Networking [SOLVED]: IPV6 ssh stops working 10 minutes after startup

Networking [SOLVED]: IPV6 ssh stops working 10 minutes after startup

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  • #35835

    Anonymous

    QuestionQuestion

    I have a Ubuntu Linux 16.04.1 server. 10 minutes after startup SSH over IPV6 stops working and I can no longer connect to SSH using my IPV6 address. IPV4 works fine all the time.

    Would anyone have any suggestions? I am banging my head off the desk nearly.. Happy to provide any logs if needed…

    If I reboot the server, IPV6 works fine again for 10 minutes.

    Output of /etc/ssh/sshd_config:

        # Package generated configuration file
    # See the sshd_config(5) manpage for details
    
    # What ports, IPs and protocols we listen for
    Port 7000
    # Use these options to restrict which interfaces/protocols sshd will bind to
    #ListenAddress ::
    #ListenAddress 0.0.0.0
    Protocol 2
    # HostKeys for protocol version 2
    HostKey /etc/ssh/ssh_host_rsa_key
    HostKey /etc/ssh/ssh_host_dsa_key
    HostKey /etc/ssh/ssh_host_ecdsa_key
    HostKey /etc/ssh/ssh_host_ed25519_key
    #Privilege Separation is turned on for security
    UsePrivilegeSeparation yes
    
    # Lifetime and size of ephemeral version 1 server key
    KeyRegenerationInterval 3600
    ServerKeyBits 1024
    
    # Logging
    SyslogFacility AUTH
    LogLevel INFO
    
    # Authentication:
    LoginGraceTime 120
    PermitRootLogin yes
    StrictModes yes
    
    RSAAuthentication yes
    PubkeyAuthentication yes
    #AuthorizedKeysFile %h/.ssh/authorized_keys
    
    # Don't read the user's ~/.rhosts and ~/.shosts files
    IgnoreRhosts yes
    # For this to work you will also need host keys in /etc/ssh_known_hosts
    RhostsRSAAuthentication no
    # similar for protocol version 2
    HostbasedAuthentication no
    # Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication
    #IgnoreUserKnownHosts yes
    
    # To enable empty passwords, change to yes (NOT RECOMMENDED)
    PermitEmptyPasswords no
    
    # Change to yes to enable challenge-response passwords (beware issues with
    # some PAM modules and threads)
    ChallengeResponseAuthentication no
    
    # Change to no to disable tunnelled clear text passwords
    #PasswordAuthentication yes
    
    # Kerberos options
    #KerberosAuthentication no
    #KerberosGetAFSToken no
    #KerberosOrLocalPasswd yes
    #KerberosTicketCleanup yes
    
    # GSSAPI options
    #GSSAPIAuthentication no
    #GSSAPICleanupCredentials yes
    
    X11Forwarding yes
    X11DisplayOffset 10
    PrintMotd no
    PrintLastLog yes
    TCPKeepAlive yes
    #UseLogin no
    
    #MaxStartups 10:30:60
    #Banner /etc/issue.net
    
    # Allow client to pass locale environment variables
    AcceptEnv LANG LC_*
    
    Subsystem sftp /usr/lib/openssh/sftp-server
    
    # Set this to 'yes' to enable PAM authentication, account processing,
    # and session processing. If this is enabled, PAM authentication will
    # be allowed through the ChallengeResponseAuthentication and
    # PasswordAuthentication.  Depending on your PAM configuration,
    # PAM authentication via ChallengeResponseAuthentication may bypass
    # the setting of "PermitRootLogin without-password".
    # If you just want the PAM account and session checks to run without
    # PAM authentication, then enable this but set PasswordAuthentication
    # and ChallengeResponseAuthentication to 'no'.
    UsePAM yes
    

    Output of ip6tables -L -v -n

    Chain INPUT (policy DROP 0 packets, 0 bytes)
     pkts bytes target     prot opt in     out     source               destination         
     1209  138K LOCALINPUT  all      !lo    *       ::/0                 ::/0                
        3   147 ACCEPT     all      lo     *       ::/0                 ::/0                
        0     0 INVALID    tcp      !lo    *       ::/0                 ::/0                
        6   576 ACCEPT     all      !lo    *       ::/0                 ::/0                 state RELATED,ESTABLISHED
        0     0 ACCEPT     tcp      !lo    *       ::/0                 ::/0                 state NEW tcp dpt:25
        0     0 ACCEPT     tcp      !lo    *       ::/0                 ::/0                 state NEW tcp dpt:7000
        0     0 ACCEPT     tcp      !lo    *       ::/0                 ::/0                 state NEW tcp dpt:8080
        0     0 ACCEPT     udp      !lo    *       ::/0                 ::/0                 state NEW udp dpt:25
        0     0 ACCEPT     udp      !lo    *       ::/0                 ::/0                 state NEW udp dpt:7000
        0     0 ACCEPT     udp      !lo    *       ::/0                 ::/0                 state NEW udp dpt:8080
        4   280 ACCEPT     icmpv6    !lo    *       ::/0                 ::/0                
        0     0 LOGDROPIN  all      !lo    *       ::/0                 ::/0                
    
