3,787 reputation
2718
bio website
location Fort Lauderdale, FL
age 29
visits member for 3 years, 6 months
seen yesterday

System architect & Linux admin for cloud.com (Citrix).


Jun
9
comment Write, wall, who and mesg
What is the difference between wall and a simple loop to do a write to all users one by one? So why block one and not the other?
Jun
9
answered Rewrite URL based off of IP on OpenWRT
Jun
9
comment Iptable Rule to redirect all traffic requesting a specific domain
A better solution would be to work with the DNS requests. Either run a DNS proxy and filter the domain out, or do an iptables text match on the DNS queries and reject those packets.
Jun
9
comment (Serving PHP) Does Apache2 will create new thread on every connection?
Creating threads/processes does not equate to 'resource hungry'. With threads they share memory due to being in the same process. With forks (processes) they still share memory due to linux's copy-on-write memory management. In both models, each worker (for each connection) still has to maintain its own data though. Basically dont jump to conclusions. If this model was bad, it wouldnt exist...
Jun
7
comment Intel server hardware failure; does not work
Why not contact intel? There are likely way too many possible causes for this to be answerable.
Jun
3
comment postfix relay access denied from some IPs
This is likely because you are setting mynetworks and sending from one of those networks when at home or on your phone (which I assume is using your home network). You need to set up user authentication so you can send from any network.
Jun
3
answered Discrepancy between size of database listed in Unix and Mysql
May
27
comment smartcheck Possible Hard Drive Failure Soon
I have seen such issues caused by things other than the drive itself (such as the controller, or other devices on the same bus). Without seeing exactly what the error is, its hard to tell. You can run smartctl -l error /dev/sda to get more info on what those errors were.
May
27
comment CentOS 5/Linux UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY
What does /dev/sda/* have to do with /dev/VolGroup00/LogVol00? Also running fsck on multiple devices which arent necessarily filesystems is a really bad idea, especially if youre going to tack -y on to that command.
May
27
comment How do I delete everything in the /tmp/ folder?
This is insane overkill. You were asked for additional info which you didnt provide, thus nobody was able to explain why you were having issues.
May
24
comment Linux router: ping doesn't route back
@ElBarto I have a sneaking suspicion what it is. Run echo 0 > /proc/sys/net/ipv4/conf/eth1/rp_filter and see if pings work then.
May
24
comment Linux router: ping doesn't route back
NAT is already configured. Notice that the packets in both the tcpdump on the router, and the tcpdump on the remote server both show the packets having been SNATed to the new address. The tcpdumps also show the return packets being properly restored.
May
24
comment Linux router: ping doesn't route back
FORWARD chain has its policy set to ACCEPT, its fine. The tcpdump also shows the packets being properly forwarded (both directions).
May
24
comment Linux router: ping doesn't route back
What about a tcpdump from the 'ubuntu box'? The tcpdump from 'debian router' clearly shows the reply packets being sent. Tcpdump operates outside kernel level filtering, so if the kernel is dropping the replies for any reason, tcpdump on 'ubuntu box' should at least show them making it to the box. On another note, you've provided a lot of useful info in a very clear manner, nice to have here.
May
21
revised Multiple ip to single interface
edited tags
May
21
comment Multiple ip to single interface
@alex88 no, rnxrx really is correct. A /32 netmask will drop traffic because of reverse path filtering. Also you cannot route the traffic back out as with a /32 netmask you cant reach external machines. Also that guide you linked is general purpose, and seems to be written to cover adding IPs in general, not your exact case, and so should be taken as such.
May
21
comment Multiple Linux sysadmins working as root
Can you explain what you mean by "SSH agent forwarding breaks" in the second option? We use this at my work and ssh agent forwarding works just fine.
May
21
comment Multiple Linux sysadmins working as root
Adding multiple users with the same UID adds problems. When applications go to look up the username for a UID number, they can look up the wrong username. Applications which run under root can think theyre running as the wrong user, and lots of weird errors will start popping up (I tried it once).
May
18
comment On a virtual Linux system where storage is on network what's the point of the swap file?
I would say no. When the machine is thrashing the disk, the entire server grinds to a halt. While killing a process isnt good, its worse to have the entire server pretty much useless. And preemptive swapping is a good thing, it swaps out pages that arent being used and can spare the server more memory for cache. Setting swappiness to 0 is rarely (though occasionally) a good practice.
May
18
comment On a virtual Linux system where storage is on network what's the point of the swap file?
This is very inaccurate. Using swap instead of killing processes causes the heaving swapping youre talking about. Preemptively swapping idle pages is what swap is best for as it causes very little thrashing.