Take the 2-minute tour ×
Unix & Linux Stack Exchange is a question and answer site for users of Linux, FreeBSD and other Un*x-like operating systems.. It's 100% free, no registration required.

I have enabled X forwarding on remote machine where SSH server is running:

# grep -i forward /etc/ssh/sshd_config 
X11Forwarding yes
# 

On local machine, I have started SSH client with -X flag which instructs the SSH server, running on remote machine, to set up a X-server proxy. In addition, it creates the $DISPLAY variable which points to this proxy and calls the xauth to install a proxy key which authenticates to this X-server proxy on remote machine:

# echo "$DISPLAY"
localhost:11.0
# xauth list | grep 11
A58/unix:11  MIT-MAGIC-COOKIE-1  39324086672d1ae35e373476c3891a77
# 

However, X clients on remote machine do not start properly:

# wireshark 

(wireshark:10083): Gtk-WARNING **: cannot open display: localhost:11.0
# xterm
Warning: This program is an suid-root program or is being run by the root user.
The full text of the error or warning message cannot be safely formatted
in this environment. You may get a more descriptive message by running the
program as a non-root user or by removing the suid bit on the executable.
xterm: Xt error: Can't open display: %s
# 

X forwarding doesn't use xhost so at least this can be excluded. I tried to find some useful log entries both on machine where SSH server is running and machine where SSH client is running with find /var/log/ -mmin -5 -type f command, but this did not give any hints. SSH server version is OpenSSH_5.9p1 and SSH client version is OpenSSH_5.2p1. Output of /tmp/.X11-unix/ directory on remote machine can be seen below:

# ls -la /tmp/.X11-unix/
total 0
drwxrwxrwt 2 root root 40 Dec  9 15:44 .
drwxrwxrwt 4 root root 80 Jan 13 09:17 ..
# 

As seen above, there are no Unix domain sockets there. Output of strace xterm is following:

