Problems updating BubbaTwo

[jonj1]

On the other hand, I can wget files over the LAN - this is connecting to my old home server:

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# wget http://puffin/
--10:25:35--  http://puffin/
           => `index.html'
Resolving puffin... 192.168.1.64
Connecting to puffin|192.168.1.64|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1,457 (1.4K) [text/html]

100%[========================================================================================>] 1,457         --.--K/s             

10:25:35 (16.52 MB/s) - `index.html' saved [1457/1457]

Likewise I can ssh to boxes on the LAN, but not over the WAN. This is an ssh connection to a WAN server (known to be working)

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$ ssh -vv <user>@<host>.ac.uk
OpenSSH_4.3p2 Debian-9etch3ex1, OpenSSL 0.9.8c 05 Sep 2006
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to <host>.ac.uk [144.82.110.1] port 22.
debug1: Connection established.
debug1: identity file /home/<bubba user>/.ssh/identity type -1
debug1: identity file /home/<bubba user>/.ssh/id_rsa type -1
debug1: identity file /home/<bubba user>/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version Sun_SSH_1.1
debug1: no match: Sun_SSH_1.1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_4.3p2 Debian-9etch3ex1
debug2: fd 3 setting O_NONBLOCK
debug1: Miscellaneous failure
No credentials cache found

debug1: Miscellaneous failure
No credentials cache found

debug1: SSH2_MSG_KEXINIT sent

[jonj1]

hmm looks like DNS resolves,
but TCP connection fails
or NAT doesn't work
what is your setup?
internet connection direct into B2?
or internet -> router -> B2 ?

internet > wireless router
router > bubba LAN port
router > PC etc.

bubba configuration is for automatic IP assignment for both WAN and LAN.

[pa]

Hi guys,

Are you using cable modems?
Please also check this thread:
http://forum.excito.net/viewtopic.php?t=1226

Cable modems are sometimes using a bit "non-standard" but within specifications for the mtu setting. In the next upgrade there is a fix that hopefully will solve that problem.

/PA, Excito

[jonj1]

Hi guys,

Are you using cable modems?
Please also check this thread:
http://forum.excito.net/viewtopic.php?t=1226

Cable modems are sometimes using a bit "non-standard" but within specifications for the mtu setting. In the next upgrade there is a fix that hopefully will solve that problem.

/PA, Excito

Thanks for the suggestion. My ADSL modem is built in to the wireless router so I don't know if it's applicable. I tried these two commands anyway and it doesn't seem to help

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ifconfig eth1 mtu 576 
ifconfig eth1 mtu 1500

[pa]

Hi again,

I noted that you tried the workaround for the silicon bug, but can I ask you to run it once again (on LAN).

ethtool --offload eth1 rx off tx off

If you have rebooted bubba, this setting is not remembered. Usually this bug is not a problem on the LAN, but if your router does change the ports used in the communiation with bubba and the outside world, it is possible that this error can pass through the router.

/PA.

PS. If this solution works for you, update the software then edit the file /etc/init.d/disable-offload to disable offload on eth1 instead of eth0. This edit will make the workaround permanent.

[jonj1]

Hi again,

I noted that you tried the workaround for the silicon bug, but can I ask you to run it once again (on LAN).

ethtool --offload eth1 rx off tx off

Thanks again for the help. I rebooted bubba and ran the command above as root but apt-get update and wget www.google.com still time out as before. I wonder if an

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iptables --flush

would help here? Is it safe to run this without messing up the web-based configuration utility?

[pa]

Hi,

Flushing the iptables chains will actually render bubba inaccessible, so do not do that!
The default policy of the input chain is to drop all incoming packets, so withouthe rules all packets will be dropped!

I have send an email to you, please read this and come back to me.

/PA, Excito

[jonj1]

Many thanks to PA for tracking this down. It appears to be a problem with tcp checksumming on certain routers. The solution for my bubba behind a speedtouch 716 router was to

• connect to bubba over SSH (there's a free SSH program called 'putty' for windows)
  become root with the command: 'su' and root password (excito by default)
  Type the following command and press Enter (no output is printed to the screen):

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echo 0 > /proc/sys/net/ipv4/tcp_window_scaling

[pa]

Hi,

A bit more information about this issue:

I do think that this is a problem related to that the router does not handle tcp window scaling correctly. Disabling tcp checks in the router also made the system work, but altering the router configuration is not anything easyly done, finding this setting was quite tricky.

Also, note that for this workaround to take permanently this setting has to be added to /etc/sysctl.conf otherwise it will be lost at reboot.

/PA