[Bug 300151] Re: ssh slow during logon, when ENTERING INTERACTIVE SESSION

Quinn Plattel qiet72 at gmail.com
Thu Feb 14 09:21:05 UTC 2013


Restart the dbus service on the ssh server "sudo restart dbus" - that should help.
If not, try adding "UseDNS=no" to your ssh server's sshd_config file and restart the service "sudo restart ssh"
If the UseDNS trick works, check your dns server setup.

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https://bugs.launchpad.net/bugs/300151

Title:
  ssh slow during logon, when ENTERING INTERACTIVE SESSION

Status in ConsoleKit:
  Fix Released
Status in Portable OpenSSH:
  Fix Released
Status in “openssh” package in Ubuntu:
  Fix Released

Bug description:
  I am using a Ubuntu Intrepid 32 bit server with all latest patches.

  Logging on via ssh (USING KEYS) is incredibly, painfully slow.

  I have done some investigation.

  1. Slowness is mild after a reboot and, as time goes on, it becomes
  progressively slower and sloowweerr and ssslllooowwweeerrrr.

  2. If I run ssh -v, then I can see that the ssh process is stuck for
  many seconds after saying "entering interactive session".

  3. This even happens if I do, from that server, a command "ssh
  localhost".

  4. Disabling GSSAPI authentication, as well as saying "UseDNS no", in
  sshd_config, does not help.

  5. A similar problems applies to use of "su" and can be more easily
  debugged. If, as root, I say "su - <username> date", it is also
  incredibly slow. If I debug that with

    strace -o q -f su - <myuserid> date

  then I see that su tries to connect to UNIX socket
  /var/run/dbus/system_bus_socket, and then it is stuck doing poll(),
  which remains <unfinished>. Not sure if it is related, but it could
  be.

  munmap(0x7f21ab91a000, 2970)            = 0
  close(4)                                = 0
  socket(PF_FILE, SOCK_STREAM, 0)         = 4
  connect(4, {sa_family=AF_FILE, path="/var/run/dbus/system_bus_socket"}, 33) = 0
  fcntl(4, F_GETFL)                       = 0x2 (flags O_RDWR)
  fcntl(4, F_SETFL, O_RDWR|O_NONBLOCK)    = 0
  fcntl(4, F_GETFD)                       = 0
  fcntl(4, F_SETFD, FD_CLOEXEC)           = 0
  geteuid()                               = 0
  poll([{fd=4, events=POLLOUT, revents=POLLOUT}], 1, 0) = 1
  write(4, "\0", 1)                       = 1
  write(4, "AUTH EXTERNAL 30\r\n", 18)    = 18
  poll([{fd=4, events=POLLIN, revents=POLLIN}], 1, -1) = 1
  read(4, "OK 951631a86cc350048c747bce491f8"..., 2048) = 37
  poll([{fd=4, events=POLLOUT, revents=POLLOUT}], 1, -1) = 1
  write(4, "BEGIN\r\n", 7)                = 7
  poll([{fd=4, events=POLLIN|POLLOUT, revents=POLLOUT}], 1, -1) = 1
  writev(4, [{"l\1\0\1\0\0\0\0\1\0\0\0n\0\0\0\1\1o\0\25\0\0\0/org/fre"..., 128}, {"", 0}], 2) = 128
  gettimeofday({1227143564, 211248}, NULL) = 0
  poll([{fd=4, events=POLLIN, revents=POLLIN}], 1, 25000) = 1
  read(4, "l\2\1\1\r\0\0\0\1\0\0\0E\0\0\0\6\1s\0\10\0\0\0:1.28259"..., 2048) = 282
  read(4, 0x24686e0, 2048)                = -1 EAGAIN (Resource temporarily unavailable)
  writev(4, [{"l\1\0\1\304\0\0\0\2\0\0\0\273\0\0\0\1\1o\0#\0\0\0/org/"..., 208}, {"\274\0\0\0\0\0\0\0\t\0\0\0unix-user\0\1i\0\0\0\0\350\3"..., 196}], 2) = 404
  gettimeofday({1227143564, 213048}, NULL) = 0
  poll(

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