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SSH works well but scp/rsync hangs!!!!

 

 

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mingfan.lu at gmail

Jun 24, 2010, 5:45 PM

Post #1 of 7 (5963 views)
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SSH works well but scp/rsync hangs!!!!

Two machine M1 and M2

*** in M1
scp file M2:/dir
Although it shows the file 100% transferred but scp hangs, I have to
use ctrl c to quit.
use -vvv options, I can get vvv.log as attachment.
It is very strange that scp only hangs when the size of file larger
than 1405B , if the size <=1405B, scp works well.
the attachment diff.log is the difference of the two logs of strace
(to sshd and its forks (process A and process B is the replacement of
forks))
The former (s1.log) is the strace log when transferring 1405B file
and the later (s2.log) is for 1406B
PS. I can use ssh to login M2 successfully.
*** In M2
scp file M1:/dir
it workswell!

Any ideas?
Attachments: diff.log (126 KB)
  s1.log (132 KB)
  s2.log (122 KB)
  vvv.log (7.87 KB)


andrej.groups at gmail

Jun 24, 2010, 9:18 PM

Post #2 of 7 (5850 views)
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Re: SSH works well but scp/rsync hangs!!!! [In reply to]

On 25 June 2010 12:45, Mingfan Lu <mingfan.lu [at] gmail> wrote:

> The former (s1.log) is the strace log when transferring 1405B file
> and the later (s2.log) is for 1406B
> PS. I can use ssh to login M2 successfully.
> *** In M2
> scp file M1:/dir
> it workswell!
>
> Any ideas?
The file size is suspiciously close to the default MTU .. any "odd" routers
along the way that may not like big packets?



Cheers,
Andrej


--
Please don't top post, and don't use HTML e-Mail :} Make your quotes concise.

http://www.georgedillon.com/web/html_email_is_evil.shtml


mingfan.lu at gmail

Jun 24, 2010, 10:39 PM

Post #3 of 7 (5848 views)
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Re: SSH works well but scp/rsync hangs!!!! [In reply to]

ifIchange the mtu of the interface in M2 from 1500 to 1496, all works ...
So strange

On Fri, Jun 25, 2010 at 12:18 PM, Andrej <andrej.groups [at] gmail> wrote:
> On 25 June 2010 12:45, Mingfan Lu <mingfan.lu [at] gmail> wrote:
>
>>   The former (s1.log) is the strace log when transferring 1405B file
>> and the later (s2.log) is for 1406B
>>  PS. I can use ssh to login M2 successfully.
>>   *** In M2
>>  scp file M1:/dir
>>  it works well!
>>
>>  Any ideas?
> The file size is suspiciously close to the default MTU .. any "odd" routers
> along the way that may not like big packets?
>
>
>
> Cheers,
> Andrej
>
>
> --
> Please don't top post, and don't use HTML e-Mail :}  Make your quotes concise.
>
> http://www.georgedillon.com/web/html_email_is_evil.shtml
>


m.hallgren at free

Jun 25, 2010, 1:07 AM

Post #4 of 7 (5845 views)
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Re: SSH works well but scp/rsync hangs!!!! [In reply to]

Le vendredi 25 juin 2010 à 13:39 +0800, Mingfan Lu a écrit :
> ifIchange the mtu of the interface in M2 from 1500 to 1496, all works ...
> So strange

broken pmtud

mh

>
> On Fri, Jun 25, 2010 at 12:18 PM, Andrej <andrej.groups [at] gmail> wrote:
> > On 25 June 2010 12:45, Mingfan Lu <mingfan.lu [at] gmail> wrote:
> >
> >> The former (s1.log) is the strace log when transferring 1405B file
> >> and the later (s2.log) is for 1406B
> >> PS. I can use ssh to login M2 successfully.
> >> *** In M2
> >> scp file M1:/dir
> >> it works well!
> >>
> >> Any ideas?
> > The file size is suspiciously close to the default MTU .. any "odd" routers
> > along the way that may not like big packets?
> >
> >
> >
> > Cheers,
> > Andrej
> >
> >
> > --
> > Please don't top post, and don't use HTML e-Mail :} Make your quotes concise.
> >
> > http://www.georgedillon.com/web/html_email_is_evil.shtml
> >


--
michael hallgren, mh2198-ripe
Attachments: signature.asc (0.19 KB)


mingfan.lu at gmail

Jun 25, 2010, 1:54 AM

Post #5 of 7 (5844 views)
Permalink
Re: SSH works well but scp/rsync hangs!!!! [In reply to]

How to fix broken the path mtu discovery?



