> Start with the built in debugging:
>
> /usr/sbin/sshd -ddd
Output of /usr/sbin/sshd -ddd
debug2: load_server_config: filename /etc/ssh/sshd_config
debug2: load_server_config: done config len = 321
debug2: parse_server_config: config /etc/ssh/sshd_config len 321
debug1: sshd version OpenSSH_3.9p1
cipher_encrypt: bad plaintext length 337
>
> If that doesn't work, run it with strace directly.
>
> strace -x /usr/sbin/sshd -ddd
Output of strace -x /usr/sbin/sshd -ddd
execve("/usr/sbin/sshd", ["/usr/sbin/sshd", "-ddd"], [/* 32 vars */]) = 0
uname({sys="Linux", node="mail.sunupdelhi.net", ...}) = 0
brk(0) = 0x978c000
access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=56867, ...}) = 0
old_mmap(NULL, 56867, PROT_READ, MAP_PRIVATE, 3, 0) = 0xf6ff2000
close(3) = 0
open("/usr/lib/libwrap.so.0", O_RDONLY) = 3
read(3, "\x7f\x45\x4c\x46\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00"...,
512) = 51 2
fstat64(3, {st_mode=S_IFREG|0755, st_size=28504, ...}) = 0
old_mmap(0x7b4000, 27940, PROT_READ|PROT_EXEC,
MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7b4000
old_mmap(0x7ba000, 4096, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRI TE, 3, 0x6000) = 0x7ba000
close(3) = 0
open("/lib/libpam.so.0", O_RDONLY) = 3
read(3, "\x7f\x45\x4c\x46\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00"...,
512) = 51 2
fstat64(3, {st_mode=S_IFREG|0755, st_size=29344, ...}) = 0
old_mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS,
-1, 0) = 0 xf6ff1000
old_mmap(0x101000, 30812, PROT_READ|PROT_EXEC,
MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x101000
old_mmap(0x108000, 4096, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRI TE, 3, 0x6000) = 0x108000
close(3) = 0
open("/lib/libdl.so.2", O_RDONLY) = 3
read(3, "\x7f\x45\x4c\x46\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00"...,
512) = 51 2
fstat64(3, {st_mode=S_IFREG|0755, st_size=16908, ...}) = 0
old_mmap(0xc0f000, 12388, PROT_READ|PROT_EXEC,
MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xc0f000
old_mmap(0xc11000, 8192, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRI TE, 3, 0x1000) = 0xc11000
close(3) = 0
open("/lib/libcrypto.so.4", O_RDONLY) = 3
read(3, "\x7f\x45\x4c\x46\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00"...,
512) = 51 2
fstat64(3, {st_mode=S_IFREG|0755, st_size=957920, ...}) = 0
old_mmap(0x44fd000, 974136, PROT_READ|PROT_EXEC,
MAP_PRIVATE|MAP_DENYWRITE, 3, 0 ) = 0x44fd000
old_mmap(0x45d6000, 73728, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYW RITE, 3, 0xd8000) = 0x45d6000
old_mmap(0x45e8000, 11576, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONY MOUS, -1, 0) = 0x45e8000
close(3) = 0
open("/lib/libutil.so.1", O_RDONLY) = 3
read(3, "\x7f\x45\x4c\x46\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00"...,
512) = 51 2
fstat64(3, {st_mode=S_IFREG|0755, st_size=15956, ...}) = 0
old_mmap(0x9f1000, 12436, PROT_READ|PROT_EXEC,
MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x9f1000
old_mmap(0x9f3000, 8192, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRI TE, 3, 0x1000) = 0x9f3000
close(3) = 0
open("/usr/lib/libz.so.1", O_RDONLY) = 3
read(3, "\x7f\x45\x4c\x46\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00"...,
512) = 51 2
fstat64(3, {st_mode=S_IFREG|0755, st_size=63528, ...}) = 0
old_mmap(0xc15000, 65028, PROT_READ|PROT_EXEC,
MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xc15000
old_mmap(0xc24000, 4096, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRI TE, 3, 0xe000) = 0xc24000
close(3) = 0
open("/lib/libnsl.so.1", O_RDONLY) = 3
read(3, "\x7f\x45\x4c\x46\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00"...,
512) = 51 2
fstat64(3, {st_mode=S_IFREG|0755, st_size=96020, ...}) = 0
old_mmap(0x791000, 88288, PROT_READ|PROT_EXEC,
MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x791000
old_mmap(0x7a3000, 8192, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRI TE, 3, 0x11000) = 0x7a3000
