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The well known and used ssh server Dropbear has a maximum SSH packet length at 32768 by default. Since the libssh2 design current have a fixed one-to-one mapping from channel_write() to the packet size created by transport_write() the previous limit of 32768 in the channel layer caused the transport layer to create larger packets than 32768 at times which Dropbear rejected forcibly (by closing the connection). The long term fix is of course to remove the hard relation between the outgoing SSH packet size and what the input length argument is in the transport_write() function call.
libssh2 - SSH2 library ====================== libssh2 is a library implementing the SSH2 protocol, available under the revised BSD license. Web site: http://www.libssh2.org/ Mailing list: http://cool.haxx.se/mailman/listinfo/libssh2-devel Generic installation instructions are in INSTALL. Some ./configure options deserve additional comments: * --enable-crypt-none The SSH2 Transport allows for unencrypted data transmission using the "none" cipher. Because this is such a huge security hole, it is typically disabled on SSH2 implementations and is disabled in libssh2 by default as well. Enabling this option will allow for "none" as a negotiable method, however it still requires that the method be advertized by the remote end and that no more-preferable methods are available. * --enable-mac-none The SSH2 Transport also allows implementations to forego a message authentication code. While this is less of a security risk than using a "none" cipher, it is still not recommended as disabling MAC hashes removes a layer of security. Enabling this option will allow for "none" as a negotiable method, however it still requires that the method be advertized by the remote end and that no more-preferable methods are available. * --disable-gex-new The diffie-hellman-group-exchange-sha1 (dh-gex) key exchange method originally defined an exchange negotiation using packet type 30 to request a generation pair based on a single target value. Later refinement of dh-gex provided for range and target values. By default libssh2 will use the newer range method. If you experience trouble connecting to an old SSH server using dh-gex, try this option to fallback on the older more reliable method. * --with-libgcrypt * --without-libgcrypt * --with-libgcrypt-prefix=DIR libssh2 can use the Libgcrypt library (http://www.gnupg.org/) for cryptographic operations. Either Libgcrypt or OpenSSL is required. Configure will attempt to locate Libgcrypt automatically. If your installation of Libgcrypt is in another location, specify it using --with-libgcrypt-prefix. * --with-openssl * --without-openssl * --with-libssl-prefix=[DIR] libssh2 can use the OpenSSL library (http://www.openssl.org) for cryptographic operations. Either Libgcrypt or OpenSSL is required. Configure will attempt to locate OpenSSL in the default location. If your installation of OpenSSL is in another location, specify it using --with-libssl-prefix. * --with-libz * --without-libz * --with-libz-prefix=[DIR] If present, libssh2 will attempt to use the zlib (http://www.zlib.org) for payload compression, however zlib is not required. If your installation of Libz is in another location, specify it using --with-libz-prefix. * --enable-debug Will make the build use more pedantic and strict compiler options as well as enable the libssh2_trace() function (for showing debug traces).