Openvpn hanging?

[Rick Stevens]

On 09/10/2013 05:10 AM, Reindl Harald issued this missive:
>
>
> Am 10.09.2013 14:05, schrieb Timothy Murphy:
>> fedora wrote:
>>
>>>> I'm having a curious problem communicating with a remote site of mine.
>>>> I can access the site with "ssh -Y alfred-vpn" without any problem.
>>>> But then any command, eg cat, vim, tail,
>>>> that gives more than a minimal response,
>>>> causes the connection to hang, that is, to cease accepting any input,
>>>> and I see no way to revive the connection
>>>> except to kill the sshd entry from another ssh connection to the site,
>>>> or else just to close the local window.
>>>>
>>>> For example, "sudo tail -9 /var/log/messages" works,
>>>> but not if I replace 9 with 20.[tim at alfred ~]$ ifconfig tun0
>>
>>> Different MTU and fragmentation disabled?
>>
>> Thanks for your response.
>> But the MTU seems to be 1500 at both ends
>> (unless the modem at the remote end can change it?)
>
> that may be true, but we have a cisco router from out ISP
> which does not like this on a 100Mbit fiber connection
>
> i had to reduce the MTU for openvpn to 1472 on the openvpn
> server as well as on the clieints and the problem you are
> describing went away

Yes, there are some routers and such that have issues with 1500 byte
MTUs. VPNC allows you to do:

	NAT Traversal Mode cisco-udp

to get around it. I've had to use it in several hotels in the past.
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- Rick Stevens, Systems Engineer, AllDigital    ricks at alldigital.com -
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