[Bug 708493] Re: cannot login anymore: Read from socket failed: Connection reset by peer

[Ralf Hildebrandt]

Sooo, I found this. All the failing systems have

ii  libssl1.0.0                       1.0.0c-2
SSL shared libraries

installed (I compiled Postfix against openssl-1.0.0, that's why it's
installed), yet their sshd is not linked against libssl1.0.0:

mail:~# ldd /usr/sbin/sshd
	linux-gate.so.1 =>  (0xb774f000)
	libwrap.so.0 => /lib/libwrap.so.0 (0xb76c2000)
	libpam.so.0 => /lib/libpam.so.0 (0xb76b6000)
	libselinux.so.1 => /lib/libselinux.so.1 (0xb769a000)
	libcrypto.so.0.9.8 => /usr/lib/i686/cmov/libcrypto.so.0.9.8 (0xb7542000)
	libutil.so.1 => /lib/i686/cmov/libutil.so.1 (0xb753e000)
	libz.so.1 => /usr/lib/libz.so.1 (0xb752a000)
	libcrypt.so.1 => /lib/i686/cmov/libcrypt.so.1 (0xb74f8000)
	libgssapi_krb5.so.2 => /usr/lib/libgssapi_krb5.so.2 (0xb74c8000)
	libkrb5.so.3 => /usr/lib/libkrb5.so.3 (0xb7416000)
	libcom_err.so.2 => /lib/libcom_err.so.2 (0xb7413000)
	libc.so.6 => /lib/i686/cmov/libc.so.6 (0xb72cd000)
	libnsl.so.1 => /lib/i686/cmov/libnsl.so.1 (0xb72b6000)
	libdl.so.2 => /lib/i686/cmov/libdl.so.2 (0xb72b1000)
	/lib/ld-linux.so.2 (0xb7750000)
	libk5crypto.so.3 => /usr/lib/libk5crypto.so.3 (0xb728e000)
	libkrb5support.so.0 => /usr/lib/libkrb5support.so.0 (0xb7287000)
	libkeyutils.so.1 => /lib/libkeyutils.so.1 (0xb7284000)
	libresolv.so.2 => /lib/i686/cmov/libresolv.so.2 (0xb7270000)
	libpthread.so.0 => /lib/i686/cmov/libpthread.so.0 (0xb7256000)

The verbose output indicates this immediately before failure:

...
debug1: sending SSH2_MSG_KEX_ECDH_INIT
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
Read from socket failed: Connection reset by peer

ECDH being elliptical curve diffie hellman -- but one needs openssl-1.0.0 (or at least 0.9.9) for that.
Since sshd is not linked against 1.0.0, it cannot handle ECC (elliptical curve cryptography) at all.

But the real question is: Why is ECC being used if ONE of the two sides
doesn't support it?!

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https://bugs.launchpad.net/bugs/708493

Title:
  cannot login anymore: Read from socket failed: Connection reset by
  peer