    Chain FORWARD (policy DROP 0 packets, 0 bytes)
     pkts bytes target     prot opt in     out     source               destination         
    
    Chain OUTPUT (policy DROP 0 packets, 0 bytes)
     pkts bytes target     prot opt in     out     source               destination         
      888  132K LOCALOUTPUT  all      *      !lo     ::/0                 ::/0                
        0     0 ACCEPT     tcp      *      !lo     ::/0                 ::/0                 tcp dpt:53
        0     0 ACCEPT     udp      *      !lo     ::/0                 ::/0                 udp dpt:53
        0     0 ACCEPT     tcp      *      !lo     ::/0                 ::/0                 tcp spt:53
        0     0 ACCEPT     udp      *      !lo     ::/0                 ::/0                 udp spt:53
        3   147 ACCEPT     all      *      lo      ::/0                 ::/0                
        0     0 INVALID    tcp      *      !lo     ::/0                 ::/0                
        0     0 ACCEPT     all      *      !lo     ::/0                 ::/0                 state RELATED,ESTABLISHED
        0     0 ACCEPT     tcp      *      !lo     ::/0                 ::/0                 state NEW tcp dpts:1:65535
        6   576 ACCEPT     udp      *      !lo     ::/0                 ::/0                 state NEW udp dpts:1:65535
        4   264 ACCEPT     icmpv6    *      !lo     ::/0                 ::/0                
        0     0 LOGDROPOUT  all      *      !lo     ::/0                 ::/0                
    
    Chain ALLOWIN (1 references)
     pkts bytes target     prot opt in     out     source               destination         
        0     0 ACCEPT     all      !lo    *       X  ::/0                
        0     0 ACCEPT     all      !lo    *       X  ::/0                
        0     0 ACCEPT     all      !lo    *       X  ::/0                
        0     0 ACCEPT     all      !lo    *       X  ::/0                
        0     0 ACCEPT     all      !lo    *       X  ::/0                
        0     0 ACCEPT     all      !lo    *       X  ::/0                
        0     0 ACCEPT     all      !lo    *       X  ::/0                
        0     0 ACCEPT     all      !lo    *       X  ::/0                
        0     0 ACCEPT     all      !lo    *       X  ::/0                
     1199  137K ACCEPT     all      !lo    *       X  ::/0                
    
    Chain ALLOWOUT (1 references)
     pkts bytes target     prot opt in     out     source               destination         
        0     0 ACCEPT     all      *      !lo     ::/0                 X 
        0     0 ACCEPT     all      *      !lo     ::/0                 X 
        0     0 ACCEPT     all      *      !lo     ::/0                 X 
        0     0 ACCEPT     all      *      !lo     ::/0                 X 
        0     0 ACCEPT     all      *      !lo     ::/0                 X 
        0     0 ACCEPT     all      *      !lo     ::/0                 X 
        0     0 ACCEPT     all      *      !lo     ::/0                 X 
        0     0 ACCEPT     all      *      !lo     ::/0                 X 
        0     0 ACCEPT     all      *      !lo     ::/0                 X 
      878  131K ACCEPT     all      *      !lo     ::/0                 X 
    
    Chain DENYIN (1 references)
     pkts bytes target     prot opt in     out     source               destination         
    
    Chain DENYOUT (1 references)
     pkts bytes target     prot opt in     out     source               destination         
    
    Chain INVALID (2 references)
     pkts bytes target     prot opt in     out     source               destination         
        0     0 INVDROP    all      *      *       ::/0                 ::/0                 state INVALID
        0     0 INVDROP    tcp      *      *       ::/0                 ::/0                 tcp flags:0x3F/0x00
        0     0 INVDROP    tcp      *      *       ::/0                 ::/0                 tcp flags:0x3F/0x3F
        0     0 INVDROP    tcp      *      *       ::/0                 ::/0                 tcp flags:0x03/0x03
        0     0 INVDROP    tcp      *      *       ::/0                 ::/0                 tcp flags:0x06/0x06
        0     0 INVDROP    tcp      *      *       ::/0                 ::/0                 tcp flags:0x05/0x05
        0     0 INVDROP    tcp      *      *       ::/0                 ::/0                 tcp flags:0x11/0x01
        0     0 INVDROP    tcp      *      *       ::/0                 ::/0                 tcp flags:0x18/0x08
        0     0 INVDROP    tcp      *      *       ::/0                 ::/0                 tcp flags:0x30/0x20
        0     0 INVDROP    tcp      *      *       ::/0                 ::/0                 tcp flags:!0x17/0x02 state NEW
    
