Docker ubuntu 20.04 container OSError: [Errno 18] Invalid cross-device link: '/etc/hosts' -> '/etc/hosts.sbak'

[bgreenacre]

I'm trying to build a docker image with ubuntu 20.04 as a base and I always get the Errno 18 when I build it. I've searched here and found a similar issue on #398 which lead me to https://stackoverflow.com/questions/60529231/invoking-iptables-results-in-operation-not-supported-in-docker. So I tried the suggested update-alternatives --set iptables /usr/sbin/iptables-legacy in my Dockerfile but there's no change. I still get the same error.

Here's some verbose output of sshuttle:
I've removed some of it to remove alot of the hosts I end up getting when connected

Starting sshuttle proxy.
firewall manager: Starting firewall with Python version 3.8.2
firewall manager: ready method name nat.
IPv6 enabled: None
UDP enabled: False
DNS enabled: True
User enabled: False
Binding redirector: 12300
TCP redirector listening on ('127.0.0.1', 12300).
TCP redirector listening with <socket.socket fd=5, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=0, laddr=('127.0.0.1', 12300)>.
Binding DNS: 12300 12299
DNS listening on ('127.0.0.1', 12299).
DNS listening with <socket.socket fd=7, family=AddressFamily.AF_INET, type=SocketKind.SOCK_DGRAM, proto=0, laddr=('127.0.0.1', 12299)>.
Starting client with Python version 3.8.2
c : connecting to server...
c : executing: ['/usr/bin/ssh', '-oStrictHostKeyChecking=no', '<user>@192.168.1.129', '--', '/bin/sh -c \'P=python3; $P -V 2>/dev/null || P=python; exec "$P" -c \'"\'"\'import sys, os; verbosity=3; sys.stdin = os.fdopen(0, "rb"); exec(compile(sys.stdin.read(1490), "assembler.py", "exec"))\'"\'"\'\'']
c :  > channel=0 cmd=PING len=7 (fullness=0)
Warning: Permanently added '192.168.1.129' (ECDSA) to the list of known hosts.
server: assembling 'sshuttle' (88 bytes)
server: assembling 'sshuttle.cmdline_options' (60 bytes)
server: assembling 'sshuttle.helpers' (892 bytes)
server: assembling 'sshuttle.ssnet' (5789 bytes)
server: assembling 'sshuttle.hostwatch' (2466 bytes)
server: assembling 'sshuttle.server' (3929 bytes)
Starting server with Python version 3.8.2
 s: latency control setting = True
 s:  > channel=0 cmd=PING len=7 (fullness=0)
c : Connected.
c : seed_hosts: []
c :  > channel=0 cmd=HOST_REQ len=0 (fullness=7)
c : Waiting: 3 r=[5, 7, 9] w=[9] x=[] (fullness=7/0)
 s: auto-nets:True
c :   Ready: 3 r=[] w=[9] x=[]
c : mux wrote: 15/15
c : Waiting: 3 r=[5, 7, 9] w=[9] x=[] (fullness=7/0)
c :   Ready: 3 r=[] w=[9] x=[]
c : mux wrote: 8/8
c : Waiting: 3 r=[5, 7, 9] w=[] x=[] (fullness=7/0)
 s: available routes:
 s:   2/169.254.0.0/16
 s:   2/169.254.169.254/32
 s:   2/192.168.1.0/24
 s:   2/192.168.1.1/32
 s:   2/192.168.1.1/32
 s:   2/192.168.1.111/32
 s:   2/192.168.1.129/32
 s:   2/192.168.1.144/32
 s:   2/224.0.0.0/4
 s:   2/224.0.0.251/32
 s:   2/255.255.255.255/32
 s:  > channel=0 cmd=ROUTES len=198 (fullness=7)
 s: Waiting: 1 r=[0] w=[1] x=[] (fullness=205/0)
 s:   Ready: 1 r=[0] w=[1] x=[]
 s: <  channel=0 cmd=PING len=7
 s:  > channel=0 cmd=PONG len=7 (fullness=205)
 s: <  channel=0 cmd=HOST_REQ len=0
c :   Ready: 3 r=[9] w=[] x=[]
c : <  channel=0 cmd=PING len=7
c :  > channel=0 cmd=PONG len=7 (fullness=7)
c : mux wrote: 15/15
c : Waiting: 3 r=[5, 7, 9] w=[] x=[] (fullness=14/0)
 s: mux wrote: 15/15
 s: mux wrote: 206/206
c :   Ready: 3 r=[9] w=[] x=[]
c : <  channel=0 cmd=ROUTES len=198
c : Adding auto net 2/169.254.0.0/16
c : Adding auto net 2/169.254.169.254/32
c : Adding auto net 2/192.168.1.0/24
c : Adding auto net 2/192.168.1.1/32
c : Adding auto net 2/192.168.1.1/32
c : Adding auto net 2/192.168.1.111/32
c : Adding auto net 2/192.168.1.129/32
c : Adding auto net 2/192.168.1.144/32
c : Adding auto net 2/224.0.0.0/4
c : Adding auto net 2/224.0.0.251/32
c : Adding auto net 2/255.255.255.255/32
firewall manager: Got subnets: [(2, 0, False, '0.0.0.0', 0, 0), (2, 16, False, '169.254.0.0', 0, 0), (2, 32, False, '169.254.169.254', 0, 0), (2, 24, False, '192.168.1.0', 0, 0), (2, 32, False, '192.168.1.1', 0, 0), (2, 32, False, '192.168.1.1', 0, 0), (2, 32, False, '192.168.1.111', 0, 0), (2, 32, False, '192.168.1.129', 0, 0), (2, 32, False, '192.168.1.144', 0, 0), (2, 4, False, '224.0.0.0', 0, 0), (2, 32, False, '224.0.0.251', 0, 0), (2, 32, False, '255.255.255.255', 0, 0)]
