Unexpected behaviours with TCL/Expect and Cisco - ios

Question

I'm trying to log into a Cisco switch and run a list of commands.
Using the following code, I'm able to log into the device, enable, and configure terminal:
# Connect to single host, enable, and configure
proc connect {host payload username password enablepassword} {
send_user "Connecting to: $host $payload $username $password $enablepassword\n"
spawn ssh -o "StrictHostKeyChecking no" -l $username $host
# # Pardon the rudeness; some switches are upper case, some are lower case
expect "assword:"
send "$password\r"
# Switch to enable mode
expect ">"
send "en\r"
expect "assword:"
send "$enablepassword\r"
expect "*#"
send -- "conf t\r"
expect "config*#"
}
However, using the following code, I get the output below. ($payload contains a file which has one IOS command per line)
proc drop_payload {payload} {
set f [open "$payload"]
set payload [split [read $f] "\n"]
close $f
foreach pld $payload {
send -- "$pld\r"
expect "config*#"
sleep 2
}
}
My expectation is that this loop will iterate over each line in the file, however, the Expect debug (from exp_internal 1) is as follows:
HOST-0001#
expect: does " \r\HOST-0001#" (spawn_id exp7) match glob pattern "*#"? yes
expect: set expect_out(0,string) " \r\nHOST-0001#"
expect: set expect_out(spawn_id) "exp7"
expect: set expect_out(buffer) " \r\nHOST-0001#"
send: sending "conf t\r" to { exp7 }
expect: does "" (spawn_id exp7) match glob pattern "config*#"? no
c
expect: does "c" (spawn_id exp7) match glob pattern "config*#"? no
o
expect: does "co" (spawn_id exp7) match glob pattern "config*#"? no
n
expect: does "con" (spawn_id exp7) match glob pattern "config*#"? no
f
expect: does "conf" (spawn_id exp7) match glob pattern "config*#"? no
expect: does "conf " (spawn_id exp7) match glob pattern "config*#"? no
t
expect: does "conf t" (spawn_id exp7) match glob pattern "config*#"? no
expect: does "conf t\r\n" (spawn_id exp7) match glob pattern "config*#"? no
Enter configuration commands, one per line. End with CNTL/Z.
HOST-0001(config)#
expect: does "conf t\r\nEnter configuration commands, one per line. End with CNTL/Z.\r\nHOST-0001(config)#" (spawn_id exp7) match glob pattern "config*#"? yes
expect: set expect_out(0,string) "configuration commands, one per line. End with CNTL/Z.\r\nHOST-0001(config)#"
expect: set expect_out(spawn_id) "exp7"
expect: set expect_out(buffer) "conf t\r\nEnter configuration commands, one per line. End with CNTL/Z.\r\nHOST-0001(config)#"
}end: sending "no logging 172.x.x.20\r" to { exp0 no logging 172.x.x.20
expect: does "" (spawn_id exp0) match glob pattern "config*#"? no
expect: timed out
}end: sending "no logging 172.x.x.210\r" to { exp0 no logging 172.x.x.210
expect: does "" (spawn_id exp0) match glob pattern "config*#"? no
expect: timed out
}end: sending "no logging 172.x.x.9\r" to { exp0 no logging 172.x.x.9
expect: does "" (spawn_id exp0) match glob pattern "config*#"? no
expect: timed out
}end: sending "no logging 172.x.x.210\r" to { exp0 no logging 172.x.x.210
expect: does "" (spawn_id exp0) match glob pattern "config*#"? no
expect: timed out
}end: sending "no logging 172.x.x.20\r" to { exp0 no logging 172.x.x.20
expect: does "" (spawn_id exp0) match glob pattern "config*#"? no
expect: timed out
}end: sending "logging 172.x.x.50\r" to { exp0 logging 172.x.x.50
expect: does "" (spawn_id exp0) match glob pattern "config*#"? no
expect: timed out
I'm confused as to why it's trying to expect "conf t" which is being sent to the host; not received.
I'm also confused as to why any of the commands end after conf t is applied don't hit the switch, and time out instead.

Answer 1

You can try sending the configurations with the spwan_id
spawn ssh -o "StrictHostKeyChecking no" -l $username $host
#After process creation the process id will be saved in
#standard expect variable'spawn_id'
#Copying it to variable 'id'
set id $spawn_id
Now the variable 'id' is holding the reference to the ssh process. We can very well use the send and expect with the spawn id.
#Now we are setting the spawn id to our ssh process to make sure
#we are sending the commands to right process
#You can pass this variable 'id' as arg in 'drop_payload'
set spawn_id $id
foreach pld $payload {
send -- "$pld\r"
expect "config*#"
sleep 2
}
Or the other way around is as follows,
foreach pld $payload {
#This way is useful, when u want to send and expect to multiple process
#simultaneously.
send -i $id "$pld\r"
expect -i $id "config*#"
sleep 2
}

Answer 2

I found that each function/procedure was outputting to a new spawn ID.
One method is to follow Dinesh's advice and explicitly define the spawn id.
My workaround was to simply stuff everything into a single output procedure.