    Chain INVDROP (10 references)
     pkts bytes target     prot opt in     out     source               destination         
        0     0 DROP       all      *      *       ::/0                 ::/0                
    
    Chain LOCALINPUT (1 references)
     pkts bytes target     prot opt in     out     source               destination         
     1209  138K ALLOWIN    all      !lo    *       ::/0                 ::/0                
       10   856 DENYIN     all      !lo    *       ::/0                 ::/0                
    
    Chain LOCALOUTPUT (1 references)
     pkts bytes target     prot opt in     out     source               destination         
      888  132K ALLOWOUT   all      *      !lo     ::/0                 ::/0                
       10   840 DENYOUT    all      *      !lo     ::/0                 ::/0                
    
    Chain LOGDROPIN (1 references)
     pkts bytes target     prot opt in     out     source               destination         
        0     0 DROP       tcp      *      *       ::/0                 ::/0                 tcp dpt:67
        0     0 DROP       udp      *      *       ::/0                 ::/0                 udp dpt:67
        0     0 DROP       tcp      *      *       ::/0                 ::/0                 tcp dpt:68
        0     0 DROP       udp      *      *       ::/0                 ::/0                 udp dpt:68
        0     0 DROP       tcp      *      *       ::/0                 ::/0                 tcp dpt:111
        0     0 DROP       udp      *      *       ::/0                 ::/0                 udp dpt:111
        0     0 DROP       tcp      *      *       ::/0                 ::/0                 tcp dpt:113
        0     0 DROP       udp      *      *       ::/0                 ::/0                 udp dpt:113
        0     0 DROP       tcp      *      *       ::/0                 ::/0                 tcp dpts:135:139
        0     0 DROP       udp      *      *       ::/0                 ::/0                 udp dpts:135:139
        0     0 DROP       tcp      *      *       ::/0                 ::/0                 tcp dpt:445
        0     0 DROP       udp      *      *       ::/0                 ::/0                 udp dpt:445
        0     0 DROP       tcp      *      *       ::/0                 ::/0                 tcp dpt:500
        0     0 DROP       udp      *      *       ::/0                 ::/0                 udp dpt:500
        0     0 DROP       tcp      *      *       ::/0                 ::/0                 tcp dpt:513
        0     0 DROP       udp      *      *       ::/0                 ::/0                 udp dpt:513
        0     0 DROP       tcp      *      *       ::/0                 ::/0                 tcp dpt:520
        0     0 DROP       udp      *      *       ::/0                 ::/0                 udp dpt:520
        0     0 LOG        tcp      *      *       ::/0                 ::/0                 limit: avg 30/min burst 5 LOG flags 0 level 4 prefix "Firewall: *TCP6IN Blocked* "
        0     0 LOG        udp      *      *       ::/0                 ::/0                 limit: avg 30/min burst 5 LOG flags 0 level 4 prefix "Firewall: *UDP6IN Blocked* "
        0     0 LOG        icmpv6    *      *       ::/0                 ::/0                 limit: avg 30/min burst 5 LOG flags 0 level 4 prefix "Firewall: *ICMP6IN Blocked* "
        0     0 DROP       all      *      *       ::/0                 ::/0                
    
    Chain LOGDROPOUT (1 references)
     pkts bytes target     prot opt in     out     source               destination         
        0     0 LOG        tcp      *      *       ::/0                 ::/0                 tcp flags:0x17/0x02 limit: avg 30/min burst 5 LOG flags 8 level 4 prefix "Firewall: *TCP6OUT Blocked* "
        0     0 LOG        udp      *      *       ::/0                 ::/0                 limit: avg 30/min burst 5 LOG flags 8 level 4 prefix "Firewall: *UDP6OUT Blocked* "
        0     0 LOG        icmpv6    *      *       ::/0                 ::/0                 limit: avg 30/min burst 5 LOG flags 8 level 4 prefix "Firewall: *ICMP6OUT Blocked* "
        0     0 REJECT     all      *      *       ::/0                 ::/0                 reject-with icmp6-port-unreachable
    

    #35836

    Anonymous

    Accepted AnswerAnswer

    Turns out it was an issue with a router at my providers end. Apparently it was kicking the subnet off.. All working now! woo..

    Thanks for the help!

    Source: https://serverfault.com/questions/886687/ipv6-ssh-stops-working-10-minutes-after-startup
    Author: Dara G
    Creative Commons License
    This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

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