# strace xterm 
execve("/usr/bin/xterm", ["xterm"], [/* 16 vars */]) = 0
brk(0)                                  = 0x9e50000
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
mmap2(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb77bd000
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=42995, ...}) = 0
mmap2(NULL, 42995, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb77b2000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/i386-linux-gnu/libXft.so.2", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\3604\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=82952, ...}) = 0
mmap2(NULL, 85732, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb779d000
mmap2(0xb77b1000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x13) = 0xb77b1000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/i386-linux-gnu/libXaw.so.7", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\300\327\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=428900, ...}) = 0
mmap2(NULL, 432592, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7733000
mmap2(0xb7796000, 28672, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x62) = 0xb7796000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/libutempter.so.0", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\360\6\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=4572, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7732000
mmap2(NULL, 7432, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7730000
mmap2(0xb7731000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0) = 0xb7731000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/i386-linux-gnu/libtinfo.so.5", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0Pd\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=125416, ...}) = 0
mmap2(NULL, 129100, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7710000
mmap2(0xb772d000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1c) = 0xb772d000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/i386-linux-gnu/i686/cmov/libc.so.6", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\240o\1\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0755, st_size=1413288, ...}) = 0
mmap2(NULL, 1427832, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb75b3000
mprotect(0xb7709000, 4096, PROT_NONE)   = 0
mmap2(0xb770a000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x156) = 0xb770a000
mmap2(0xb770d000, 10616, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb770d000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/i386-linux-gnu/libfontconfig.so.1", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\300J\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=215828, ...}) = 0
mmap2(NULL, 219492, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb757d000
mmap2(0xb75b1000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x33) = 0xb75b1000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/i386-linux-gnu/libX11.so.6", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\240g\1\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=1273544, ...}) = 0
mmap2(NULL, 1277496, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7445000
mmap2(0xb7579000, 16384, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x133) = 0xb7579000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/i386-linux-gnu/libXmu.so.6", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\200N\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=102028, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7444000
mmap2(NULL, 101644, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb742b000
mmap2(0xb7443000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x18) = 0xb7443000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/i386-linux-gnu/libXt.so.6", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0000\315\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=380284, ...}) = 0
mmap2(NULL, 380628, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb73ce000
mmap2(0xb7427000, 16384, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x59) = 0xb7427000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/i386-linux-gnu/libICE.so.6", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\300:\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=92148, ...}) = 0
mmap2(NULL, 102224, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb73b5000
mmap2(0xb73cb000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x15) = 0xb73cb000
mmap2(0xb73cd000, 3920, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb73cd000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/i386-linux-gnu/libfreetype.so.6", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\320\202\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=632928, ...}) = 0
mmap2(NULL, 635732, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7319000
mmap2(0xb73b0000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x96) = 0xb73b0000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/i386-linux-gnu/libXrender.so.1", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0p\25\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=35744, ...}) = 0
mmap2(NULL, 38540, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb730f000
mmap2(0xb7318000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x8) = 0xb7318000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/i386-linux-gnu/libXext.so.6", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0`,\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=70320, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb730e000
mmap2(NULL, 73416, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb72fc000
mmap2(0xb730d000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x10) = 0xb730d000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/i386-linux-gnu/libXpm.so.4", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0P%\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=67776, ...}) = 0
mmap2(NULL, 66460, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb72eb000
mmap2(0xb72fb000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x10) = 0xb72fb000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/i386-linux-gnu/libz.so.1", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\300\32\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=90192, ...}) = 0
mmap2(NULL, 92868, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb72d4000
mmap2(0xb72ea000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x15) = 0xb72ea000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/i386-linux-gnu/libexpat.so.1", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0@#\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=165192, ...}) = 0
mmap2(NULL, 167996, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb72aa000
mprotect(0xb72d0000, 4096, PROT_NONE)   = 0
mmap2(0xb72d1000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x26) = 0xb72d1000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/i386-linux-gnu/libxcb.so.1", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0P\221\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=136968, ...}) = 0
mmap2(NULL, 139728, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7287000
mmap2(0xb72a8000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x20) = 0xb72a8000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/i386-linux-gnu/i686/cmov/libdl.so.2", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0`\n\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=9844, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7286000
mmap2(NULL, 12408, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7282000
