telnet fail on a situation
Not sure if this can be a right forum for this question; let me know if there will be a better one.
The system is like this: - 2 processes: 'A' and 'B' - 'A' monitors 'B' - when the system starts cronjob starts 'A' and 'A' starts 'B' -- (1) - if 'B' dies 'A' re-starts 'B' -- (2) - 'B' performs a task which calls a expect script to do 'telnet' with other devices (telnet servers) - 'A' uses 'system()' to start 'B' Symtoms: - for (1), telnet works fine - for (2), telnet doesn't work fine <<<<< issue - (wireshark analysis) telnet fails b/c 'B' doesn't respond to a device's first telnet data; it ACKs on TCP but no data after; so the expect script time-out - if run 'B' from shell (instead of from 'A'): no problem - if run expect from shell: no problem - ssh (instead of telnet): no problem - rebooting linux won't help - this only happens on certain machines (with same linux) Env: - CentOS release 5.2 on VMware (ESXi 4.1) - expect: 5.43.0 I have checked ENV and proc stats for (1) and (2) but haven't found a noticeable difference. Increasing ulimit and other resource won't help. 'A' & 'B' fd usage, for example, is not that big; ~20. Any insight? Thanks in advance, |
Did you use autoexpect to create the script?
My wild guess may be that you need to add in some waits/pause to telnet. |
Thanks for the input.
"waits/pause to telnet", do you mean timeout in expect? We use timeout in the script and I played with that value but it didn't help. I am using a script someone else created so not sure if he used the tool; I doubt it though. Goolged timeout options for telnet itself but it doesn't seem that telnet has that option. |
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