Em 16-11-2011 17:48, Dale Dellutri escreveu:
> I have an ethernet device in my lan with a primary address 192.168.5.205
> and a secondary address .217. I added the secondary address after network
> startup established the primary address by an ip addr add command:
>
> # ip addr add 192.168.5.217/24 broadcast 192.168.5.255 dev eth0
>
> # ip addr show
> ...
> 2: eth0:<BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
> link/ether 78:2b:cb:23:21:4c brd ff:ff:ff:ff:ff:ff
> inet 192.168.5.205/24 brd 192.168.5.255 scope global eth0
> inet 192.168.5.217/24 brd 192.168.5.255 scope global secondary eth0
> inet6 fe80::7a2b:cbff:fe23:214c/64 scope link
> valid_lft forever preferred_lft forever
> ...
>
> Then I add a new route via a network gateway but I want the route to use
> the secondary address as a source.
>
> # ip route add 11.11.11.11 via 192.168.5.148 src 192.168.5.217
>
> And the ip route show command shows that it knows the source.
>
> # ip route show
> 11.11.11.11 via 192.168.5.148 dev eth0 src 192.168.5.217
>
> But where is the source address kept? If I look at /proc/net/route,
> it shows the route (0B0B0B0B = 11.11.11.11), but not the source
> address.
>
> # cat /proc/net/route
> Iface Destination Gateway Flags RefCnt Use Metric Mask MTU Window IRTT
> eth0 0B0B0B0B 9405A8C0 0007 0 0 0 FFFFFFFF 0 0 0
> ...
>
> Where is the source address kept?
>
ip route uses NETLINK to obtain info
I did:
strace -o /tmp/strace.out ip route show
and inside strace.out:
bind(3, {sa_family=AF_NETLINK, pid=0, groups=00000000}, 12) = 0
sendto(3, "\24\0\0\0\22\0\1\0031\25\304N\0\0\0\0\0\0\0\0", 20, 0,
{sa_family=AF_NETLINK, pid=0, groups=00000000}, 12) = 20
recvmsg(3, {msg_name(12)={sa_family=AF_NETLINK, pid=0, groups=00000000},
msg_iov(1)=[{"\364\0\0\0\20\0\2\0001\25\304N\"\r\0\0\0\0\4\3\1\0\0\0I\0\1\0\0\0\0\0"...,
16384}], msg_controllen=0, msg_flags=0}, 0) = 1688
You can see /proc/net/rt_cache, there is a Source column there.
--
Marcelo Beckmann
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