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Date:      Fri, 28 Jun 2002 19:06:55 -0600 (MDT)
From:      FreeBSD user <freebsd@XtremeDev.com>
To:        questions@freebsd.org
Subject:   OpenSSH 3.4p1_1 and reverse ip
Message-ID:  <20020628190401.E7121-200000@Amber.XtremeDev.com>

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Content-Type: TEXT/PLAIN; CHARSET=US-ASCII
Content-ID: <20020628190401.Q7121@Amber.XtremeDev.com>

After installing OpenSSH 3.4p1_1-portable (overwriting the one in base
with -DOPENSSH_OVERWRITE_BASE) and restarting it, /usr/sbin/sshd keeps
taking ~3-~5 minutes trying to reverse/resolve connecting client ips, even
though I specifically told it not to in /etc/ssh/sshd_config. On top of
which, the connecting ip IS reversable, I've checked with nslookup.
Attached is my sshd_config.

Another of note, I'm not using BIND, I'm using djbdns, both tinydns and
dnscache on the box running the sshd.


~> nslookup 192.168.1.2
Server:  ns.xtremedev.com
Address:  192.168.1.1

Name:  work.xtremedev.com
Address:  192.168.1.2


~> sudo /usr/sbin/sshd -d -d -d
debug1: sshd version OpenSSH_3.4p1
debug1: private host key: #0 type 0 RSA1
debug3: Not a RSA1 key file /etc/ssh/ssh_host_rsa_key.
debug1: read PEM private key done: type RSA
debug1: private host key: #1 type 1 RSA
debug3: Not a RSA1 key file /etc/ssh/ssh_host_dsa_key.
debug1: read PEM private key done: type DSA
debug1: private host key: #2 type 2 DSA
debug1: Bind to port 22 on 0.0.0.0.
Server listening on 0.0.0.0 port 22.
debug1: Server will not fork when running in debugging mode.
Connection from 192.168.1.2 port 2737
debug1: Client protocol version 2.0; client software version PuTTY-Release-0.52
debug1: no match: PuTTY-Release-0.52
Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_3.4p1
debug2: Network child is on pid 16762
debug3: privsep user:group 22:22
debug3: preauth child monitor started
debug1: list_hostkey_types: ssh-rsa,ssh-dss
debug3: mm_request_receive entering
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc@lysator.liu.se
debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,aes192-cbc,aes256-cbc,rijndael-cbc@lysator.liu.se
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96
debug2: kex_parse_kexinit: none,zlib
debug2: kex_parse_kexinit: none,zlib
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit: first_kex_follows 0
debug2: kex_parse_kexinit: reserved 0
debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-rsa,ssh-dss
debug2: kex_parse_kexinit: aes256-cbc,rijndael256-cbc,rijndael-cbc@lysator.liu.se,aes192-cbc,rijndael192-cbc,aes128-cbc,rijndael128-cbc,blowfish-cbc,3des-cbc
debug2: kex_parse_kexinit: aes256-cbc,rijndael256-cbc,rijndael-cbc@lysator.liu.se,aes192-cbc,rijndael192-cbc,aes128-cbc,rijndael128-cbc,blowfish-cbc,3des-cbc
debug2: kex_parse_kexinit: hmac-sha1,hmac-md5,none
debug2: kex_parse_kexinit: hmac-sha1,hmac-md5,none
debug2: kex_parse_kexinit: none,zlib,none
debug2: kex_parse_kexinit: none,zlib,none
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit: first_kex_follows 0
debug2: kex_parse_kexinit: reserved 0
debug2: mac_init: found hmac-sha1
debug1: kex: client->server aes256-cbc hmac-sha1 none
debug2: mac_init: found hmac-sha1
debug1: kex: server->client aes256-cbc hmac-sha1 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST_OLD received
debug3: mm_request_send entering: type 0
debug3: monitor_read: checking request 0
debug3: mm_choose_dh: waiting for MONITOR_ANS_MODULI
debug3: mm_answer_moduli: got parameters: 1024 2048 8192
debug3: mm_request_receive_expect entering: type 1
debug3: mm_request_receive entering
debug3: mm_request_send entering: type 1
debug3: mm_choose_dh: remaining 0
debug2: monitor_read: 0 used once, disabling now
debug1: SSH2_MSG_KEX_DH_GEX_GROUP sent
debug3: mm_request_receive entering
debug1: dh_gen_key: priv key bits set: 259/512
debug1: bits set: 994/2049
debug1: expecting SSH2_MSG_KEX_DH_GEX_INIT
debug1: bits set: 1062/2049
debug3: mm_key_sign entering
debug3: mm_request_send entering: type 4
debug3: monitor_read: checking request 4
debug3: mm_answer_sign
debug3: mm_key_sign: waiting for MONITOR_ANS_SIGN
debug3: mm_request_receive_expect entering: type 5
debug3: mm_request_receive entering
debug3: mm_answer_sign: signature 0x80a4c00(527)
debug3: mm_request_send entering: type 5
debug1: SSH2_MSG_KEX_DH_GEX_REPLY sent
debug1: kex_derive_keys
debug1: newkeys: mode 1
debug1: cipher_init: set keylen (16 -> 32)
debug1: SSH2_MSG_NEWKEYS sent
debug1: waiting for SSH2_MSG_NEWKEYS
debug2: monitor_read: 4 used once, disabling now
debug3: mm_request_receive entering
debug1: newkeys: mode 0
debug1: cipher_init: set keylen (16 -> 32)
debug1: SSH2_MSG_NEWKEYS received
debug1: KEX done
debug3: Trying to reverse map address 192.168.1.2.
Could not reverse map address 192.168.1.2.



You can see from ^^^^^^ (when I connect from my internal machine at
192.168.1.2, work.xtremedev.com) it can't resolve this. I have all my
firewall rules turned off (pass all) and name server running (djbdns).
nslookup is able to resolve the ip. But for some reason sshd can't. I even
explicitly told sshd not to reverse ip in /etc/ssh/sshd_config:

VerifyReverseMapping no

Can anyone see what I've missed? The client is able to connect
successfully after the elapsed time, it's just that horrid wait that the
user has to endure. If it wasn't for the exploit, I would immediately
backcvs to use the one that came with base rather than using the 3.4p1_1
port.

Thanks

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