[syslog-ng] Using usertty

Alexandre Santos alexandre.rosas.santos at gmail.com
Wed Oct 28 17:24:44 UTC 2020


Hi Gabor,

Thanks for your help, testing with echo "test" is working fine (check
bellow), but with usertty, I still have the same problem.

Furthermore, I tried strace and saw the following:


*[pid  2177] rt_sigaction(SIGALRM, {sa_handler=0x7fa889b23e10, sa_mask=[],
sa_flags=SA_RESTORER, sa_restorer=0x7fa889541840}, NULL, 8) = 0[pid  2177]
write(2</dev/pts/1<char 136:1>>, "[2020-10-28T17:15:36.178232] Posting
message to user terminal; user='thanos', line='/dev/ttyS0'\n", 96) = 96[pid
 2177] openat(AT_FDCWD, "/dev/ttyS0",
O_WRONLY|O_NOCTTY|O_APPEND|O_NONBLOCK) = -1 EACCES (Permission denied)*

Do you know why? I am launching syslog-ng as root. (full strace in
attachment)

Regards,
Alex



















*thanos at debian10st:~$ echo test >
/dev/ttyS0testroot at debian10st:/home/thanos# who am ithanos   pts/1
 2020-10-26 20:21 (10.0.2.2)root at debian10st:/home/thanos# echo "test1" >
/dev/pts/1test1root at debian10st:/home/thanos#thanos at debian10st:~$ who am
ithanos   pts/0        2020-10-26 20:21 (10.0.2.2)thanos at debian10st:~$ echo
"test0" > /dev/pts/0test0thanos at debian10st:~$root at debian10st:/home/thanos#
who am ithanos   pts/2        2020-10-26 20:26
(10.0.2.2)root at debian10st:/home/thanos# echo "test2" > /dev/pts/2test2*

On Wed, Oct 28, 2020 at 3:33 PM Gabor Nagy (gnagy) <
Gabor.Nagy at oneidentity.com> wrote:

