Mercurial > dropbear
view debian/dropbear.postinst @ 1715:3974f087d9c0
Disallow leading lines before the ident for server (#102)
Per RFC4253 4.2 clients must be able to process other lines of data
before the version string, server behavior is not defined neither
with MUST/SHOULD nor with MAY.
If server process up to 50 lines too - it may cause too long hanging
session with invalid/evil client that consume host resources and
potentially may lead to DDoS on poor embedded boxes.
Let's require first line from client to be version string and fail
early if it's not - matches both RFC and real OpenSSH behavior.
author | Vladislav Grishenko <themiron@users.noreply.github.com> |
---|---|
date | Mon, 15 Jun 2020 18:22:18 +0500 |
parents | 7fc4ba3c1cbb |
children |
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#!/bin/sh set -e test "$1" = 'configure' || exit 0 if test ! -e /etc/dropbear/dropbear_rsa_host_key; then if test -f /etc/ssh/ssh_host_rsa_key; then echo "Converting existing OpenSSH RSA host key to Dropbear format." /usr/lib/dropbear/dropbearconvert openssh dropbear \ /etc/ssh/ssh_host_rsa_key /etc/dropbear/dropbear_rsa_host_key else echo "Generating Dropbear RSA key. Please wait." dropbearkey -t rsa -f /etc/dropbear/dropbear_rsa_host_key fi fi if test ! -e /etc/dropbear/dropbear_dss_host_key; then if test -f /etc/ssh/ssh_host_dsa_key; then echo "Converting existing OpenSSH RSA host key to Dropbear format." /usr/lib/dropbear/dropbearconvert openssh dropbear \ /etc/ssh/ssh_host_dsa_key /etc/dropbear/dropbear_dss_host_key else echo "Generating Dropbear DSS key. Please wait." dropbearkey -t dss -f /etc/dropbear/dropbear_dss_host_key fi fi if test ! -s /etc/default/dropbear; then # check whether OpenSSH seems to be installed. if test -x /usr/sbin/sshd; then cat <<EOT OpenSSH appears to be installed. Setting /etc/default/dropbear so that Dropbear will not start by default. Edit this file to change this behaviour. EOT cat >>/etc/default/dropbear <<EOT # disabled because OpenSSH is installed # change to NO_START=0 to enable Dropbear NO_START=1 EOT fi cat >>/etc/default/dropbear <<EOT # the TCP port that Dropbear listens on DROPBEAR_PORT=22 # any additional arguments for Dropbear DROPBEAR_EXTRA_ARGS= # specify an optional banner file containing a message to be # sent to clients before they connect, such as "/etc/issue.net" DROPBEAR_BANNER="" # RSA hostkey file (default: /etc/dropbear/dropbear_rsa_host_key) #DROPBEAR_RSAKEY="/etc/dropbear/dropbear_rsa_host_key" # DSS hostkey file (default: /etc/dropbear/dropbear_dss_host_key) #DROPBEAR_DSSKEY="/etc/dropbear/dropbear_dss_host_key" # Receive window size - this is a tradeoff between memory and # network performance DROPBEAR_RECEIVE_WINDOW=65536 EOT fi if test -x /etc/init.d/dropbear; then update-rc.d dropbear defaults >/dev/null if test -x /usr/sbin/invoke-rc.d; then invoke-rc.d dropbear restart else /etc/init.d/dropbear restart fi fi if test -n "$2" && dpkg --compare-versions "$2" lt '0.50-4' && update-service --check dropbear 2>/dev/null; then update-service --remove /etc/dropbear 2>/dev/null || : sleep 6 rm -rf /var/run/dropbear /var/run/dropbear.log update-service --add /etc/dropbear || : fi