username@server:~$ sudo /etc/init.d/ssh stop
 * Stopping OpenBSD Secure Shell server sshd                             [ OK ] 
username@server:~$ cd /usr/bin/
username@server:/usr/bin$ sudo gdb sshd
GNU gdb 6.8-debian
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "i486-linux-gnu"...
(no debugging symbols found)
(gdb) run -d
Starting program: /usr/sbin/sshd -d
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
[Thread debugging using libthread_db enabled]
debug1: sshd version OpenSSH_5.1p1 Debian-5ubuntu1
[New Thread 0xb7b36ac0 (LWP 5138)]
(no debugging symbols found)
---Type <return> to continue, or q <return> to quit---
(no debugging symbols found)
(no debugging symbols found)
debug1: read PEM private key done: type RSA
debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048
debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048
debug1: private host key: #0 type 1 RSA
debug1: read PEM private key done: type DSA
debug1: Checking blacklist file /usr/share/ssh/blacklist.DSA-1024
debug1: Checking blacklist file /etc/ssh/blacklist.DSA-1024
debug1: private host key: #1 type 2 DSA
debug1: rexec_argv[0]='/usr/sbin/sshd'
debug1: rexec_argv[1]='-d'
debug1: Bind to port 22 on 0.0.0.0.
Server listening on 0.0.0.0 port 22.
debug1: Bind to port 22 on ::.
Server listening on :: port 22.
debug1: Server will not fork when running in debugging mode.
debug1: rexec start in 5 out 5 newsock 5 pipe -1 sock 8
[New process 5138]
Executing new program: /usr/sbin/sshd
(no debugging symbols found)
warning: Cannot initialize thread debugging library: generic error
warning: Cannot initialize thread debugging library: generic error
(no debugging symbols found)
[New process 5138]
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
[Thread debugging using libthread_db enabled]
Segmentation fault
username@server:/usr/bin$ debug1: inetd sockets after dupping: 3, 3
Connection from 192.168.1.10 port 43663
debug1: Client protocol version 2.0; client software version OpenSSH_4.2
debug1: match: OpenSSH_4.2 pat OpenSSH_4*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.1p1 Debian-5ubuntu1
debug1: permanently_set_uid: 110/65534
debug1: list_hostkey_types: ssh-rsa,ssh-dss
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: client->server aes128-cbc hmac-md5 none
debug1: kex: server->client aes128-cbc hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST received
debug1: SSH2_MSG_KEX_DH_GEX_GROUP sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_INIT
debug1: SSH2_MSG_KEX_DH_GEX_REPLY sent
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: KEX done
debug1: userauth-request for user username service ssh-connection method none
debug1: attempt 0 failures 0
debug1: PAM: initializing for "username"
debug1: PAM: setting PAM_RHOST to "ferrer.ac.upc.es"
debug1: PAM: setting PAM_TTY to "ssh"
Failed none for username from 192.168.1.10 port 43663 ssh2
debug1: userauth-request for user username service ssh-connection method password
debug1: attempt 1 failures 0
Error: Bad address.
*** glibc detected *** sshd: username [priv]: malloc(): memory corruption: 0xb87f1270 ***
======= Backtrace: =========
/lib/tls/i686/cmov/libc.so.6[0xb7bc4276]
/lib/tls/i686/cmov/libc.so.6(__libc_malloc+0x95)[0xb7bc59c5]
/lib/libpam.so.0(pam_modutil_getpwnam+0x3e)[0xb7f8914e]
/lib/security/pam_unix.so[0xb79847bc]
/lib/security/pam_unix.so[0xb79848c1]
/lib/security/pam_unix.so[0xb79823dd]
/lib/security/pam_unix.so(pam_sm_authenticate+0x2bd)[0xb797fdfd]
/lib/libpam.so.0[0xb7f843b1]
/lib/libpam.so.0(pam_authenticate+0x4d)[0xb7f83bdd]
