New: New cache learned PMTU information in inetpeer causes ssh to fail when tunneled via an IPSEC VPN

Bugme-new Andrew Morton 1 participant 1 message Jun 6, 2011 1 message not in the archive

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Andrew Morton

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2011-06-06 20:49 UTC #1 lore raw

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Quoted 36 lines · On Sat, 28 May 2011 21:50:32 GMT [email protected] wrote:

https://bugzilla.kernel.org/show_bug.cgi?id=36122
               URL: http://bugs.gentoo.org/show_bug.cgi?id=369025
           Summary: New cache learned PMTU information in inetpeer causes
                    ssh to fail when tunneled via an IPSEC VPN
           Product: Networking
           Version: 2.5
    Kernel Version: 2.6.39
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: IPV4
        AssignedTo: [email protected]
        ReportedBy: [email protected]
                CC: [email protected]
        Regression: No
When trying to ssh from a box running 2.6.39 on one private subnet to another box on another private subnet via an IPSEC vpn, ssh freezes and times out at:
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
This was traced down to commit 2c8cec5c10bced2408082a6656170e74ac17231c.
This type of error is known to occur when there is fragmentation due to mismatched mtu's which the commit addresses.
Notice the problem does not occur when ssh-ing directly, ie not via an IPSEC tunnel. I have not tested if other tunnels are affected.
Please see the downstream bug for more details.