mmap2(0xb7284000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1) = 0xb7284000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/i386-linux-gnu/libSM.so.6", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0 \26\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=28320, ...}) = 0
mmap2(NULL, 31120, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb727a000
mmap2(0xb7281000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x6) = 0xb7281000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/i386-linux-gnu/libXau.so.6", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0`\n\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=8592, ...}) = 0
mmap2(NULL, 11384, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7277000
mmap2(0xb7279000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1) = 0xb7279000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/usr/lib/i386-linux-gnu/libXdmcp.so.6", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0P\17\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=19364, ...}) = 0
mmap2(NULL, 22144, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7271000
mmap2(0xb7276000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x4) = 0xb7276000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/i386-linux-gnu/libuuid.so.1", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0@\22\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=17992, ...}) = 0
mmap2(NULL, 20716, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb726b000
mmap2(0xb726f000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x3) = 0xb726f000
close(3)                                = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb726a000
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7269000
set_thread_area({entry_number:-1 -> 6, base_addr:0xb7269700, limit:1048575, seg_32bit:1, contents:0, read_exec_only:0, limit_in_pages:1, seg_not_present:0, useable:1}) = 0
mprotect(0xb726f000, 4096, PROT_READ)   = 0
mprotect(0xb7284000, 4096, PROT_READ)   = 0
mprotect(0xb72a8000, 4096, PROT_READ)   = 0
mprotect(0xb72d1000, 8192, PROT_READ)   = 0
mprotect(0xb73b0000, 16384, PROT_READ)  = 0
mprotect(0xb7427000, 4096, PROT_READ)   = 0
mprotect(0xb75b1000, 4096, PROT_READ)   = 0
mprotect(0xb770a000, 8192, PROT_READ)   = 0
mprotect(0xb772d000, 8192, PROT_READ)   = 0
mprotect(0x80a9000, 4096, PROT_READ)    = 0
mprotect(0xb77db000, 4096, PROT_READ)   = 0
munmap(0xb77b2000, 42995)               = 0
geteuid32()                             = 0
getegid32()                             = 0
getuid32()                              = 0
getgid32()                              = 0
setuid32(0)                             = 0
brk(0)                                  = 0x9e50000
brk(0x9e71000)                          = 0x9e71000
ioctl(0, SNDCTL_TMR_TIMEBASE or TCGETS, {B38400 opost isig icanon echo ...}) = 0
open("/proc/meminfo", 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) = 0xb77bc000
read(3, "MemTotal:        2039468 kB\nMemF"..., 1024) = 1024
close(3)                                = 0
munmap(0xb77bc000, 4096)                = 0
socket(PF_NETLINK, SOCK_RAW, 0)         = 3
bind(3, {sa_family=AF_NETLINK, pid=0, groups=00000000}, 12) = 0
getsockname(3, {sa_family=AF_NETLINK, pid=16008, groups=00000000}, [12]) = 0
time(NULL)                              = 1389599545
sendto(3, "\24\0\0\0\26\0\1\0039\233\323R\0\0\0\0\0\0\0\0", 20, 0, {sa_family=AF_NETLINK, pid=0, groups=00000000}, 12) = 20
recvmsg(3, {msg_name(12)={sa_family=AF_NETLINK, pid=0, groups=00000000}, msg_iov(1)=[{"0\0\0\0\24\0\2\0009\233\323R\210>\0\0\2\10\200\376\1\0\0\0\10\0\1\0\177\0\0\1"..., 4096}], msg_controllen=0, msg_flags=0}, 0) = 164
recvmsg(3, {msg_name(12)={sa_family=AF_NETLINK, pid=0, groups=00000000}, msg_iov(1)=[{"@\0\0\0\24\0\2\0009\233\323R\210>\0\0\n\200\200\376\1\0\0\0\24\0\1\0\0\0\0\0"..., 4096}], msg_controllen=0, msg_flags=0}, 0) = 320
recvmsg(3, {msg_name(12)={sa_family=AF_NETLINK, pid=0, groups=00000000}, msg_iov(1)=[{"\24\0\0\0\3\0\2\0009\233\323R\210>\0\0\0\0\0\0\1\0\0\0\24\0\1\0\0\0\0\0"..., 4096}], msg_controllen=0, msg_flags=0}, 0) = 20
close(3)                                = 0
socket(PF_FILE, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0) = 3
connect(3, {sa_family=AF_FILE, path="/var/run/nscd/socket"}, 110) = -1 ENOENT (No such file or directory)
close(3)                                = 0
socket(PF_FILE, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0) = 3
connect(3, {sa_family=AF_FILE, path="/var/run/nscd/socket"}, 110) = -1 ENOENT (No such file or directory)
close(3)                                = 0
open("/etc/nsswitch.conf", O_RDONLY)    = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=475, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb77bc000
read(3, "# /etc/nsswitch.conf\n#\n# Example"..., 4096) = 475
read(3, "", 4096)                       = 0
close(3)                                = 0
munmap(0xb77bc000, 4096)                = 0
open("/etc/host.conf", O_RDONLY)        = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=9, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb77bc000
read(3, "multi on\n", 4096)             = 9
read(3, "", 4096)                       = 0
close(3)                                = 0
munmap(0xb77bc000, 4096)                = 0
getpid()                                = 16008
open("/etc/resolv.conf", O_RDONLY)      = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=108, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb77bc000
read(3, "domain data.ee\nsearch data.ee li"..., 4096) = 108
read(3, "", 4096)                       = 0
close(3)                                = 0
munmap(0xb77bc000, 4096)                = 0
open("/etc/ld.so.cache", O_RDONLY)      = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=42995, ...}) = 0
mmap2(NULL, 42995, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb77b2000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/i386-linux-gnu/i686/cmov/libnss_files.so.2", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0P\32\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=42628, ...}) = 0
mmap2(NULL, 45768, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb725d000
mmap2(0xb7267000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x9) = 0xb7267000
close(3)                                = 0
mprotect(0xb7267000, 4096, PROT_READ)   = 0
munmap(0xb77b2000, 42995)               = 0
open("/etc/hosts", O_RDONLY|O_CLOEXEC)  = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=256, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb77bc000
read(3, "127.0.0.1\tlocalhost\n127.0.1.1\tTh"..., 4096) = 256
read(3, "", 4096)                       = 0
close(3)                                = 0
munmap(0xb77bc000, 4096)                = 0
socket(PF_INET, SOCK_STREAM|SOCK_CLOEXEC, IPPROTO_TCP) = 3
setsockopt(3, SOL_TCP, TCP_NODELAY, [1], 4) = 0
setsockopt(3, SOL_SOCKET, SO_KEEPALIVE, [1], 4) = 0
connect(3, {sa_family=AF_INET, sin_port=htons(6011), sin_addr=inet_addr("127.0.0.1")}, 16) = -1 ETIMEDOUT (Connection timed out)
close(3)                                = 0
open("/usr/lib/i386-linux-gnu/X11/XtErrorDB", O_RDONLY) = -1 ENOENT (No such file or directory)
getuid32()                              = 0
geteuid32()                             = 0
getuid32()                              = 0
write(2, "Warning: This program is an suid"..., 302Warning: This program is an suid-root program or is being run by the root user.
The full text of the error or warning message cannot be safely formatted
in this environment. You may get a more descriptive message by running the
program as a non-root user or by removing the suid bit on the executable.
) = 302
write(2, "xterm: ", 7xterm: )                  = 7
write(2, "Xt error: Can't open display: %s"..., 33Xt error: Can't open display: %s
) = 33
exit_group(1)                           = ?
# 

