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Description of problem:
The xvfb-run "-l" or "--listen-tcp" option does not work
Version-Release number of selected component (if applicable):
xorg-x11-server-Xvfb-1.20.11-9.el8.x86_64
How reproducible:
Always
Steps to Reproduce:
1. Install xorg-x11-server-Xvfb and xterm
2. Log in via GDM
3. Open a gnome-terminal window and run this test command:
$ xvfb-run -d -l -s "-ac" bash -c "export DISPLAY=localhost\$DISPLAY; xterm -e 'echo hello;sleep 1';"
Actual results:
xterm: Xt error: Can't open display: localhost:2
Expected results:
xterm should run using a Xvfb server that listens at localhost, port 6002.
Additional info:
As a workaround, it's possible to pass "-isten tcp" to Xvfb:
$ xvfb-run -d -l -s "-ac -listen tcp" bash -c "export DISPLAY=localhost\$DISPLAY; xterm -e 'echo hello;sleep 1';"
The cause of the problem is that when we pass "-l" or "--listen-tcp" to
xvfb-run it sets the LISTENTCP variable to empty:
LISTENTCP="-nolisten tcp"
...
while :; do
case "$1" in
-a|--auto-servernum) SERVERNUM=$(find_free_servernum) ;;
-d|--auto-display) AUTO_DISPLAY=1 ;;
-e|--error-file) ERRORFILE="$2"; shift ;;
-f|--auth-file) AUTHFILE="$2"; shift ;;
-h|--help) SHOWHELP="yes" ;;
-n|--server-num) SERVERNUM="$2"; shift ;;
-l|--listen-tcp) LISTENTCP="" ;;
-p|--xauth-protocol) XAUTHPROTO="$2"; shift ;;
-s|--server-args) XVFBARGS="$2"; shift ;;
-w|--wait) STARTWAIT="$2"; shift ;;
--) shift; break ;;
*) error "internal error; getopt permitted \"$1\" unexpectedly"
exit 6
;;
esac
shift
done
Starting on RHEL 8, however the X server (including Xvfb) does not listen on a
TCP port by default, as it did up to RHEL 7. So it would be necessary to set
LISTENTCP to "-listen tcp".
The problem happens on RHEL 9 too, for the same reason.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory (Moderate: xorg-x11-server security and bug fix update), and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHSA-2023:2806
Comment 12Red Hat Bugzilla
2023-09-19 04:33:33 UTC
The needinfo request[s] on this closed bug have been removed as they have been unresolved for 120 days
Description of problem: The xvfb-run "-l" or "--listen-tcp" option does not work Version-Release number of selected component (if applicable): xorg-x11-server-Xvfb-1.20.11-9.el8.x86_64 How reproducible: Always Steps to Reproduce: 1. Install xorg-x11-server-Xvfb and xterm 2. Log in via GDM 3. Open a gnome-terminal window and run this test command: $ xvfb-run -d -l -s "-ac" bash -c "export DISPLAY=localhost\$DISPLAY; xterm -e 'echo hello;sleep 1';" Actual results: xterm: Xt error: Can't open display: localhost:2 Expected results: xterm should run using a Xvfb server that listens at localhost, port 6002. Additional info: As a workaround, it's possible to pass "-isten tcp" to Xvfb: $ xvfb-run -d -l -s "-ac -listen tcp" bash -c "export DISPLAY=localhost\$DISPLAY; xterm -e 'echo hello;sleep 1';" The cause of the problem is that when we pass "-l" or "--listen-tcp" to xvfb-run it sets the LISTENTCP variable to empty: LISTENTCP="-nolisten tcp" ... while :; do case "$1" in -a|--auto-servernum) SERVERNUM=$(find_free_servernum) ;; -d|--auto-display) AUTO_DISPLAY=1 ;; -e|--error-file) ERRORFILE="$2"; shift ;; -f|--auth-file) AUTHFILE="$2"; shift ;; -h|--help) SHOWHELP="yes" ;; -n|--server-num) SERVERNUM="$2"; shift ;; -l|--listen-tcp) LISTENTCP="" ;; -p|--xauth-protocol) XAUTHPROTO="$2"; shift ;; -s|--server-args) XVFBARGS="$2"; shift ;; -w|--wait) STARTWAIT="$2"; shift ;; --) shift; break ;; *) error "internal error; getopt permitted \"$1\" unexpectedly" exit 6 ;; esac shift done Starting on RHEL 8, however the X server (including Xvfb) does not listen on a TCP port by default, as it did up to RHEL 7. So it would be necessary to set LISTENTCP to "-listen tcp". The problem happens on RHEL 9 too, for the same reason.