came? I do not see it in your routing table. – Zina – 2016-06-22T22:45:34.373

static route randomly ignored

Answers