Changes between Version 84 and Version 85 of SftpFrontend


Ignore:
Timestamp:
2013-05-23T16:30:39Z (8 years ago)
Author:
daira
Comment:

update information on rekeying bug and Twisted compatibility for Tahoe-LAFS v1.10

Legend:

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  • SftpFrontend

    v84 v85  
    2727The '{{{ctime}}}' and '{{{mtime}}}' attributes will always be the same, and are set from the Tahoe {{{linkmotime}}} timestamp, which is changed only when the link from the parent directory is modified (see the [http://tahoe-lafs.org/trac/tahoe-lafs/browser/docs/frontends/webapi.rst#about-the-metadata 'About the metadata' section of webapi.rst]). These fields are not updated when the contents of a mutable file are changed. The SFTP protocol and the server are able to represent dates up to the year 2106, but some clients may print dates incorrectly after 2037.
    2828
    29 Versions of Twisted before 11.0 have [http://twistedmatrix.com/trac/ticket/4395 a bug in support for rekeying]. This might cause a hang or 100% CPU usage by the gateway when a client tries to rekey. Depending on the client, rekeying may be triggered based on a time interval or the amount of data sent (for example, 1 GiB to 4 GiB for the openssh client), so this problem may not happen immediately when testing. Tahoe-LAFS v1.10 will require Twisted >= 11.0 to avoid this problem; in the meantime, we recommend that you either:
    30 * Install Twisted 11.0 or later manually (if it is not already installed), or
    31 * Use an option in your client to disable rekeying. For example in WinSCP, in the Key exchange section of the options under SSH, set both 'Max minutes before rekey' and 'Max data before rekey' to 0. Note that OpenSSH and sshfs do not seem to have an option to do this that works, contrary to what a previous version of this page said.
     29Versions of Twisted before 11.0 have [http://twistedmatrix.com/trac/ticket/4395 a bug in support for rekeying]. Tahoe-LAFS v1.10.0 requires a later version of Twisted and so will not be affected by this problem. For earlier versions of Tahoe-LAFS, it is recommended to install a version of Twisted between v11.0 and v12.2 inclusive (and use {{{tahoe --version}}} to check that it is being used); otherwise, this bug might cause a hang or 100% CPU usage by the gateway when a client tries to rekey. Depending on the client, rekeying may be triggered based on a time interval or the amount of data sent (for example, 1 GiB to 4 GiB for the openssh client), so this problem may not happen immediately when testing.
    3230
    33 Disabling rekeying [http://winscp.net/eng/docs/ui_login_kex#reexchange might introduce cryptographic weaknesses], so updating Twisted is the preferred solution.
     31Version v12.3 of Twisted is incompatible with the SFTP frontend (#1926, #1525). Upgrade to Tahoe-LAFS v1.10 to fix this problem.
    3432
    3533