strace xterm hangs for 60 seconds after printing the line below:

connect(3, {sa_family=AF_INET, sin_port=htons(6011), sin_addr=inet_addr("127.0.0.1")}, 16

EDIT: after allowing connections from 127.0.0.0/8 to 127.0.0.0/8, I was able to pass the connect system call and now the issue seems to be an invalid MIT-MAGIC-COOKIE-1 key:

connect(3, {sa_family=AF_INET, sin_port=htons(6010), sin_addr=inet_addr("127.0.0.1")}, 16) = 0
getpeername(3, {sa_family=AF_INET, sin_port=htons(6010), sin_addr=inet_addr("127.0.0.1")}, [16]) = 0
uname({sys="Linux", node="ThinkCentreA58", ...}) = 0
access("/root/.Xauthority", R_OK)       = 0
open("/root/.Xauthority", O_RDONLY)     = 4
fstat64(4, {st_mode=S_IFREG|0600, st_size=522, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7726000
read(4, "\0\0\0\4\177\0\0\1\0\0041000\0\22MIT-MAGIC-COOKIE"..., 4096) = 522
read(4, "", 4096)                       = 0
close(4)                                = 0
munmap(0xb7726000, 4096)                = 0
getsockname(3, {sa_family=AF_INET, sin_port=htons(37220), sin_addr=inet_addr("127.0.0.1")}, [16]) = 0
fcntl64(3, F_GETFL)                     = 0x2 (flags O_RDWR)
fcntl64(3, F_SETFL, O_RDWR|O_NONBLOCK)  = 0
fcntl64(3, F_SETFD, FD_CLOEXEC)         = 0
poll([{fd=3, events=POLLIN|POLLOUT}], 1, -1) = 1 ([{fd=3, revents=POLLOUT}])
writev(3, [{"l\0\v\0\0\0\22\0\20\0\0\0", 12}, {"", 0}, {"MIT-MAGIC-COOKIE-1", 18}, {"\0\0", 2}, {"I%f9\331-f\f\235i\321\354:a~\341", 16}, {"", 0}], 6) = 48
recv(3, 0x94b0ec8, 8, 0)                = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=3, events=POLLIN}], 1, -1)    = 1 ([{fd=3, revents=POLLIN}])
recv(3, "\0\36\v\0\0\0\10\0", 8, 0)     = 8
recv(3, "Invalid MIT-MAGIC-COOKIE-1 key\0\0", 32, 0) = 32
write(2, "Invalid MIT-MAGIC-COOKIE-1 key", 30Invalid MIT-MAGIC-COOKIE-1 key) = 30
shutdown(3, 2 /* send and receive */)   = 0
close(3)                                = 0
open("/usr/lib/i386-linux-gnu/X11/XtErrorDB", O_RDONLY) = -1 ENOENT (No such file or directory)
getuid32()                              = 0
geteuid32()                             = 0
getuid32()                              = 0
write(2, "Warning: This program is an suid"..., 302Warning: This program is an suid-root program or is being run by the root user.
The full text of the error or warning message cannot be safely formatted
in this environment. You may get a more descriptive message by running the
program as a non-root user or by removing the suid bit on the executable.
) = 302
write(2, "xterm: ", 7xterm: )                  = 7
write(2, "Xt error: Can't open display: %s"..., 33Xt error: Can't open display: %s
) = 33
exit_group(1)                           = ?
# 

If any additional information is needed, please ask! Any ideas how to proceed with troubleshooting?

share|improve this question
    
This problem happens with any x program, even say xterm? –  Faheem Mitha Jan 10 at 9:00
1  
The # suggests you are logging in as root. If that is true, why? –  Faheem Mitha Jan 10 at 9:36
5  
Sometimes root is treated differently than other users. If possible, test with a normal user. In any case, doing things as root if you don't have to is generally a bad idea. –  Faheem Mitha Jan 10 at 11:47
3  
Also try using ssh -Y instead of ssh -X, that might help you get around authentication issues. –  terdon Jan 10 at 12:18
1  
@FaheemMitha I created a non-root user to a machine where SSH server is running and logged in to SSH server with this non-root user, but unfortunately this did not change anything. @terdon I tried with ssh -Y, but this did not help. I still receive the cannot open display error-message. –  Martin Jan 10 at 15:45

1 Answer 1

This is the very basic way of how it should work:

On the client / local machine (Xorg installed on client) try this:

$ xhost +
access control disabled, clients can connect from any host

Later try:

$ ssh -AY user@host xterm

or

$ ssh -AX user@host xterm

With non standard clients xhost may be needed.

check 9.3.5.6. Nonstandard X clients

share|improve this answer
    
As far as I know, xhost ACL is not even checked if X forwarding is done over SSH. –  Martin Jan 15 at 10:20
    
You are right, but for some reasons sometimes doesn't work as expected. you can also try this: - X11Forwarding yes X11DisplayOffset 10 X11UseLocalhost yes more on: X-Forwarding –  nbari Jan 15 at 10:27

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.