[syslinux] TFTPD: Cannot open /etc/hosts.{allow, deny}: Too many open files

[Lee Eric]

Hey mate,

you may need to have a look at /etc/xinetd.d/tftp and try to modify
cps parameter. Your problem may caused by too may connections at the
same time with tftp daemon. You can increase the first value to 200
and the second value you can set up to 1. That means max "200"
simultaneous connections to any one service. if 200 is reached, back
off for "1" sec.

Regards,

Eric

On Sun, Aug 21, 2011 at 7:38 PM, Narendra Prasad Madanapalli
<narendramind at gmail.com> wrote:
> Hi,
>
> I have been running TFTPD server for 3 weeks and performed about 100
> deployments. After that, TFTPD started throwing the follwing errotrs in
> /var/log/messages
>
> Aug 20 21:52:55 RTP-OSP-Server tftpd[7146]: warning: cannot open
> /etc/hosts.allow: Too many open files
> Aug 20 21:52:55 RTP-OSP-Server tftpd[7146]: warning: cannot open
> /etc/hosts.deny: Too many open files
> Aug 20 21:52:55 RTP-OSP-Server tftpd[7146]: connection refused from 0.0.0.0
> Aug 20 21:52:57 RTP-OSP-Server tftpd[7147]: warning: cannot open
> /etc/hosts.allow: Too many open files
> Aug 20 21:52:57 RTP-OSP-Server tftpd[7147]: warning: cannot open
> /etc/hosts.deny: Too many open files
> Aug 20 21:52:57 RTP-OSP-Server tftpd[7147]: connection refused from 0.0.0.0
>
> Here is the output of lsof -p 20782 -l
>
> COMMAND   PID     USER   FD   TYPE     DEVICE    SIZE     NODE NAME
> tftpd   20782        0  cwd    DIR      253,0    4096 13205505 /opt/tftpboot
> tftpd   20782        0  rtd    DIR      253,0    4096        2 /
> tftpd   20782        0  txt    REG      253,0   27984 32871493
> /opt/tftp/sbin/tftpd
> tftpd   20782        0  mem    REG      253,0  125736 20841853 /lib/
> ld-2.5.so
> tftpd   20782        0  mem    REG      253,0 1602128 20841854 /lib/
> libc-2.5.so
> tftpd   20782        0  mem    REG      253,0   32856 54860420
> /usr/lib/libwrap.so.0.7.6
> tftpd   20782        0  mem    REG      253,0  101404 20841866 /lib/
> libnsl-2.5.so
> tftpd   20782        0  mem    REG      253,0   46680 20840489 /lib/
> libnss_files-2.5.so
> tftpd   20782        0    0u   CHR        1,3             1574 /dev/null
> tftpd   20782        0    1u   CHR        1,3             1574 /dev/null
> tftpd   20782        0    2u   CHR        1,3             1574 /dev/null
> tftpd   20782        0    3u  unix 0xf73a2ac0          2943680 socket
> tftpd   20782        0    4u  IPv4    2943683              UDP *:tftp
> tftpd   20782        0    5u  sock        0,5          2945126 can't
> identify protocol
> tftpd   20782        0    6u  sock        0,5          2946157 can't
> identify protocol
> tftpd   20782        0    7u  sock        0,5          2947174 can't
> identify protocol
> tftpd   20782        0    8u  sock        0,5          2952758 can't
> identify protocol
> tftpd   20782        0    9u  sock        0,5          2953809 can't
> identify protocol
> tftpd   20782        0   10u  sock        0,5          2959221 can't
> identify protocol
> tftpd   20782        0   11u  sock        0,5          2965427 can't
> identify protocol
> tftpd   20782        0   12u  sock        0,5          2968500 can't
> identify protocol
> .......
> ......
> tftpd   20782        0 1019u  sock        0,5          4833123 can't
> identify protocol
> tftpd   20782        0 1020u  sock        0,5          4839162 can't
> identify protocol
> tftpd   20782        0 1021u  sock        0,5          4840216 can't
> identify protocol
> tftpd   20782        0 1022u  sock        0,5          4841243 can't
> identify protocol
> tftpd   20782        0 1023u  sock        0,5          4842249 can't
> identify protocol
>
>
> And the output of limits
>
> # cat /proc/sys/fs/file-max
> 754278
>
> # cat /proc/sys/fs/file-nr
> 2496    0       754278
>
> # ulimit -n
> 1024
>
>
> I am not sure why TFTPD is not closing all opened sockets.
>
> I noticed in the file tftp-hpa-5.0/tftpd/tftpd.c around line 906 it opens a
> socket and there is no corresponding close() statemnt for that.
>
>
>
> Any help on this would be highly appreciated?
>
>
> Thanks,
> Narendra.
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