Env:
Oracle VM Server 3.3.1
Host: hostbase0
VM: hostvm0
Problem:
User cannot access from outside cluster via ssh.
ssh will hang here:
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[suse@suse ~]$ssh hostvm0 -l root -vvv ... ... debug2: kex_parse_kexinit: reserved 0 debug2: mac_setup: found hmac-md5 debug1: kex: server->client aes128-ctr hmac-md5 none debug2: mac_setup: found hmac-md5 debug1: kex: client->server aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP debug2: dh_gen_key: priv key bits set: 138/256 debug2: bits set: 482/1024 debug1: SSH2_MSG_KEX_DH_GEX_INIT sent debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY <-- stops here ^C |
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#ssh host06 -vvv ... ... debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: mac_setup: found hmac-md5 debug1: kex: server->client aes128-ctr hmac-md5 none debug2: mac_setup: found hmac-md5 debug1: kex: client->server aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP <--stops here. debug3: Wrote 24 bytes for a total of 1005 |
from ifconfig output, I can see a lot of err/invalid packages:
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RX packets:1321 errors:21 dropped:1073 overruns:0 frame:0 |
from sys log: can see a lot of err mesg on xen_netfront.
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Nov 5 21:32:18 hostvm0 kernel: xen_netfront: GSO size must not be zero Nov 5 21:32:20 hostvm0 kernel: xen_netfront: GSO size must not be zero Nov 5 21:32:51 hostvm0 kernel: xen_netfront: GSO size must not be zero Nov 5 21:32:57 hostvm0 kernel: xen_netfront: GSO size must not be zero Nov 5 21:32:57 hostvm0 kernel: xen_netfront: GSO size must not be zero |
Fix:
It’s an oracle bug which marked in Metalink ID:1929676.1
Upgrade Linux kernel on Host to latest:
current kernel: kernel-uek-3.8.13-26.4.2.el6uek.x86_64
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# yum update -y kernel-uek ... ... Installing : kernel-uek-firmware-3.8.13-44.1.4.el6uek.noarch 1/2 Installing : kernel-uek-3.8.13-44.1.4.el6uek.x86_64 2/2 |