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pacmac
Tux's lil' helper
Tux's lil' helper


Joined: 25 Apr 2003
Posts: 83

PostPosted: Sun May 01, 2016 1:30 pm    Post subject: Networking problem [SOLVED] Reply with quote

Hello,

I have two machines in my network.

router panel info:

Code:
8c89a59ac478   192.168.000.014   255.255.255.000   D:-- H:-- M:-- S:--   *** STATIC IP ADDRESS **   
c8bcc8a5194b   192.168.000.015   255.255.255.000   D:-- H:-- M:-- S:--   *** STATIC IP ADDRESS **   


iMac machine ifconfig:

Code:
en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
   options=b<RXCSUM,TXCSUM,VLAN_HWTAGGING>
   ether c8:bc:c8:a5:19:4b
   inet6 fe80::cabc:c8ff:fea5:194b%en0 prefixlen 64 scopeid 0x4
   inet 192.168.0.15 netmask 0xffffff00 broadcast 192.168.0.255
   nd6 options=1<PERFORMNUD>
   media: autoselect (1000baseT <full-duplex,flow-control>)
   status: active


Gentoo box ifconfig:

Code:
enp3s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.0.14  netmask 255.255.255.255  broadcast 192.168.0.14
        inet6 fe80::8e89:a5ff:fe9a:c478  prefixlen 64  scopeid 0x20<link>
        ether 8c:89:a5:9a:c4:78  txqueuelen 1000  (Ethernet)
        RX packets 157665210  bytes 234227239891 (218.1 GiB)
        RX errors 2  dropped 697  overruns 0  frame 2
        TX packets 84235514  bytes 5966811707 (5.5 GiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0


ping from iMac (192.168.0.15) to Gentoo:

Code:
$ ping 192.168.0.14
PING 192.168.0.14 (192.168.0.14): 56 data bytes
Request timeout for icmp_seq 0
Request timeout for icmp_seq 1
Request timeout for icmp_seq 2
Request timeout for icmp_seq 3
Request timeout for icmp_seq 4
ping: sendto: No route to host
Request timeout for icmp_seq 5
ping: sendto: Host is down


ping from Gentoo (192.168.0.14) to iMac:

Code:
# ping 192.168.0.15
PING 192.168.0.15 (192.168.0.15) 56(84) bytes of data.
64 bytes from 192.168.0.15: icmp_seq=1 ttl=64 time=0.032 ms
64 bytes from 192.168.0.15: icmp_seq=2 ttl=64 time=0.031 ms
64 bytes from 192.168.0.15: icmp_seq=3 ttl=64 time=0.030 ms
64 bytes from 192.168.0.15: icmp_seq=4 ttl=64 time=0.032 ms



both will ping the router and to the internet. Sometimes, I don't know why, iMac can't ping to the router and can't access to it's panel but have internet connection, another times iMac has the error: IP already in use (I have tried several router ethernet connections and other IPs that I'm sure that they are free and always the same when this error occurs).

Gentoo box is connected to the router through a pair of PLC's:

http://www.amazon.com/TP-LINK-TL-PA4010P-AV500-Powerline-Through/dp/B00BUL8762/ref=sr_1_1?ie=UTF8&qid=1462109117&sr=8-1&keywords=TP-LINK+TL-PA4010P+KIT

My router is a CableModem Thomson TWG870

in the moment of collecting this information, I was mispelled config and iMac ip was 192.168.0.16, but there was no other machine at 192.168.0.15 and it was responding (the 192.168.0.15) to the ping from Gentoo, I have tried to change iMac ip to other (192.168.0.15 and then others) and the IP address already in use occured.

EDIT: Every IP that I ping from the Gentoo box responds to the pings lol What's the problem here? The PLC or the cablemodem?


Last edited by pacmac on Sun May 01, 2016 2:04 pm; edited 2 times in total
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NeddySeagoon
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Joined: 05 Jul 2003
Posts: 42559
Location: 56N 3W

PostPosted: Sun May 01, 2016 1:44 pm    Post subject: Reply with quote

pacmac,

Something is not self consistent here.

Code:
c8bcc8a5194b   192.168.000.016   255.255.255.000   D:-- H:-- M:-- S:--   *** STATIC IP ADDRESS **

is your iMac. The c8bcc8a5194b is the MACAddress, with the colons missing.
en0::
   ether c8:bc:c8:a5:19:4b
   inet 192.168.0.15 netmask 0xffffff00 broadcast 192.168.0.255


Which IP is the iMac really on?

Have you allocated static IP addresses inside the range that the router will allocate for dhcp?
That can lead to IP address collisions.

If you want dhcp and static in the same pange, you can tell dhcp to allocate a fixed IP by Mac Addr.

You may want to play with wireshark or tcpdump to see where the traffic is going.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.
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pacmac
Tux's lil' helper
Tux's lil' helper


Joined: 25 Apr 2003
Posts: 83

PostPosted: Sun May 01, 2016 1:47 pm    Post subject: Reply with quote

NeddySeagoon wrote:
pacmac,

Something is not self consistent here.

Code:
c8bcc8a5194b   192.168.000.016   255.255.255.000   D:-- H:-- M:-- S:--   *** STATIC IP ADDRESS **

is your iMac. The c8bcc8a5194b is the MACAddress, with the colons missing.
en0::
   ether c8:bc:c8:a5:19:4b
   inet 192.168.0.15 netmask 0xffffff00 broadcast 192.168.0.255


Which IP is the iMac really on?

Have you allocated static IP addresses inside the range that the router will allocate for dhcp?
That can lead to IP address collisions.

If you want dhcp and static in the same pange, you can tell dhcp to allocate a fixed IP by Mac Addr.

You may want to play with wireshark or tcpdump to see where the traffic is going.


Please, forget that thing, It's the paste from when the iMac was at 102.168.0.16. I repeated all the tests with iMac at 192.168.0.15 with same results. Sorry about the noob error. I have edited the OP to correct this error.

Could there any problem with the Gentoo box broadcast at 192.168.0.14 ?

The router DHCP range are from 192.168.0.10 to 192.168.0.254

EDIT: I have changed the DHCP range in the router config as you told me. I have set it up from 192.168.0.40 to 192.168.0.254. also I have added the line "static broadcast_address 192.168.0.255" to /etc/dhcpcd.conf and now I doesn't have this problem. I can ping both hosts and I can access through ftp to the iMac machine (I couldn't before), and there is no response to pings to IP's that are not assigned to any machine, so I think that the problem is solved. I'll put (solved) in the topic for the moment. THANK YOU.
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NeddySeagoon
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Joined: 05 Jul 2003
Posts: 42559
Location: 56N 3W

PostPosted: Sun May 01, 2016 2:26 pm    Post subject: Reply with quote

pacmac,

Well caught. The broadcast address is traditionally the highest address in the subnet. As long as its the same for all hosts on the subnet, it cam be anything.

The broadcast address is for well, broadcasting. You can't have a host on the broadcast address as every host is supposed to respond to some broadcast messages.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.
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