From f3805e2166e2ab54cd9a6e8b7c536e6f20a61dff Mon Sep 17 00:00:00 2001 From: "Richard W.M. Jones" Date: Wed, 8 Dec 2010 12:12:08 +0000 Subject: [PATCH] rescue: Add notes about networking. In particular the 'ping' command does not work because it is using QEMU user networking. --- rescue/virt-rescue.pod | 38 +++++++++++++++++++++++++++++++++++++- 1 file changed, 37 insertions(+), 1 deletion(-) 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. =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 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 command. +You can make TCP connections from the shell using the magical +ChostnameE/EportE> syntax: + + exec 3<>/dev/tcp/redhat.com/80 + echo "GET /" >&3 + cat <&3 + +See L for more details. + +=back + =head1 ENVIRONMENT VARIABLES Several environment variables affect virt-rescue. See -- 1.8.3.1