2010/6/25 Michael Hallgren <m.hallgren [at] free>:
> Le vendredi 25 juin 2010 à 13:39 +0800, Mingfan Lu a écrit :
>> ifIchange the mtu of the interface in M2 from 1500 to 1496, all works ...
>> So strange
>
> broken pmtud
>
> mh
>
>>
>> On Fri, Jun 25, 2010 at 12:18 PM, Andrej <andrej.groups [at] gmail> wrote:
>> > On 25 June 2010 12:45, Mingfan Lu <mingfan.lu [at] gmail> wrote:
>> >
>> >>   The former (s1.log) is the strace log when transferring 1405B file
>> >> and the later (s2.log) is for 1406B
>> >>  PS. I can use ssh to login M2 successfully.
>> >>   *** In M2
>> >>  scp file M1:/dir
>> >>  it works well!
>> >>
>> >>  Any ideas?
>> > The file size is suspiciously close to the default MTU .. any "odd" routers
>> > along the way that may not like big packets?
>> >
>> >
>> >
>> > Cheers,
>> > Andrej
>> >
>> >
>> > --
>> > Please don't top post, and don't use HTML e-Mail :}  Make your quotes concise.
>> >
>> > http://www.georgedillon.com/web/html_email_is_evil.shtml
>> >
>
>
> --
> michael hallgren, mh2198-ripe
>


m.hallgren at free

Jun 25, 2010, 2:09 AM

Post #6 of 7 (5843 views)
Permalink
Re: SSH works well but scp/rsync hangs!!!! [In reply to]

Le vendredi 25 juin 2010 à 16:54 +0800, Mingfan Lu a écrit :
> How to fix broken the path mtu discovery?
>
>

Our friend (?) Google found this:

http://www.netheaven.com/pmtu.html

mh

>
> 2010/6/25 Michael Hallgren <m.hallgren [at] free>:
> > Le vendredi 25 juin 2010 à 13:39 +0800, Mingfan Lu a écrit :
> >> ifIchange the mtu of the interface in M2 from 1500 to 1496, all works ...
> >> So strange
> >
> > broken pmtud
> >
> > mh
> >
> >>
> >> On Fri, Jun 25, 2010 at 12:18 PM, Andrej <andrej.groups [at] gmail> wrote:
> >> > On 25 June 2010 12:45, Mingfan Lu <mingfan.lu [at] gmail> wrote:
> >> >
> >> >> The former (s1.log) is the strace log when transferring 1405B file
> >> >> and the later (s2.log) is for 1406B
> >> >> PS. I can use ssh to login M2 successfully.
> >> >> *** In M2
> >> >> scp file M1:/dir
> >> >> it works well!
> >> >>
> >> >> Any ideas?
> >> > The file size is suspiciously close to the default MTU .. any "odd" routers
> >> > along the way that may not like big packets?
> >> >
> >> >
> >> >
> >> > Cheers,
> >> > Andrej
> >> >
> >> >
> >> > --
> >> > Please don't top post, and don't use HTML e-Mail :} Make your quotes concise.
> >> >
> >> > http://www.georgedillon.com/web/html_email_is_evil.shtml
> >> >
> >
> >
> > --
> > michael hallgren, mh2198-ripe
> >


--
michael hallgren, mh2198-ripe
Attachments: signature.asc (0.19 KB)


david at blue-labs

Jun 25, 2010, 1:50 PM

Post #7 of 7 (5848 views)
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Re: SSH works well but scp/rsync hangs!!!! [In reply to]

https://blue-labs.org/howto/mtu-mss.php

On 06/25/10 04:54, Mingfan Lu wrote:
> How to fix broken the path mtu discovery?

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