sshd: username [priv][0xb7ff3586]
sshd: username [priv][0xb7fd528f]
sshd: username [priv][0xb7fea327]
sshd: username [priv][0xb7feab0e]
sshd: username [priv][0xb7feb589]
sshd: username [priv](main+0x2d59)[0xb7fd3e99]
/lib/tls/i686/cmov/libc.so.6(__libc_start_main+0xe5)[0xb7b68775]
sshd: username [priv][0xb7fcff51]
======= Memory map: ========
b695c000-b6969000 r-xp 00000000 08:01 1573102    /lib/libgcc_s.so.1
b6969000-b696a000 r--p 0000c000 08:01 1573102    /lib/libgcc_s.so.1
b696a000-b696b000 rw-p 0000d000 08:01 1573102    /lib/libgcc_s.so.1
b697b000-b697c000 ---p b697b000 00:00 0 
b697c000-b717c000 rw-p b697c000 00:00 0 
b717c000-b717d000 ---p b717c000 00:00 0 
b717d000-b797d000 rw-p b717d000 00:00 0 
b797d000-b7989000 r-xp 00000000 08:01 1573398    /lib/security/pam_unix.so
b7989000-b798a000 r--p 0000b000 08:01 1573398    /lib/security/pam_unix.so
b798a000-b798b000 rw-p 0000c000 08:01 1573398    /lib/security/pam_unix.so
b798b000-b7997000 rw-p b798b000 00:00 0 
b7997000-b799d000 r-xp 00000000 08:01 1572935    /lib/libusb-0.1.so.4.4.4
b799d000-b799e000 r--p 00005000 08:01 1572935    /lib/libusb-0.1.so.4.4.4
b799e000-b79a0000 rw-p 00006000 08:01 1572935    /lib/libusb-0.1.so.4.4.4
b79a1000-b79a4000 r-xp 00000000 08:01 1573377    /lib/security/pam_limits.so
b79a4000-b79a5000 r--p 00003000 08:01 1573377    /lib/security/pam_limits.so
b79a5000-b79a6000 rw-p 00004000 08:01 1573377    /lib/security/pam_limits.so
b79a6000-b79a8000 r-xp 00000000 08:01 1573381    /lib/security/pam_mail.so
b79a8000-b79a9000 r--p 00001000 08:01 1573381    /lib/security/pam_mail.so
b79a9000-b79aa000 rw-p 00002000 08:01 1573381    /lib/security/pam_mail.so
b79aa000-b79ab000 r-xp 00000000 08:01 1573383    /lib/security/pam_motd.so
b79ab000-b79ac000 r--p 00000000 08:01 1573383    /lib/security/pam_motd.so
b79ac000-b79ad000 rw-p 00001000 08:01 1573383    /lib/security/pam_motd.so
b79ad000-b79ae000 r-xp 00000000 08:01 1573385    /lib/security/pam_nologin.so
b79ae000-b79af000 r--p 00000000 08:01 1573385    /lib/security/pam_nologin.so
b79af000-b79b0000 rw-p 00001000 08:01 1573385    /lib/security/pam_nologin.so
b79b0000-b79b5000 r-xp 00000000 08:01 1573057    /lib/tls/i686/cmov/libnss_dns-2.9.so
b79b5000-b79b6000 r--p 00004000 08:01 1573057    /lib/tls/i686/cmov/libnss_dns-2.9.so
b79b6000-b79b7000 rw-p 00005000 08:01 1573057    /lib/tls/i686/cmov/libnss_dns-2.9.so
b79b7000-b79b9000 r-xp 00000000 08:01 8749802    /lib/libnss_mdns4_minimal.so.2
b79b9000-b79ba000 rw-p 00001000 08:01 8749802    /lib/libnss_mdns4_minimal.so.2
b79bb000-b79be000 r-xp 00000000 08:01 1771250    /usr/local/lib/libthinkfinger.so.0.0.0
b79be000-b79bf000 rw-p 00002000 08:01 1771250    /usr/local/lib/libthinkfinger.so.0.0.0
b79bf000-b79c2000 r-xp 00000000 08:01 1577166    /lib/security/pam_thinkfinger.so
b79c2000-b79c3000 rw-p 00002000 08:01 1577166    /lib/security/pam_thinkfinger.so
b79c4000-b79c7000 r-xp 00000000 08:01 1573301    /lib/security/pam_env.so
b79c7000-b79c8000 r--p 00002000 08:01 1573301    /lib/security/pam_env.so
b79c8000-b79c9000 rw-p 00003000 08:01 1573301    /lib/security/pam_env.so
b79ca000-b7b0a000 rw-s 00000000 00:09 57791      /dev/zero (deleted)
b7b0a000-b7b14000 r-xp 00000000 08:01 1573060    /lib/tls/i686/cmov/libnss_files-2.9.so
b7b14000-b7b15000 r--p 00009000 08:01 1573060    /lib/tls/i686/cmov/libnss_files-2.9.so
b7b15000-b7b16000 rw-p 0000a000 08:01 1573060    /lib/tls/i686/cmov/libnss_files-2.9.so
b7b16000-b7b1f000 r-xp 00000000 08:01 1573065    /lib/tls/i686/cmovdebug1: do_cleanup
username@server:/usr/bin$