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

[Narendra Prasad Madanapalli]

Thanks Eric for your response.

I am running TFTP as normal daemon but not xinetd daemon.

I noticed 1024 file descriptors are still opened even after all my
deployments (150+) are complete. In ideal case, FD for corresponding
request should be closed once the request is serviced.

Here again I am pasting the various log messages and limits in my system:

/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


> 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