Mar 222008
 


Do you you DHCP to get the IP Address for your Solaris Server or workstation then its worth understanding what your DHCP Agent by default requests for from the DHCP server and help avoid certain network issues like “unknown” hostname issue as I’ve descrbed here.

The DHCP Agent by default requests for the

Subnet Mask

Default Router

Hostname

DNS Domain

Broadcast Address

Encapsulated Vendor Option (vendor specific information as described in RFC 2132)

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Mar 222008
 


If you are using DHCP to receive IP Address for your Sun Solaris system, you may end up with no hostname assigned to the system. This can be confirmed when there is no hostname at the prompt or if the output for the command “hostname” is as follows:

# hostname
unknown

or the /etc/hosts file has an entry as follows:

# cat /etc/hosts
#
# Internet host table
#
127.0.0.1 localhost
192.168.0.3 unknown # Added by DHCP

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Mar 222008
 


In Sun Solaris, UFS file system default maximum file size is 2GB which restricts the maximum size of any file will be restricted to 2GB. This can cause problems with applications like Databases. Solaris 10 by default however sets the Maximum file Size to unlimited on the UFS File System.

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Mar 202008
 


IP Multipathing (IPMP) in Sun Solaris enables the load balancing capabilities and resilience for Network connections with multple Network Interface Cards (NIC).

I discussed here about providing resilience for network connections with multiple NICs on the system. Now, we take it to the next step and make the network connections not only resilient but also load balance the network connections such that both the NICs participating in IPMP are active and forwards traffic. This improves the network throughput and thereby efficiency of the server especially if it is a critical system serving multiple connections.
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Mar 202008
 


In SPARC Servers running Sun Solaris, you can see multiple Network Interface Cards (NICs) or interfaces are all sharing a single MAC-Address than having a unique Factory-default MAC-Address assigned to it. This is because by default, a System-Wide MAC-Address is assigned to all the NICs and hence a ifconfig -a output will show only one MAC-Address.

To confirm this behaviour

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Mar 202008
 


IP Multipathing (IPMP) in Sun Solaris enables the load balancing capabilities and resilience for Network connections with multple Network Interface Cards (NIC).

IPMP is mostly used to provide resilience with network connections wherein a Sun Solaris Server with multiple NICs can be configured such that if the primary NIC fails it automatically failover to the secondary NIC on the system. Also, if it is a multi-switch environment then each Network Interface participating in IPMP can be connection to two different switches such that a network connection failure due to a NIC failure or a switch failure can be avoided.

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Mar 192008
 

The Default Gateway or the Default Router is the IP address (IPv4) to which all the traffic to any target destination(s) which does not have a route in the Routing Table of the server will be forwarded.

This Default Gateway is maintained in the file

/etc/defaultrouter [IPv4 only]

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Mar 192008
 

Solaris Operating Environment by default is configured to both accept and send  the ICMP Redirect messages. According to RFCs, only a router or a gateway device should send an ICMP Redirect message and any other hosts should only be able to receive the ICMP Redirects. If the Solaris server is not acting as a Router or a Gateway then sending ICMP Redirect message should be disabled. The same applies to accepting ICMP Redirect messages if the solaris server is not required to receive ICMP Redirect messages (say a single Router/Gateway network/subnets scenario) as a malicous hacker could send fake ICMP redirect messages to modify the routing table on the host and potentialy cause a Denial of Service attack.

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