Hello !
Like Edmund EVANS reported openssh-2.1.1p4 won't fork to background when
using protocol 2.
I managed to hack a little patch that might work ...
What is the -N command line option supposed to do ? I gather it should work
only with protocol2 and without any command to run on the server (and with
some port forwardings ??)
Anyway in the patch I put some code to check that -N is used with port
forwards (and if used -f user doesn't have enter command). (If my
assumptions
about what -N is supposed to do are way off just rip out the unnecessary code
from the patch).
Also there seems to be a incompatibility issue with commercial ssh-2.2.0
and openssh when openssh client uses -N. If I press enter on the openssh
client then the commercial server sends "Window overflow received channel
data." and disconnects. This doesn't happen when both the client and
server
are openssh.
Cheers,
-Jarno
PS. I haven't done much testing with the patch so it'll propably break
something.
It works now for 'ssh -f -n -N -L5000:server:110 server' and
fetchmail.
Patch:
diff -u -r openssh-2.1.1p4/ssh.c openssh-2.1.1p4-ruined/ssh.c
--- openssh-2.1.1p4/ssh.c Sat Jul 15 07:14:17 2000
+++ openssh-2.1.1p4-ruined/ssh.c Fri Aug 4 20:54:10 2000
@@ -460,10 +460,6 @@
}
}
- /* Cannot fork to background if no command. */
- if (fork_after_authentication_flag && buffer_len(&command) == 0)
- fatal("Cannot fork into background without a command to execute.");
-
/* Allocate a tty by default if no command specified. */
if (buffer_len(&command) == 0)
tty_flag = 1;
@@ -511,6 +507,29 @@
/* reinit */
log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0);
+ /* -N option only makes sense with protocol 2. It doesn't make sense
+ without port forwarding ??????
+ */
+ if ( options.num_local_forwards == 0 && options.num_remote_forwards ==
0 &&
+ no_shell_flag ) {
+ fprintf(stderr, "-N makes sense only with port forwardings\n");
+ usage();
+ /* NOT REACHED */
+ }
+ if ((options.protocol & SSH_PROTO_2) && no_shell_flag &&
+ buffer_len(&command) > 0) {
+ fprintf(stderr,"-N option works only with protocol version 2 and w/out a
command\n");
+ usage();
+ /* NOT REACHED */
+ }
+
+ /* Cannot fork to background if no command.
+ Command not needed for protocol 2 & -N
+ */
+ if ((options.protocol & SSH_PROTO_1) && !(options.protocol &
SSH_PROTO_2) &&
+ fork_after_authentication_flag && buffer_len(&command) == 0)
+ fatal("Cannot fork into background without a command to
execute.");
+
/* check if RSA support exists */
if ((options.protocol & SSH_PROTO_1) &&
rsa_alive() == 0) {
@@ -979,6 +998,12 @@
channel_open(id);
channel_register_callback(id, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, client_init,
(void *)0);
+
+ /* Jarno: hack to get -f working with protocol 2 */
+ if (fork_after_authentication_flag) {
+ if (daemon(1, 1) < 0)
+ fatal("daemon() failed: %.200s", strerror(errno));
+ }
return client_loop(tty_flag, tty_flag ? options.escape_char : -1);
}
--
Jarno Huuskonen - System Administrator | Jarno.Huuskonen at uku.fi
University of Kuopio - Computer Center | Work: +358 17 162822
PL 1627, 70211 Kuopio, Finland | Mobile: +358 40 5388169