> Thanks for the info!
>
> It looks good, messages should be seen on ssh and on serial console too.
> Can you try out if you can write in the /dev/ttyS0 file (and/or the ssh
> login console, in your example /dev/pts/1) with a simple "echo test"
> command and see if it appears on the console, please?
> ------------------------------
> *From:* syslog-ng <syslog-ng-bounces at lists.balabit.hu> on behalf of
> Alexandre Santos <alexandre.rosas.santos at gmail.com>
> *Sent:* Tuesday, October 27, 2020 10:20
> *To:* Syslog-ng users' and developers' mailing list <
> syslog-ng at lists.balabit.hu>
> *Subject:* Re: [syslog-ng] Using usertty
>
> CAUTION: This email originated from outside of the organization. Do not
> follow guidance, click links, or open attachments unless you recognize the
> sender and know the content is safe.
>
> Hi Gabor,
>
> I am running a Debian buster in a VBox guest.
>
> Can you check which terminals are the user 'thanos' logged in?
>
>
>
>
>
>
> *root at debian10st:/home/thanos# w thanos  09:15:47 up 22:00,  4 users,
>  load average: 0.00, 0.02, 0.00 USER     TTY      FROM             LOGIN@
> IDLE   JCPU   PCPU WHAT thanos   ttyS0    -                Mon20    8:27
> 0.05s  0.04s -bash thanos   pts/0    10.0.2.2         Mon20   12:54m  0.03s
>  0.03s -bash thanos   pts/1    10.0.2.2         Mon20   12:50m  0.12s
>  0.18s sshd: thanos [priv] thanos   pts/2    10.0.2.2         Mon20
>  1.00s  0.04s  0.20s sshd: thanos [priv]*
>
> Here are the serial configurations:
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> *root at debian10st:/home/thanos# stty -F /dev/ttyS0 -a speed 9600 baud; rows
> 24; columns 80; line = 0; intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof
> = ^D; eol = <undef>; eol2 = <undef>; swtch = <undef>; start = ^Q; stop =
> ^S; susp = ^Z; rprnt = ^R; werase = ^W; lnext = <undef>; discard = <undef>;
> min = 1; time = 0; -parenb -parodd -cmspar cs8 hupcl -cstopb cread clocal
> -crtscts -ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr
> -icrnl ixon ixoff -iuclc -ixany -imaxbel iutf8 opost -olcuc -ocrnl onlcr
> -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0 isig -icanon -iexten
> -echo echoe echok -echonl -noflsh -xcase -tostop -echoprt echoctl echoke
> -flusho -extproc root at debian10st:/home/thanos# stty -F /dev/pts/0 -a speed
> 38400 baud; rows 50; columns 184; line = 0; intr = ^C; quit = ^\; erase =
> ^H; kill = ^U; eof = ^D; eol = <undef>; eol2 = <undef>; swtch = <undef>;
> start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R; werase = ^W; lnext = <undef>;
> discard = <undef>; min = 1; time = 0; -parenb -parodd -cmspar cs8 -hupcl
> -cstopb cread -clocal -crtscts -ignbrk -brkint -ignpar -parmrk -inpck
> -istrip -inlcr -igncr -icrnl ixon -ixoff -iuclc ixany -imaxbel iutf8 opost
> -olcuc -ocrnl onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0
> isig -icanon iexten -echo echoe echok -echonl -noflsh -xcase -tostop
> -echoprt echoctl echoke -flusho -extproc *
>
>
>
>
>
>
>
>
>
> *root at debian10st:/home/thanos# stty -F /dev/pts/1 -a speed 38400 baud;
> rows 50; columns 184; line = 0; intr = ^C; quit = ^\; erase = ^H; kill =
> ^U; eof = ^D; eol = <undef>; eol2 = <undef>; swtch = <undef>; start = ^Q;
> stop = ^S; susp = ^Z; rprnt = ^R; werase = ^W; lnext = ^V; discard = ^O;
> min = 1; time = 0; -parenb -parodd -cmspar cs8 -hupcl -cstopb cread -clocal
> -crtscts -ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl
> ixon -ixoff -iuclc ixany -imaxbel iutf8 opost -olcuc -ocrnl onlcr -onocr
> -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0 isig icanon iexten echo
> echoe echok -echonl -noflsh -xcase -tostop -echoprt echoctl echoke -flusho
> -extproc *
>
>
>
>
>
>
>
>
>
> *root at debian10st:/home/thanos# stty -F /dev/pts/2 -a speed 38400 baud;
> rows 50; columns 184; line = 0; intr = ^C; quit = ^\; erase = ^H; kill =
> ^U; eof = ^D; eol = <undef>; eol2 = <undef>; swtch = <undef>; start = ^Q;
> stop = ^S; susp = ^Z; rprnt = ^R; werase = ^W; lnext = ^V; discard = ^O;
> min = 1; time = 0; -parenb -parodd -cmspar cs8 -hupcl -cstopb cread -clocal
> -crtscts -ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl
> ixon -ixoff -iuclc ixany -imaxbel iutf8 opost -olcuc -ocrnl onlcr -onocr
> -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0 isig icanon iexten echo
> echoe echok -echonl -noflsh -xcase -tostop -echoprt echoctl echoke -flusho
> -extproc *
>
> Thanks,
> Alex
>
> On Mon, Oct 26, 2020 at 10:59 AM Gabor Nagy (gnagy) <
> Gabor.Nagy at oneidentity.com> wrote:
>
> Hi Alex!
>
> I've checked your attachments and I see that the messages are sent to
> pseudo-terminals and the serial port too:
> [2020-10-23T16:40:20.647481] Posting message to user terminal;
> user='thanos', line='/dev/ttyS0'
> [2020-10-23T16:40:20.647518] Posting message to user terminal;
> user='thanos', line='/dev/pts/0'
> [2020-10-23T16:40:20.647530] Posting message to user terminal;
> user='thanos', line='/dev/pts/1'
> [2020-10-23T16:40:20.647541] Posting message to user terminal;
> user='thanos', line='/dev/pts/2'
>
> Can you check which terminals are the user 'thanos' logged in?
> E.g. use the following command on the command line:
> $w thanos
>
> If you don't see a tty with ssh login, that can explain it.
>
> About the serial port, maybe it's misconfigured.
> Syslog-ng uses simple open/write calls on the device files , e.g.
> /dev/ttyS0. Can you try out if you can write in the /dev/ttyS0 file with a
> simple "echo test" command, please?
> Can you tell us a bit more about your host and how did you set up the
> serial port?
>
> Regards,
> Gabor
> ------------------------------
> *From:* syslog-ng <syslog-ng-bounces at lists.balabit.hu> on behalf of
> Alexandre Santos <alexandre.rosas.santos at gmail.com>
> *Sent:* Friday, October 23, 2020 17:46
> *To:* Syslog-ng users' and developers' mailing list <
> syslog-ng at lists.balabit.hu>
> *Subject:* [syslog-ng] Using usertty
>
> CAUTION: This email originated from outside of the organization. Do not
> follow guidance, click links, or open attachments unless you recognize the
> sender and know the content is safe.
>
> Hi,
> I am trying to use usertty(*) to send log all messages with severity equal
> or higher than critical to every user logged.
>
> But I am not getting any messages in serial port or ssh.
>
> I am sending the configurations and the debug log in attachment.
>
> Can you help me to understand what is happening?
>
> Thanks in advance,
> Alex
>
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