Denys Vlasenko wrote:
Yes, it's normal.
Think about it. When you ping *yourself*,
do ping packets really go over the physical wire?
Of course not. They exist only inside your computer.
In other words, they go over _loopback interface_!
Proof:
# ip a
1: lo: <LOOPBACK,UP,10000> mtu 16436 qdisc noqueue
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,10000> mtu 1500 qdisc pfifo_fast qlen 1000
link/ether 00:1d:7d:c2:ec:70 brd ff:ff:ff:ff:ff:ff
inet 10.0.0.1/24 brd 10.0.0.255 scope global if
# ./busybox ping -I eth0 10.0.0.1
PING 10.0.0.1 (10.0.0.1): 56 data bytes
^C
--- 10.0.0.1 ping statistics ---
2 packets transmitted, 0 packets received, 100% packet loss
# ./busybox ping -I lo 10.0.0.1
PING 10.0.0.1 (10.0.0.1): 56 data bytes
64 bytes from 10.0.0.1: seq=0 ttl=64 time=0.089 ms
64 bytes from 10.0.0.1: seq=1 ttl=64 time=0.064 ms
64 bytes from 10.0.0.1: seq=2 ttl=64 time=0.065 ms
^C
--- 10.0.0.1 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max = 0.064/0.072/0.089 ms
--
vda
Hi Denis.
Makes sense what you say, i understand now.
One minor thing, though.
It seems that the "normal" ping from my PC (iputils-ping package -
Ubuntu Hardy) does show the echo replies, while busybox ping does not
show them:
My eth1 is 192.168.105.1
busybox.git$ sudo ./busybox -I eth1 192.168.105.1
PING 192.168.105.1 (192.168.105.1): 56 data bytes
--- 192.168.105.1 ping statistics ---
2 packets transmitted, 0 packets received, 100% packet loss
busybox.git$ ping -I eth1 192.168.105.1
PING 192.168.105.1 (192.168.105.1) from 192.168.105.1 eth1: 56(84) bytes
of data.
64 bytes from 192.168.105.1: icmp_seq=1 ttl=64 time=0.030 ms
64 bytes from 192.168.105.1: icmp_seq=2 ttl=64 time=0.024 ms
64 bytes from 192.168.105.1: icmp_seq=3 ttl=64 time=0.024 ms
--- 192.168.105.1 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 1998ms
The funny thing is that in both above cases (ping and busybox's ping) i
verified with wireshark that the ICMP frames where correctly send and
received (as you said through the lo interface).
No. Time Source Destination Protocol Info
1 0.000000 192.168.105.1 192.168.105.1 ICMP Echo
(ping) request
2 0.000025 192.168.105.1 192.168.105.1 ICMP Echo
(ping) reply
3 1.000088 192.168.105.1 192.168.105.1 ICMP Echo
(ping) request
4 1.000110 192.168.105.1 192.168.105.1 ICMP Echo
(ping) reply
5 2.000171 192.168.105.1 192.168.105.1 ICMP Echo
(ping) request
6 2.000194 192.168.105.1 192.168.105.1 ICMP Echo
(ping) reply
7 3.000259 192.168.105.1 192.168.105.1 ICMP Echo
(ping) request
8 3.000281 192.168.105.1 192.168.105.1 ICMP Echo
(ping) reply
9 4.000340 192.168.105.1 192.168.105.1 ICMP Echo
(ping) request
10 4.000363 192.168.105.1 192.168.105.1 ICMP Echo
(ping) reply
It is just busybox's ping not representing the replies while "normal"
ping does.
It's ok for me, i report this just in case it could be a bug.
--
Regards,
Javier Viguera
Software Engineer
http://www.digi.com
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