old_mmap(0x7a5000, 6368, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMO US, -1, 0) = 0x7a5000
close(3) = 0
open("/lib/libcrypt.so.1", O_RDONLY) = 3
read(3, "\x7f\x45\x4c\x46\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00"...,
512) = 51 2
fstat64(3, {st_mode=S_IFREG|0755, st_size=28632, ...}) = 0
old_mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS,
-1, 0) = 0 xf6ff0000
old_mmap(0xa07000, 184636, PROT_READ|PROT_EXEC,
MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xa07000
old_mmap(0xa0c000, 8192, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRI TE, 3, 0x4000) = 0xa0c000
old_mmap(0xa0e000, 155964, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONY MOUS, -1, 0) = 0xa0e000
close(3) = 0
open("/lib/libselinux.so.1", O_RDONLY) = 3
read(3, "\x7f\x45\x4c\x46\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00"...,
512) = 51 2
fstat64(3, {st_mode=S_IFREG|0755, st_size=56288, ...}) = 0
old_mmap(0x75b000, 56140, PROT_READ|PROT_EXEC,
MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x75b000
old_mmap(0x768000, 4096, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRI TE, 3, 0xd000) = 0x768000
close(3) = 0
open("/usr/lib/libgssapi_krb5.so.2", O_RDONLY) = 3
read(3, "\x7f\x45\x4c\x46\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00"...,
512) = 51 2
fstat64(3, {st_mode=S_IFREG|0755, st_size=82944, ...}) = 0
old_mmap(0x5f4000, 80272, PROT_READ|PROT_EXEC,
MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x5f4000
old_mmap(0x607000, 4096, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRI TE, 3, 0x13000) = 0x607000
close(3) = 0
open("/usr/lib/libkrb5.so.3", O_RDONLY) = 3
read(3, "\x7f\x45\x4c\x46\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00"...,
512) = 51 2
fstat64(3, {st_mode=S_IFREG|0755, st_size=415188, ...}) = 0
old_mmap(0x60a000, 413000, PROT_READ|PROT_EXEC,
MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x60a000
old_mmap(0x66d000, 8192, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRI TE, 3, 0x63000) = 0x66d000
close(3) = 0
open("/usr/lib/libk5crypto.so.3", O_RDONLY) = 3
read(3, "\x7f\x45\x4c\x46\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00"...,
512) = 51 2
fstat64(3, {st_mode=S_IFREG|0755, st_size=136044, ...}) = 0
old_mmap(0x5d1000, 134560, PROT_READ|PROT_EXEC,
MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x5d1000
old_mmap(0x5f1000, 4096, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRI TE, 3, 0x20000) = 0x5f1000
close(3) = 0
open("/lib/libcom_err.so.2", O_RDONLY) = 3
read(3, "\x7f\x45\x4c\x46\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00"...,
512) = 51 2
fstat64(3, {st_mode=S_IFREG|0755, st_size=7004, ...}) = 0
old_mmap(0x5cc000, 8636, PROT_READ|PROT_EXEC,
MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x5cc000
old_mmap(0x5ce000, 4096, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRI TE, 3, 0x1000) = 0x5ce000
close(3) = 0
open("/lib/libresolv.so.2", O_RDONLY) = 3
read(3, "\x7f\x45\x4c\x46\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00"...,
512) = 51 2
fstat64(3, {st_mode=S_IFREG|0755, st_size=81316, ...}) = 0
old_mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS,
-1, 0) = 0 xf6fef000
old_mmap(0x220000, 80040, PROT_READ|PROT_EXEC,
MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x220000
mprotect(0x22f000, 18600, PROT_NONE) = 0
old_mmap(0x230000, 8192, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWRI TE, 3, 0xf000) = 0x230000
old_mmap(0x232000, 6312, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMO US, -1, 0) = 0x232000
close(3) = 0
open("/lib/tls/libc.so.6", O_RDONLY) = 3
read(3, "\x7f\x45\x4c\x46\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00"...,
512) = 51 2
fstat64(3, {st_mode=S_IFREG|0755, st_size=1512400, ...}) = 0
old_mmap(0xac1000, 1207532, PROT_READ|PROT_EXEC,
MAP_PRIVATE|MAP_DENYWRITE, 3, 0 ) = 0xac1000
