* TcpExtTCPOrigDataSent
This counter is explained by `kernel commit f19c29e3e391`_, I pasted the
-explaination below::
+explanation below::
TCPOrigDataSent: number of outgoing packets with original data (excluding
retransmission but including data-in-SYN). This counter is different from
* TCPSynRetrans
This counter is explained by `kernel commit f19c29e3e391`_, I pasted the
-explaination below::
+explanation below::
TCPSynRetrans: number of SYN and SYN/ACK retransmits to break down
retransmissions into SYN, fast-retransmits, timeout retransmits, etc.
* TCPFastOpenActiveFail
This counter is explained by `kernel commit f19c29e3e391`_, I pasted the
-explaination below::
+explanation below::
TCPFastOpenActiveFail: Fast Open attempts (SYN/data) failed because
the remote does not accept it or the attempts timed out.
Defined in `RFC1213 tcpOutRsts`_. The RFC says this counter indicates
the 'segments sent containing the RST flag', but in linux kernel, this
-couner indicates the segments kerenl tried to send. The sending
+counter indicates the segments kernel tried to send. The sending
process might be failed due to some errors (e.g. memory alloc failed).
.. _RFC1213 tcpOutRsts: https://tools.ietf.org/html/rfc1213#page-52
individually. E.g., if 3 blocks of a SACk is invalid, the
corresponding counter would be updated 3 times. The comment of the
`Add counters for discarded SACK blocks`_ patch has additional
-explaination:
+explanation:
.. _Add counters for discarded SACK blocks: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=18f02545a9a16c9a89778b91a162ad16d510bb32
* TcpExtTCPACKSkippedTimeWait
-Tha ACK is skipped in Time-Wait status, the reason would be either
+The ACK is skipped in Time-Wait status, the reason would be either
PAWS check failed or the received sequence number is out of window.
* TcpExtTCPACKSkippedChallenge
Challenge ACK
=============
-For details of challenge ACK, please refer the explaination of
+For details of challenge ACK, please refer the explanation of
TcpExtTCPACKSkippedChallenge.
* TcpExtTCPChallengeACK
=====
When a socket is under memory pressure, the TCP stack will try to
reclaim memory from the receiving queue and out of order queue. One of
-the reclaiming method is 'collapse', which means allocate a big sbk,
+the reclaiming method is 'collapse', which means allocate a big skb,
copy the contiguous skbs to the single big skb, and free these
contiguous skbs.
IpExtOutOctets 52 0.0
IpExtInNoECTPkts 1 0.0
-Input a string in nc client side again ('world' in our exmaple)::
+Input a string in nc client side again ('world' in our example)::
nstatuser@nstat-a:~$ nc -v nstat-b 9000
Connection to nstat-b 9000 port [tcp/*] succeeded!
TCP window scale option is not used, kernel will try to enable fast
path immediately when the connection comes into the established state,
but if the TCP window scale option is used, kernel will disable the
-fast path at first, and try to enable it after kerenl receives
+fast path at first, and try to enable it after kernel receives
packets. We could use the 'ss' command to verify whether the window
scale option is used. e.g. run below command on either server or
client::
nstatuser@nstat-a:~$ nstat | grep -i abort
TcpExtTCPAbortOnMemory 54 0.0
-Check orphane socket count on client::
+Check orphaned socket count on client::
nstatuser@nstat-a:~$ ss -s
Total: 131 (kernel 0)
nstatuser@nstat-a:~$ for i in {1..3}; do sudo tcpreplay -i ens3 /tmp/syn_fixcsum.pcap; done
-Check snmp cunter on nstat-b::
+Check snmp counter on nstat-b::
nstatuser@nstat-b:~$ nstat | grep -i skip
TcpExtTCPACKSkippedSynRecv 1 0.0
Connection from nstat-a 42132 received!
foo
-On nstat-a, the tcpdump should have caputred the ACK. We should check
+On nstat-a, the tcpdump should have captured the ACK. We should check
the source port numbers of the two nc clients::
nstatuser@nstat-a:~$ ss -ta '( dport = :9000 || dport = :9001 )' | tee
ESTAB 0 0 192.168.122.250:50208 192.168.122.251:9000
ESTAB 0 0 192.168.122.250:42132 192.168.122.251:9001
-Run tcprewrite, change port 9001 to port 9000, chagne port 42132 to
+Run tcprewrite, change port 9001 to port 9000, change port 42132 to
port 50208::
nstatuser@nstat-a:~$ tcprewrite --infile /tmp/seq_pre.pcap --outfile /tmp/seq.pcap -r 9001:9000 -r 42132:50208 --fixcsum