xrdp-sesman fails to start at bootup

[Nikolas Britton]

Ubuntu 18.04: xrdp fails to start because xrdp-sesman fails to start at bootup. It appears to fail because it tries to start before the network is fully up. This may be related to disabling IPv6. If I add "ExecStartPre=/bin/sleep 20" to /lib/systemd/system/xrdp-sesman.service the service will then start successfully at bootup, so it appears this is simply a systemd timing issue. I tried charging network.target to network-online.target but that didn't resolve the problem.

This is the error message I get:

cat /var/log/xrdp-sesman.log
[20180424-13:20:06] [DEBUG] libscp initialized
[20180424-13:20:07] [INFO ] starting xrdp-sesman with pid 2149
[20180424-13:20:07] [INFO ] IPv6 not supported, falling back to IPv4
[20180424-13:20:07] [INFO ] IPv6 not supported, falling back to IPv4
[20180424-13:20:07] [DEBUG] Testing if xrdp-sesman can listen on 127.0.0.1 port 3350.
[20180424-13:20:07] [INFO ] listening to port 3350 on 127.0.0.1
[20180424-13:20:07] [ERROR] bind_loopback(5, 3350) failed; IPv6 ::1 (errno=97), IPv4 127.0.0.1 (errno=98) and IPv6 ::FFFF:127.0.0.1 (errno=97).
[20180424-13:20:07] [ERROR] Failed to start xrdp-sesman daemon, possibly address already in use.
[20180424-13:20:07] [INFO ] shutting down sesman 1
[20180424-13:20:07] [DEBUG] Closed socket 7 (AF_INET 127.0.0.1:3350)

Workaround:
Add "ExecStartPre=/bin/sleep 20" to the [Service] section of /lib/systemd/system/xrdp-sesman.service

The script below will setup my environment:
#!/bin/bash

### Install packages;
apt update;
apt upgrade -y;
apt install -y qemu-kvm libvirt-bin virtinst bridge-utils cpu-checker virt-manager xrdp xfce4 firefox xfce4-terminal nmap iotop;

### Disable IPv6 due to bugs... ####
sed -i 's/GRUB_CMDLINE_LINUX_DEFAULT=""/GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1"/' /etc/default/grub;

### Setup Network Dummy Interfaces ###
printf "[NetDev]\nName=dummy1\nKind=dummy\n" > /etc/systemd/network/dummy1.netdev;
printf "[NetDev]\nName=dummy2\nKind=dummy\n" > /etc/systemd/network/dummy2.netdev;
systemctl restart systemd-networkd.service;

### Netplan configuration ###
cat << 'EOF' > /etc/netplan/01-netcfg.yaml
# This file describes the network interfaces available on your system
# For more information, see netplan(5).
network:
  version: 2
  renderer: networkd

  ethernets:
    eno3: {}
    eno4: {}
    dummy1: {}
    dummy2: {}

  vlans:
    vbridge2-vlan10:
      id: 10
      link: vbridge2
      addresses: [10.11.1.2/24]
    vbridge2-vlan20:
      id: 20
      link: vbridge2
      addresses: [10.11.2.2/24]

  bonds:
    bond1:
      interfaces: [eno3, eno4]

  bridges:
    lab:
      interfaces: [bond1]
      addresses: [10.10.2.2/16]
      gateway4: 10.10.0.1
      nameservers:
        addresses: [8.8.8.8, 1.1.1.1]
    vbridge1:
      interfaces: [dummy1]
      addresses: [10.11.0.2/24]
    vbridge2:
      interfaces: [dummy2]
EOF
netplan apply;

### Enable nested virtualization ###
echo "options kvm-intel nested=y" >> /etc/modprobe.d/kvm.conf;

### Enable XRDP server ###
ufw allow 3389/tcp;
echo "xfce4-session" > /root/.xession;
echo "xfce4-session" > /home/nbritton/.xession;
echo "xfce4-session" >> /etc/xrdp/startwm.sh;
sed -i '/\/etc\/X11\/Xsession/ s/^/#/' /etc/xrdp/startwm.sh;
systemctl restart xrdp;
### End ###

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: xrdp 0.9.5-2 [modified: lib/systemd/system/xrdp-sesman.service]
ProcVersionSignature: Ubuntu 4.15.0-19.20-generic 4.15.17
Uname: Linux 4.15.0-19-generic x86_64
ApportVersion: 2.20.9-0ubuntu6
Architecture: amd64
Date: Tue Apr 24 13:56:50 2018
InstallationDate: Installed on 2018-04-24 (0 days ago)
InstallationMedia: Ubuntu-Server 18.04 LTS "Bionic Beaver" - Release amd64 (20180424.1)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: xrdp
UpgradeStatus: No upgrade log present (probably fresh install)
mtime.conffile..etc.xrdp.startwm.sh: 2018-04-24T12:58:12.608318

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[João Pedro Seara (jpseara)]

Noticed a similar issue today. With the difference that in my case, sesman would never come up. Found out that I was hitting [1]. Had to use workaround from [2].

Complete workaround was:

Fix was:

1. sudo bash -c 'export SYSTEMD_EDITOR="/usr/bin/vi" && systemctl edit xrdp-sesman.service'

2. sudo systemctl edit xrdp-sesman

[Service]
Type=simple
ExecStartPre=/bin/sleep 20

Save the file.

3. sudo vi /etc/default/xrdp

SESMAN_OPTIONS="-n"

4. sudo systemctl stop xrdp-sesman xrdp

5. sudo systemctl start xrdp-sesman xrdp

[1] https://github.com/neutrinolabs/xrdp/issues/1652
[2] https://github.com/neutrinolabs/xrdp/issues/1652#issuecomment-675387354