firewall manager: Got partial nslist: [(2, '127.0.0.11')]
firewall manager: Got nslist: [(2, '127.0.0.11')]
firewall manager: Got ports: 0,12300,0,12299
firewall manager: Got udp: False, user: None
firewall manager: setting up.
firewall manager: setting up IPv4.
>> iptables -t nat -A sshuttle-12300 -j REDIRECT --dest 169.254.169.254/32 -p tcp --to-ports 12300 -m ttl ! --ttl 63
>> iptables -t nat -A sshuttle-12300 -j REDIRECT --dest 192.168.1.1/32 -p tcp --to-ports 12300 -m ttl ! --ttl 63
>> iptables -t nat -A sshuttle-12300 -j REDIRECT --dest 192.168.1.1/32 -p tcp --to-ports 12300 -m ttl ! --ttl 63
>> iptables -t nat -A sshuttle-12300 -j REDIRECT --dest 192.168.1.111/32 -p tcp --to-ports 12300 -m ttl ! --ttl 63
>> iptables -t nat -A sshuttle-12300 -j REDIRECT --dest 192.168.1.129/32 -p tcp --to-ports 12300 -m ttl ! --ttl 63
>> iptables -t nat -A sshuttle-12300 -j REDIRECT --dest 192.168.1.144/32 -p tcp --to-ports 12300 -m ttl ! --ttl 63
>> iptables -t nat -A sshuttle-12300 -j REDIRECT --dest 224.0.0.251/32 -p tcp --to-ports 12300 -m ttl ! --ttl 63
>> iptables -t nat -A sshuttle-12300 -j REDIRECT --dest 255.255.255.255/32 -p tcp --to-ports 12300 -m ttl ! --ttl 63
>> iptables -t nat -A sshuttle-12300 -j REDIRECT --dest 192.168.1.0/24 -p tcp --to-ports 12300 -m ttl ! --ttl 63
>> iptables -t nat -A sshuttle-12300 -j REDIRECT --dest 169.254.0.0/16 -p tcp --to-ports 12300 -m ttl ! --ttl 63
>> iptables -t nat -A sshuttle-12300 -j REDIRECT --dest 224.0.0.0/4 -p tcp --to-ports 12300 -m ttl ! --ttl 63
>> iptables -t nat -A sshuttle-12300 -j REDIRECT --dest 0.0.0.0/0 -p tcp --to-ports 12300 -m ttl ! --ttl 63
>> iptables -t nat -A sshuttle-12300 -j REDIRECT --dest 127.0.0.11/32 -p udp --dport 53 --to-ports 12299 -m ttl ! --ttl 63
firewall manager: setting up /etc/hosts.
firewall manager: undoing changes.
firewall manager: undoing IPv4 changes.
>> iptables -t nat -D OUTPUT -j sshuttle-12300
>> iptables -t nat -D PREROUTING -j sshuttle-12300
>> iptables -t nat -F sshuttle-12300
>> iptables -t nat -X sshuttle-12300
firewall manager: undoing /etc/hosts changes.
firewall manager: ---> Traceback (most recent call last):
firewall manager: --->   File "/usr/local/lib/python3.8/dist-packages/sshuttle-1.0.5.dev9+g19f653d-py3.8.egg/sshuttle/firewall.py", line 239, in main
firewall manager: --->     rewrite_etc_hosts(hostmap, port_v6 or port_v4)
firewall manager: --->   File "/usr/local/lib/python3.8/dist-packages/sshuttle-1.0.5.dev9+g19f653d-py3.8.egg/sshuttle/firewall.py", line 30, in rewrite_etc_hosts
firewall manager: --->     os.link(HOSTSFILE, BAKFILE)
firewall manager: ---> OSError: [Errno 18] Invalid cross-device link: '/etc/hosts' -> '/etc/hosts.sbak'
firewall manager: ---> 
firewall manager: ---> During handling of the above exception, another exception occurred:
firewall manager: ---> 
firewall manager: ---> Traceback (most recent call last):
firewall manager: --->   File "/usr/local/lib/python3.8/dist-packages/sshuttle-1.0.5.dev9+g19f653d-py3.8.egg/sshuttle/firewall.py", line 279, in main
firewall manager: --->     restore_etc_hosts(port_v6 or port_v4)
firewall manager: --->   File "/usr/local/lib/python3.8/dist-packages/sshuttle-1.0.5.dev9+g19f653d-py3.8.egg/sshuttle/firewall.py", line 51, in restore_etc_hosts
firewall manager: --->     rewrite_etc_hosts({}, port)
firewall manager: --->   File "/usr/local/lib/python3.8/dist-packages/sshuttle-1.0.5.dev9+g19f653d-py3.8.egg/sshuttle/firewall.py", line 30, in rewrite_etc_hosts
firewall manager: --->     os.link(HOSTSFILE, BAKFILE)
firewall manager: ---> OSError: [Errno 18] Invalid cross-device link: '/etc/hosts' -> '/etc/hosts.sbak'

[AtzeDeVries]

i'm also working on this. I did get it to work with adding --net=host to your docker run statement. I don't want this so i'm researching further

[dclong]

I'm encountering the same issue. @AtzeDeVries , may I ask what does --net=host do? It didn't work me.

[skuhl]

If you don’t use the —auto-hosts option, the error after “firewall manager: undoing /etc/hosts changes.” should be fixed by pull request #545.

[nikatlas]

Maybe this helps #759
hosts file is mounted on a docker container