File 0018-rescue-Add-notes-about-networking.patch of Package libguestfs
From f00ed685207d0f8807de0ec90c86d8f60aec217f Mon Sep 17 00:00:00 2001 From: Richard W.M. Jones <rjones@redhat.com> Date: Wed, 8 Dec 2010 12:12:08 +0000 Subject: [PATCH 18/72] rescue: Add notes about networking. In particular the 'ping' command does not work because it is using QEMU user networking. (cherry picked from commit f3805e2166e2ab54cd9a6e8b7c536e6f20a61dff) --- rescue/virt-rescue.pod | 38 +++++++++++++++++++++++++++++++++++++- 1 files changed, 37 insertions(+), 1 deletions(-) diff --git a/rescue/virt-rescue.pod b/rescue/virt-rescue.pod index 0c24471..415bcda 100755 --- a/rescue/virt-rescue.pod +++ b/rescue/virt-rescue.pod @@ -155,7 +155,7 @@ parameter is specified in megabytes. =item B<--network> -Enable QEMU user networking in the guest. +Enable QEMU user networking in the guest. See L</NETWORK>. =item B<-r> @@ -206,6 +206,42 @@ name as a guest. For compatibility the old style is still supported. +=head1 NETWORK + +Adding the I<--network> option enables QEMU user networking +in the rescue appliance. There are some differences between +user networking and ordinary networking: + +=over 4 + +=item ping does not work + +Because the ICMP ECHO_REQUEST protocol generally requires root in +order to send the ping packets, and because virt-rescue must be able +to run as non-root, QEMU user networking is not able to emulate the +L<ping(8)> command. The ping command will appear to resolve addresses +but will not be able to send or receive any packets. This does not +mean that the network is not working. + +=item cannot receive connections + +QEMU user networking cannot receive incoming connections. + +=item making TCP connections + +The virt-rescue appliance needs to be small and so does not include +many network tools. In particular there is no L<telnet(1)> command. +You can make TCP connections from the shell using the magical +C</dev/tcp/E<lt>hostnameE<gt>/E<lt>portE<gt>> syntax: + + exec 3<>/dev/tcp/redhat.com/80 + echo "GET /" >&3 + cat <&3 + +See L<bash(1)> for more details. + +=back + =head1 ENVIRONMENT VARIABLES Several environment variables affect virt-rescue. See -- 1.7.1