old_mmap(0xbe2000, 16384, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_DENYWR ITE, 3, 0x120000) = 0xbe2000
old_mmap(0xbe6000, 7404, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_FIXED|MAP_ANONYMO US, -1, 0) = 0xbe6000
close(3) = 0
old_mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS,
-1, 0) = 0 xf6fee000
mprotect(0xc11000, 4096, PROT_READ) = 0
mprotect(0x9f3000, 4096, PROT_READ) = 0
mprotect(0x7a3000, 4096, PROT_READ) = 0
mprotect(0xa0c000, 4096, PROT_READ) = 0
mprotect(0x230000, 4096, PROT_READ) = 0
mprotect(0xbe2000, 8192, PROT_READ) = 0
mprotect(0xabd000, 4096, PROT_READ) = 0
set_thread_area({entry_number:-1 -> 6, base_addr:0xf6feeaa0,
limit:1048575, seg_ 32bit:1, contents:0, read_exec_only:0,
limit_in_pages:1, seg_not_present:0, usea ble:1}) = 0
munmap(0xf6ff2000, 56867) = 0
access("/etc/selinux/", F_OK) = 0
brk(0) = 0x978c000
brk(0x97ad000) = 0x97ad000
open("/etc/selinux/config", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=447, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
0) = 0xf6 fff000
read(3, "# This file controls the state o"..., 4096) = 447
close(3) = 0
munmap(0xf6fff000, 4096) = 0
open("/proc/mounts", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
0) = 0xf6 fff000
read(3, "rootfs / rootfs rw 0 0\n/proc /pr"..., 1024) = 489
read(3, "", 1024) = 0
close(3) = 0
munmap(0xf6fff000, 4096) = 0
setgroups32(0, []) = 0
geteuid32() = 0
setgroups32(0, []) = 0
getpid() = 6931
open("/proc/6931/fd", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY) = 3
fstat64(3, {st_mode=S_IFDIR|0500, st_size=0, ...}) = 0
fcntl64(3, F_SETFD, FD_CLOEXEC) = 0
getdents64(3, /* 6 entries */, 1024) = 144
getdents64(3, /* 0 entries */, 1024) = 0
close(3) = 0
open("/dev/urandom", O_RDONLY|O_NONBLOCK|O_NOCTTY) = 3
select(4, [3], NULL, NULL, {0, 10000}) = 1 (in [3], left {0, 10000})
read(3, "\x7c\x09\x50\x20\x0e\xf1\x82\x9c\x37\xe0\xef\x92\xef\xce"..., 32) = 32
close(3) = 0
getuid32() = 0
time(NULL) = 1117514671
write(2, "debug2: load_server_config: file"..., 59debug2:
load_server_config: fi lename /etc/ssh/sshd_config
) = 59
open("/etc/ssh/sshd_config", O_RDONLY|O_LARGEFILE) = 3
fstat64(3, {st_mode=S_IFREG|0600, st_size=3025, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1,
0) = 0xf6 fff000
read(3, "#\t$OpenBSD: sshd_config,v 1.69 2"..., 4096) = 3025
read(3, "", 4096) = 0
close(3) = 0
munmap(0xf6fff000, 4096) = 0
write(2, "debug2: load_server_config: done"..., 51debug2:
load_server_config: do ne config len = 321
) = 51
write(2, "debug2: parse_server_config: con"..., 66debug2:
parse_server_config: c onfig /etc/ssh/sshd_config len 321
) = 66
socket(PF_INET6, SOCK_DGRAM, IPPROTO_IP) = 3
connect(3, {sa_family=AF_INET6, sin6_port=htons(22),
inet_pton(AF_INET6, "::", & sin6_addr), sin6_flowinfo=0,
sin6_scope_id=0}, 28) = 0
getsockname(3, {sa_family=AF_INET6, sin6_port=htons(34499),
inet_pton(AF_INET6, "::1", &sin6_addr), sin6_flowinfo=0,
sin6_scope_id=0}, [28]) = 0
close(3) = 0
socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3
connect(3, {sa_family=AF_INET, sin_port=htons(22),
sin_addr=inet_addr("0.0.0.0") }, 16) = 0
getsockname(3, {sa_family=AF_INET, sin_port=htons(34499),
sin_addr=inet_addr("12 7.0.0.1")}, [16]) = 0
close(3) = 0
write(2, "debug1: sshd version OpenSSH_3.9"..., 36debug1: sshd version
OpenSSH_3 .9p1
) = 36
open("/etc/ssh/ssh_host_key", O_RDONLY|O_LARGEFILE) = 3
fstat64(3, {st_mode=S_IFREG|0600, st_size=516, ...}) = 0
getuid32() = 0
fstat64(3, {st_mode=S_IFREG|0600, st_size=516, ...}) = 0
read(3, "SSH PRIVATE KEY FILE FORMAT 1.1\n"..., 516) = 516
_llseek(3, 0, [0], SEEK_SET) = 0
fstat64(3, {st_mode=S_IFREG|0600, st_size=516, ...}) = 0
read(3, "SSH PRIVATE KEY FILE FORMAT 1.1\n"..., 516) = 516
write(2, "cipher_encrypt: bad plaintext le"..., 42cipher_encrypt: bad
plaintext length 337
) = 42
exit_group(255) = ?
Thanks for your efforts.
Thanks & Regards'
Ankush Grover
