Understanding routing table in a jail

M

Michael-O

Folks,

I just started using jails via ezjail(8). After having created the very first jail (resolv.conf copied from host) with a local and internal IP address I do not understand the routing table.

On the host I have:

rc.conf:

Code: 
# Network
ifconfig_bge0="inet 147.54.64.17  netmask 255.255.252.0"
defaultrouter="147.54.64.1"

# Jail Configs
cloned_interfaces="lo1"
ifconfig_lo1_aliases="inet 127.0.1.1-7/29"
ezjail_enable="YES"

Created the jail:
Code: 
ezjail-admin create deblndw011x1j.ad001.siemens.net 'lo1|127.0.1.2,bge0|147.54.64.55'

This is ifconfig after the jail has been started:

Code: 
2488 # ifconfig
bge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=c019b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4,VLAN_HWTSO,LINKSTATE>
        ether 20:67:7c:d4:58:40
        inet 147.54.64.17 netmask 0xfffffc00 broadcast 147.54.67.255
        inet 147.54.64.55 netmask 0xffffffff broadcast 147.54.64.55
        media: Ethernet autoselect (1000baseT <full-duplex>)
        status: active
        nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
        options=680003<RXCSUM,TXCSUM,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
        inet6 ::1 prefixlen 128
        inet6 fe80::1%lo0 prefixlen 64 scopeid 0x5
        inet 127.0.0.1 netmask 0xff000000
        groups: lo
        nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
lo1: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
        options=680003<RXCSUM,TXCSUM,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
        inet 127.0.1.1 netmask 0xfffffff8
        inet 127.0.1.3 netmask 0xffffffff
        inet 127.0.1.4 netmask 0xffffffff
        inet 127.0.1.5 netmask 0xffffffff
        inet 127.0.1.6 netmask 0xffffffff
        inet 127.0.1.7 netmask 0xffffffff
        inet 127.0.1.2 netmask 0xffffffff
        groups: lo
        nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>

and its routing table:
Code: 
Routing tables

Internet:
Destination        Gateway            Flags     Netif Expire
default            147.54.64.1        UGS        bge0
127.0.0.1          link#5             UH          lo0
127.0.1.1          link#6             UH          lo1
127.0.1.2          link#6             UH          lo1
127.0.1.3          link#6             UH          lo1
127.0.1.4          link#6             UH          lo1
127.0.1.5          link#6             UH          lo1
127.0.1.6          link#6             UH          lo1
127.0.1.7          link#6             UH          lo1
147.54.64.0/22     link#1             U          bge0
147.54.64.17       link#1             UHS         lo0
147.54.64.55       link#1             UHS         lo0
147.54.64.55/32    link#1             U          bge0

new the jail:

Code: 
bge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=c019b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4,VLAN_HWTSO,LINKSTATE>
        ether 20:67:7c:d4:58:40
        inet 147.54.64.55 netmask 0xffffffff broadcast 147.54.64.55
        media: Ethernet autoselect (1000baseT <full-duplex>)
        status: active
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
        options=680003<RXCSUM,TXCSUM,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
        groups: lo
lo1: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
        options=680003<RXCSUM,TXCSUM,LINKSTATE,RXCSUM_IPV6,TXCSUM_IPV6>
        inet 127.0.1.2 netmask 0xffffffff
        groups: lo

and the jail's routing table:
Code: 
Routing tables

Internet:
Destination        Gateway            Flags     Netif Expire
127.0.1.2          link#6             UH          lo1
147.54.64.55       link#1             UHS         lo0

My questions now are:
  • Why is there lo0 on the jail when I have assigned lo1 as the first interface?
  • Why is the jail's routing table so empty, why is bge0 not listed and no default gateway?
  • Is the jail usable with this network configuration?
DNS resolution works, fetch works too.

Thanks a lot!
 
A standard jail does not have an "own" routing table. Instead, networking and routes are handled by the host. Think of jail networking more as of a "filtered/masked view" on host interfaces and IPs.

If you require a full network stack inside a jail, including dedicated routing table, have a look at vnet(9).

Regards
 
Alright, this makes sense. This is actually what I have assumed.
I don't need another network stack for the jail. I am happy how it works right now.

Thank you!
 
You must log in or register to reply here.
Back
Top